vtgl

stb_truetype.h (149826B)

---

 // stb_truetype.h - v1.26 - public domain
 // authored from 2009-2021 by Sean Barrett / RAD Game Tools
 //
 // =======================================================================
 //
 //    NO SECURITY GUARANTEE -- DO NOT USE THIS ON UNTRUSTED FONT FILES
 //
 // This library does no range checking of the offsets found in the file,
 // meaning an attacker can use it to read arbitrary memory.
 //
 // =======================================================================
 //
 //   This library processes TrueType files:
 //        parse files
 //        extract glyph metrics
 //        extract glyph shapes
 //        render glyphs to one-channel bitmaps with antialiasing (box filter)
 //        render glyphs to one-channel SDF bitmaps (signed-distance field/function)
 //
 //   Todo:
 //        non-MS cmaps
 //        crashproof on bad data
 //        hinting? (no longer patented)
 //        cleartype-style AA?
 //        optimize: use simple memory allocator for intermediates
 //        optimize: build edge-list directly from curves
 //        optimize: rasterize directly from curves?
 //
 // ADDITIONAL CONTRIBUTORS
 //
 //   Mikko Mononen: compound shape support, more cmap formats
 //   Tor Andersson: kerning, subpixel rendering
 //   Dougall Johnson: OpenType / Type 2 font handling
 //   Daniel Ribeiro Maciel: basic GPOS-based kerning
 //
 //   Misc other:
 //       Ryan Gordon
 //       Simon Glass
 //       github:IntellectualKitty
 //       Imanol Celaya
 //       Daniel Ribeiro Maciel
 //
 //   Bug/warning reports/fixes:
 //       "Zer" on mollyrocket       Fabian "ryg" Giesen   github:NiLuJe
 //       Cass Everitt               Martins Mozeiko       github:aloucks
 //       stoiko (Haemimont Games)   Cap Petschulat        github:oyvindjam
 //       Brian Hook                 Omar Cornut           github:vassvik
 //       Walter van Niftrik         Ryan Griege
 //       David Gow                  Peter LaValle
 //       David Given                Sergey Popov
 //       Ivan-Assen Ivanov          Giumo X. Clanjor
 //       Anthony Pesch              Higor Euripedes
 //       Johan Duparc               Thomas Fields
 //       Hou Qiming                 Derek Vinyard
 //       Rob Loach                  Cort Stratton
 //       Kenney Phillis Jr.         Brian Costabile
 //       Ken Voskuil (kaesve)       Yakov Galka
 //
 // VERSION HISTORY
 //
 //   1.26 (2021-08-28) fix broken rasterizer
 //   1.25 (2021-07-11) many fixes
 //   1.24 (2020-02-05) fix warning
 //   1.23 (2020-02-02) query SVG data for glyphs; query whole kerning table (but only kern not GPOS)
 //   1.22 (2019-08-11) minimize missing-glyph duplication; fix kerning if both 'GPOS' and 'kern' are defined
 //   1.21 (2019-02-25) fix warning
 //   1.20 (2019-02-07) PackFontRange skips missing codepoints; GetScaleFontVMetrics()
 //   1.19 (2018-02-11) GPOS kerning, STBTT_fmod
 //   1.18 (2018-01-29) add missing function
 //   1.17 (2017-07-23) make more arguments const; doc fix
 //   1.16 (2017-07-12) SDF support
 //   1.15 (2017-03-03) make more arguments const
 //   1.14 (2017-01-16) num-fonts-in-TTC function
 //   1.13 (2017-01-02) support OpenType fonts, certain Apple fonts
 //   1.12 (2016-10-25) suppress warnings about casting away const with -Wcast-qual
 //   1.11 (2016-04-02) fix unused-variable warning
 //   1.10 (2016-04-02) user-defined fabs(); rare memory leak; remove duplicate typedef
 //   1.09 (2016-01-16) warning fix; avoid crash on outofmem; use allocation userdata properly
 //   1.08 (2015-09-13) document stbtt_Rasterize(); fixes for vertical & horizontal edges
 //   1.07 (2015-08-01) allow PackFontRanges to accept arrays of sparse codepoints;
 //                     variant PackFontRanges to pack and render in separate phases;
 //                     fix stbtt_GetFontOFfsetForIndex (never worked for non-0 input?);
 //                     fixed an assert() bug in the new rasterizer
 //                     replace assert() with STBTT_assert() in new rasterizer
 //
 //   Full history can be found at the end of this file.
 //
 // LICENSE
 //
 //   See end of file for license information.
 //
 // USAGE
 //
 //   Include this file in whatever places need to refer to it. In ONE C/C++
 //   file, write:
 //      #define STB_TRUETYPE_IMPLEMENTATION
 //   before the #include of this file. This expands out the actual
 //   implementation into that C/C++ file.
 //
 //   To make the implementation private to the file that generates the implementation,
 //      #define STBTT_STATIC
 //
 //   "Load" a font file from a memory buffer (you have to keep the buffer loaded)
 //           stbtt_InitFont()
 //           stbtt_GetFontOffsetForIndex()        -- indexing for TTC font collections
 //           stbtt_GetNumberOfFonts()             -- number of fonts for TTC font collections
 //
 //   Render a unicode codepoint to a bitmap
 //           stbtt_MakeGlyphBitmap()              -- renders into bitmap you provide
 //           stbtt_GetGlyphBitmapBox()            -- how big the bitmap must be
 //
 //   Character advance/positioning
 //           stbtt_GetGlyphHMetrics()
 //           stbtt_GetFontVMetrics()
 //           stbtt_GetFontVMetricsOS2()
 //           stbtt_GetGlyphKernAdvance()
 //
 //   Starting with version 1.06, the rasterizer was replaced with a new,
 //   faster and generally-more-precise rasterizer. The new rasterizer more
 //   accurately measures pixel coverage for anti-aliasing, except in the case
 //   where multiple shapes overlap, in which case it overestimates the AA pixel
 //   coverage. Thus, anti-aliasing of intersecting shapes may look wrong. If
 //   this turns out to be a problem, you can re-enable the old rasterizer with
 //        #define STBTT_RASTERIZER_VERSION 1 (removed)
 //   which will incur about a 15% speed hit.
 //
 // ADDITIONAL DOCUMENTATION
 //
 //   Immediately after this block comment are a series of sample programs.
 //
 //   After the sample programs is the "header file" section. This section
 //   includes documentation for each API function.
 //
 //   Some important concepts to understand to use this library:
 //
 //      Codepoint
 //         Characters are defined by unicode codepoints, e.g. 65 is
 //         uppercase A, 231 is lowercase c with a cedilla, 0x7e30 is
 //         the hiragana for "ma".
 //
 //      Glyph
 //         A visual character shape (every codepoint is rendered as
 //         some glyph)
 //
 //      Glyph index
 //         A font-specific integer ID representing a glyph
 //
 //      Baseline
 //         Glyph shapes are defined relative to a baseline, which is the
 //         bottom of uppercase characters. Characters extend both above
 //         and below the baseline.
 //
 //      Current Point
 //         As you draw text to the screen, you keep track of a "current point"
 //         which is the origin of each character. The current point's vertical
 //         position is the baseline. Even "baked fonts" use this model.
 //
 //      Vertical Font Metrics
 //         The vertical qualities of the font, used to vertically position
 //         and space the characters. See docs for stbtt_GetFontVMetrics.
 //
 //      Font Size in Pixels or Points
 //         The preferred interface for specifying font sizes in stb_truetype
 //         is to specify how tall the font's vertical extent should be in pixels.
 //         If that sounds good enough, skip the next paragraph.
 //
 //         Most font APIs instead use "points", which are a common typographic
 //         measurement for describing font size, defined as 72 points per inch.
 //         stb_truetype provides a point API for compatibility. However, true
 //         "per inch" conventions don't make much sense on computer displays
 //         since different monitors have different number of pixels per
 //         inch. For example, Windows traditionally uses a convention that
 //         there are 96 pixels per inch, thus making 'inch' measurements have
 //         nothing to do with inches, and thus effectively defining a point to
 //         be 1.333 pixels. Additionally, the TrueType font data provides
 //         an explicit scale factor to scale a given font's glyphs to points,
 //         but the author has observed that this scale factor is often wrong
 //         for non-commercial fonts, thus making fonts scaled in points
 //         according to the TrueType spec incoherently sized in practice.
 //
 // DETAILED USAGE:
 //
 //  Scale:
 //    Select how high you want the font to be, in points or pixels.
 //    Call ScaleForPixelHeight or ScaleForMappingEmToPixels to compute
 //    a scale factor SF that will be used by all other functions.
 //
 //  Baseline:
 //    You need to select a y-coordinate that is the baseline of where
 //    your text will appear. Call GetFontBoundingBox to get the baseline-relative
 //    bounding box for all characters. SF*-y0 will be the distance in pixels
 //    that the worst-case character could extend above the baseline, so if
 //    you want the top edge of characters to appear at the top of the
 //    screen where y=0, then you would set the baseline to SF*-y0.
 //
 //  Current point:
 //    Set the current point where the first character will appear. The
 //    first character could extend left of the current point; this is font
 //    dependent. You can either choose a current point that is the leftmost
 //    point and hope, or add some padding, or check the bounding box or
 //    left-side-bearing of the first character to be displayed and set
 //    the current point based on that.
 //
 //  Displaying a character:
 //    Compute the bounding box of the character. It will contain signed values
 //    relative to <current_point, baseline>. I.e. if it returns x0,y0,x1,y1,
 //    then the character should be displayed in the rectangle from
 //    <current_point+SF*x0, baseline+SF*y0> to <current_point+SF*x1,baseline+SF*y1).
 //
 //  Advancing for the next character:
 //    Call GlyphHMetrics, and compute 'current_point += SF * advance'.
 //
 //
 // ADVANCED USAGE
 //
 //   Quality:
 //
 //    - Use the functions with Subpixel at the end to allow your characters
 //      to have subpixel positioning. Since the font is anti-aliased, not
 //      hinted, this is very import for quality. (This is not possible with
 //      baked fonts.)
 //
 //    - Kerning is now supported, and if you're supporting subpixel rendering
 //      then kerning is worth using to give your text a polished look.
 //
 //   Performance:
 //
 //    - Convert Unicode codepoints to glyph indexes and operate on the glyphs;
 //      if you don't do this, stb_truetype is forced to do the conversion on
 //      every call.
 //
 //    - There are a lot of memory allocations. We should modify it to take
 //      a temp buffer and allocate from the temp buffer (without freeing),
 //      should help performance a lot.
 //
 // NOTES
 //
 //   The system uses the raw data found in the .ttf file without changing it
 //   and without building auxiliary data structures. This is a bit inefficient
 //   on little-endian systems (the data is big-endian), but assuming you're
 //   caching the bitmaps or glyph shapes this shouldn't be a big deal.
 //
 //   It appears to be very hard to programmatically determine what font a
 //   given file is in a general way. I provide an API for this, but I don't
 //   recommend it.
 //
 //
 // PERFORMANCE MEASUREMENTS FOR 1.06:
 //
 //                      32-bit     64-bit
 //   Previous release:  8.83 s     7.68 s
 //   Pool allocations:  7.72 s     6.34 s
 //   Inline sort     :  6.54 s     5.65 s
 //   New rasterizer  :  5.63 s     5.00 s
 
 //////////////////////////////////////////////////////////////////////////////
 //////////////////////////////////////////////////////////////////////////////
 ////
 ////   INTEGRATION WITH YOUR CODEBASE
 ////
 ////   The following sections allow you to supply alternate definitions
 ////   of C library functions used by stb_truetype, e.g. if you don't
 ////   link with the C runtime library.
 
 #ifdef STB_TRUETYPE_IMPLEMENTATION
    typedef u8  stbtt_uint8;
    typedef i8  stbtt_int8;
    typedef u16 stbtt_uint16;
    typedef i16 stbtt_int16;
    typedef u32 stbtt_uint32;
    typedef i32 stbtt_int32;
 
    // e.g. #define your own STBTT_ifloor/STBTT_iceil() to avoid math.h
    #ifndef STBTT_ifloor
    #include <math.h>
    #define STBTT_ifloor(x)   ((int) floor(x))
    #define STBTT_iceil(x)    ((int) ceil(x))
    #endif
 
    #ifndef STBTT_sqrt
    #include <math.h>
    #define STBTT_sqrt(x)      sqrt(x)
    #define STBTT_pow(x,y)     pow(x,y)
    #endif
 
    #ifndef STBTT_fmod
    #include <math.h>
    #define STBTT_fmod(x,y)    fmod(x,y)
    #endif
 
    #ifndef STBTT_cos
    #include <math.h>
    #define STBTT_cos(x)       cos(x)
    #define STBTT_acos(x)      acos(x)
    #endif
 
    #define STBTT_fabs(x)      ABS(x)
    #define STBTT_assert(x)    ASSERT(x)
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
 ////
 ////   INTERFACE
 ////
 ////
 
 #ifndef __STB_INCLUDE_STB_TRUETYPE_H__
 #define __STB_INCLUDE_STB_TRUETYPE_H__
 
 #ifdef STBTT_STATIC
 #define STBTT_DEF static
 #else
 #define STBTT_DEF extern
 #endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 // private structure
 typedef struct
 {
    unsigned char *data;
    int cursor;
    int size;
 } stbtt__buf;
 
 
 STBTT_DEF void stbtt_GetScaledFontVMetrics(unsigned char *fontdata, int index, float size, float *ascent, float *descent, float *lineGap);
 // Query the font vertical metrics without having to create a font first.
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // FONT LOADING
 //
 //
 
 STBTT_DEF int stbtt_GetNumberOfFonts(unsigned char *data);
 // This function will determine the number of fonts in a font file.  TrueType
 // collection (.ttc) files may contain multiple fonts, while TrueType font
 // (.ttf) files only contain one font. The number of fonts can be used for
 // indexing with the previous function where the index is between zero and one
 // less than the total fonts. If an error occurs, -1 is returned.
 
 STBTT_DEF int stbtt_GetFontOffsetForIndex(unsigned char *data, int index);
 // Each .ttf/.ttc file may have more than one font. Each font has a sequential
 // index number starting from 0. Call this function to get the font offset for
 // a given index; it returns -1 if the index is out of range. A regular .ttf
 // file will only define one font and it always be at offset 0, so it will
 // return '0' for index 0, and -1 for all other indices.
 
 // The following structure is defined publicly so you can declare one on
 // the stack or as a global or etc, but you should treat it as opaque.
 typedef struct stbtt_fontinfo {
    unsigned char  * data;              // pointer to .ttf file
    int              fontstart;         // offset of start of font
 
    int numGlyphs;                     // number of glyphs, needed for range checking
 
    int loca,head,glyf,hhea,hmtx,kern,gpos,svg; // table locations as offset from start of .ttf
    int index_map;                     // a cmap mapping for our chosen character encoding
    int indexToLocFormat;              // format needed to map from glyph index to glyph
 
    stbtt__buf cff;                    // cff font data
    stbtt__buf charstrings;            // the charstring index
    stbtt__buf gsubrs;                 // global charstring subroutines index
    stbtt__buf subrs;                  // private charstring subroutines index
    stbtt__buf fontdicts;              // array of font dicts
    stbtt__buf fdselect;               // map from glyph to fontdict
 } stbtt_fontinfo;
 
 STBTT_DEF int stbtt_InitFont(stbtt_fontinfo *info, unsigned char *data, int offset);
 // Given an offset into the file that defines a font, this function builds
 // the necessary cached info for the rest of the system. You must allocate
 // the stbtt_fontinfo yourself, and stbtt_InitFont will fill it out. You don't
 // need to do anything special to free it, because the contents are pure
 // value data with no additional data structures. Returns 0 on failure.
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // CHARACTER TO GLYPH-INDEX CONVERSIOn
 
 STBTT_DEF int stbtt_FindGlyphIndex(const stbtt_fontinfo *info, int unicode_codepoint);
 // If you're going to perform multiple operations on the same character
 // and you want a speed-up, call this function with the character you're
 // going to process, then use glyph-based functions instead of the
 // codepoint-based functions.
 // Returns 0 if the character codepoint is not defined in the font.
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // CHARACTER PROPERTIES
 //
 
 STBTT_DEF float stbtt_ScaleForPixelHeight(const stbtt_fontinfo *info, float pixels);
 // computes a scale factor to produce a font whose "height" is 'pixels' tall.
 // Height is measured as the distance from the highest ascender to the lowest
 // descender; in other words, it's equivalent to calling stbtt_GetFontVMetrics
 // and computing:
 //       scale = pixels / (ascent - descent)
 // so if you prefer to measure height by the ascent only, use a similar calculation.
 
 STBTT_DEF float stbtt_ScaleForMappingEmToPixels(const stbtt_fontinfo *info, float pixels);
 // computes a scale factor to produce a font whose EM size is mapped to
 // 'pixels' tall. This is probably what traditional APIs compute, but
 // I'm not positive.
 
 STBTT_DEF void stbtt_GetFontVMetrics(const stbtt_fontinfo *info, int *ascent, int *descent, int *lineGap);
 // ascent is the coordinate above the baseline the font extends; descent
 // is the coordinate below the baseline the font extends (i.e. it is typically negative)
 // lineGap is the spacing between one row's descent and the next row's ascent...
 // so you should advance the vertical position by "*ascent - *descent + *lineGap"
 //   these are expressed in unscaled coordinates, so you must multiply by
 //   the scale factor for a given size
 
 STBTT_DEF int  stbtt_GetFontVMetricsOS2(const stbtt_fontinfo *info, int *typoAscent, int *typoDescent, int *typoLineGap);
 // analogous to GetFontVMetrics, but returns the "typographic" values from the OS/2
 // table (specific to MS/Windows TTF files).
 //
 // Returns 1 on success (table present), 0 on failure.
 
 STBTT_DEF void stbtt_GetFontBoundingBox(const stbtt_fontinfo *info, int *x0, int *y0, int *x1, int *y1);
 // the bounding box around all possible characters
 
 STBTT_DEF void stbtt_GetGlyphHMetrics(const stbtt_fontinfo *info, int glyph_index, int *advanceWidth, int *leftSideBearing);
 // leftSideBearing is the offset from the current horizontal position to the left edge of the character
 // advanceWidth is the offset from the current horizontal position to the next horizontal position
 //   these are expressed in unscaled coordinates
 
 STBTT_DEF int  stbtt_GetGlyphKernAdvance(const stbtt_fontinfo *info, int glyph1, int glyph2);
 // an additional amount to add to the 'advance' value between ch1 and ch2
 
 STBTT_DEF int  stbtt_GetGlyphBox(const stbtt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1);
 // Gets the bounding box of the visible part of the glyph, in unscaled coordinates
 
 typedef struct stbtt_kerningentry
 {
    int glyph1; // use stbtt_FindGlyphIndex
    int glyph2;
    int advance;
 } stbtt_kerningentry;
 
 STBTT_DEF int  stbtt_GetKerningTableLength(const stbtt_fontinfo *info);
 STBTT_DEF int  stbtt_GetKerningTable(const stbtt_fontinfo *info, stbtt_kerningentry* table, int table_length);
 // Retrieves a complete list of all of the kerning pairs provided by the font
 // stbtt_GetKerningTable never writes more than table_length entries and returns how many entries it did write.
 // The table will be sorted by (a.glyph1 == b.glyph1)?(a.glyph2 < b.glyph2):(a.glyph1 < b.glyph1)
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // GLYPH SHAPES (you probably don't need these, but they have to go before
 // the bitmaps for C declaration-order reasons)
 //
 
 #ifndef STBTT_vmove // you can predefine these to use different values (but why?)
    enum {
       STBTT_vmove=1,
       STBTT_vline,
       STBTT_vcurve,
       STBTT_vcubic
    };
 #endif
 
 #ifndef stbtt_vertex // you can predefine this to use different values
                    // (we share this with other code at RAD)
    #define stbtt_vertex_type short // can't use stbtt_int16 because that's not visible in the header file
    typedef struct
    {
       stbtt_vertex_type x,y,cx,cy,cx1,cy1;
       unsigned char type,padding;
    } stbtt_vertex;
 #endif
 
 STBTT_DEF int stbtt_IsGlyphEmpty(const stbtt_fontinfo *info, int glyph_index);
 // returns non-zero if nothing is drawn for this glyph
 
 STBTT_DEF int stbtt_GetGlyphShape(Arena *a, const stbtt_fontinfo *info, int glyph_index,
                                   stbtt_vertex **vertices);
 // returns # of vertices and fills *vertices with the pointer to them
 //   these are expressed in "unscaled" coordinates
 //
 // The shape is a series of contours. Each one starts with
 // a STBTT_moveto, then consists of a series of mixed
 // STBTT_lineto and STBTT_curveto segments. A lineto
 // draws a line from previous endpoint to its x,y; a curveto
 // draws a quadratic bezier from previous endpoint to
 // its x,y, using cx,cy as the bezier control point.
 
 STBTT_DEF unsigned char *stbtt_FindSVGDoc(const stbtt_fontinfo *info, int gl);
 STBTT_DEF int stbtt_GetGlyphSVG(const stbtt_fontinfo *info, int gl, const char **svg);
 // fills svg with the character's SVG data.
 // returns data size or 0 if SVG not found.
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // BITMAP RENDERING
 //
 
 STBTT_DEF void stbtt_MakeGlyphBitmap(Arena a, const stbtt_fontinfo *info, unsigned char *output, int out_w,
                                      int out_h, int out_stride, float scale_x, float scale_y, int glyph);
 // renders a single-channel 8bpp bitmap glyph into output at the specified scale, with
 // antialiasing. 0 is no coverage (transparent), 255 is fully covered (opaque).
 // *width & *height are filled out with the width & height of the bitmap,
 // which is stored left-to-right, top-to-bottom.
 // output has row spacing of 'out_stride' bytes. the bitmap
 // is clipped to out_w/out_h bytes. Call stbtt_GetGlyphBitmapBox to get the
 // width and height and positioning info for it first.
 
 STBTT_DEF void stbtt_MakeGlyphBitmapSubpixel(Arena a, const stbtt_fontinfo *info, unsigned char *output,
                                              int out_w, int out_h, int out_stride, float scale_x,
                                              float scale_y, float shift_x, float shift_y, int glyph);
 // same as stbtt_MakeGlyphBitmap, but you can specify a subpixel shift for the character
 
 STBTT_DEF void stbtt_MakeGlyphBitmapSubpixelPrefilter(Arena a, const stbtt_fontinfo *info,
                                                       unsigned char *output, int out_w, int out_h,
                                                       int out_stride, float scale_x, float scale_y,
                                                       float shift_x, float shift_y, int oversample_x,
                                                       int oversample_y, float *sub_x, float *sub_y,
                                                       int glyph);
 // same as stbtt_MakeGlyphBitmapSubpixel, but prefiltering is performed for improved quality on small fonts
 
 STBTT_DEF void stbtt_GetGlyphBitmapBoxSubpixel(const stbtt_fontinfo *font, int glyph, float scale_x,
                                                float scale_y,float shift_x, float shift_y,
                                                int *ix0, int *iy0, int *ix1, int *iy1);
 // get the bbox of the bitmap centered around the glyph origin; so the
 // bitmap width is ix1-ix0, height is iy1-iy0, and location to place
 // the bitmap top left is (leftSideBearing*scale,iy0).
 // (Note that the bitmap uses y-increases-down, but the shape uses
 // y-increases-up, so GlyphBitmapBox and GlyphBox are inverted.)
 
 
 // @TODO: don't expose this structure
 typedef struct
 {
    int w,h,stride;
    unsigned char *pixels;
 } stbtt__bitmap;
 
 // rasterize a shape with quadratic beziers into a bitmap
 STBTT_DEF void stbtt_Rasterize(Arena a, stbtt__bitmap *result,        // 1-channel bitmap to draw into
                                float flatness_in_pixels,     // allowable error of curve in pixels
                                stbtt_vertex *vertices,       // array of vertices defining shape
                                int num_verts,                // number of vertices in above array
                                float scale_x, float scale_y, // scale applied to input vertices
                                float shift_x, float shift_y, // translation applied to input vertices
                                int x_off, int y_off,         // another translation applied to input
                                int invert);                  // if non-zero, vertically flip shape
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // Signed Distance Function (or Field) rendering
 
 STBTT_DEF unsigned char * stbtt_GetGlyphSDF(Arena *a, const stbtt_fontinfo *info, float scale,
                                             int glyph, int padding, unsigned char onedge_value,
                                             float pixel_dist_scale, int *width, int *height,
                                             int *xoff, int *yoff);
 // These functions compute a discretized SDF field for a single character, suitable for storing
 // in a single-channel texture, sampling with bilinear filtering, and testing against
 // larger than some threshold to produce scalable fonts.
 //        info              --  the font
 //        scale             --  controls the size of the resulting SDF bitmap, same as it would be creating a regular bitmap
 //        glyph/codepoint   --  the character to generate the SDF for
 //        padding           --  extra "pixels" around the character which are filled with the distance to the character (not 0),
 //                                 which allows effects like bit outlines
 //        onedge_value      --  value 0-255 to test the SDF against to reconstruct the character (i.e. the isocontour of the character)
 //        pixel_dist_scale  --  what value the SDF should increase by when moving one SDF "pixel" away from the edge (on the 0..255 scale)
 //                                 if positive, > onedge_value is inside; if negative, < onedge_value is inside
 //        width,height      --  output height & width of the SDF bitmap (including padding)
 //        xoff,yoff         --  output origin of the character
 //        return value      --  a 2D array of bytes 0..255, width*height in size
 //
 // pixel_dist_scale & onedge_value are a scale & bias that allows you to make
 // optimal use of the limited 0..255 for your application, trading off precision
 // and special effects. SDF values outside the range 0..255 are clamped to 0..255.
 //
 // Example:
 //      scale = stbtt_ScaleForPixelHeight(22)
 //      padding = 5
 //      onedge_value = 180
 //      pixel_dist_scale = 180/5.0 = 36.0
 //
 //      This will create an SDF bitmap in which the character is about 22 pixels
 //      high but the whole bitmap is about 22+5+5=32 pixels high. To produce a filled
 //      shape, sample the SDF at each pixel and fill the pixel if the SDF value
 //      is greater than or equal to 180/255. (You'll actually want to antialias,
 //      which is beyond the scope of this example.) Additionally, you can compute
 //      offset outlines (e.g. to stroke the character border inside & outside,
 //      or only outside). For example, to fill outside the character up to 3 SDF
 //      pixels, you would compare against (180-36.0*3)/255 = 72/255. The above
 //      choice of variables maps a range from 5 pixels outside the shape to
 //      2 pixels inside the shape to 0..255; this is intended primarily for apply
 //      outside effects only (the interior range is needed to allow proper
 //      antialiasing of the font at *smaller* sizes)
 //
 // The function computes the SDF analytically at each SDF pixel, not by e.g.
 // building a higher-res bitmap and approximating it. In theory the quality
 // should be as high as possible for an SDF of this size & representation, but
 // unclear if this is true in practice (perhaps building a higher-res bitmap
 // and computing from that can allow drop-out prevention).
 //
 // The algorithm has not been optimized at all, so expect it to be slow
 // if computing lots of characters or very large sizes.
 
 
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // Finding the right font...
 //
 // You should really just solve this offline, keep your own tables
 // of what font is what, and don't try to get it out of the .ttf file.
 // That's because getting it out of the .ttf file is really hard, because
 // the names in the file can appear in many possible encodings, in many
 // possible languages, and e.g. if you need a case-insensitive comparison,
 // the details of that depend on the encoding & language in a complex way
 // (actually underspecified in truetype, but also gigantic).
 //
 // But you can use the provided functions in two possible ways:
 //     stbtt_FindMatchingFont() will use *case-sensitive* comparisons on
 //             unicode-encoded names to try to find the font you want;
 //             you can run this before calling stbtt_InitFont()
 //
 //     stbtt_GetFontNameString() lets you get any of the various strings
 //             from the file yourself and do your own comparisons on them.
 //             You have to have called stbtt_InitFont() first.
 
 
 STBTT_DEF int stbtt_FindMatchingFont(unsigned char *fontdata, s8 name, int flags);
 // returns the offset (not index) of the font that matches, or -1 if none
 //   if you use STBTT_MACSTYLE_DONTCARE, use a font name like "Arial Bold".
 //   if you use any other flag, use a font name like "Arial"; this checks
 //     the 'macStyle' header field; i don't know if fonts set this consistently
 #define STBTT_MACSTYLE_DONTCARE     0
 #define STBTT_MACSTYLE_BOLD         1
 #define STBTT_MACSTYLE_ITALIC       2
 #define STBTT_MACSTYLE_UNDERSCORE   4
 #define STBTT_MACSTYLE_NONE         8   // <= not same as 0, this makes us check the bitfield is 0
 
 STBTT_DEF int stbtt_CompareUTF8toUTF16_bigendian(s8 s1, s8 s2);
 // returns 1/0 whether the first string interpreted as utf8 is identical to
 // the second string interpreted as big-endian utf16... useful for strings from next func
 
 STBTT_DEF const char *stbtt_GetFontNameString(const stbtt_fontinfo *font, int *length, int platformID, int encodingID, int languageID, int nameID);
 // returns the string (which may be big-endian double byte, e.g. for unicode)
 // and puts the length in bytes in *length.
 //
 // some of the values for the IDs are below; for more see the truetype spec:
 //     http://developer.apple.com/textfonts/TTRefMan/RM06/Chap6name.html
 //     http://www.microsoft.com/typography/otspec/name.htm
 
 enum { // platformID
    STBTT_PLATFORM_ID_UNICODE   =0,
    STBTT_PLATFORM_ID_MAC       =1,
    STBTT_PLATFORM_ID_ISO       =2,
    STBTT_PLATFORM_ID_MICROSOFT =3
 };
 
 enum { // encodingID for STBTT_PLATFORM_ID_UNICODE
    STBTT_UNICODE_EID_UNICODE_1_0    =0,
    STBTT_UNICODE_EID_UNICODE_1_1    =1,
    STBTT_UNICODE_EID_ISO_10646      =2,
    STBTT_UNICODE_EID_UNICODE_2_0_BMP=3,
    STBTT_UNICODE_EID_UNICODE_2_0_FULL=4
 };
 
 enum { // encodingID for STBTT_PLATFORM_ID_MICROSOFT
    STBTT_MS_EID_SYMBOL        =0,
    STBTT_MS_EID_UNICODE_BMP   =1,
    STBTT_MS_EID_SHIFTJIS      =2,
    STBTT_MS_EID_UNICODE_FULL  =10
 };
 
 enum { // encodingID for STBTT_PLATFORM_ID_MAC; same as Script Manager codes
    STBTT_MAC_EID_ROMAN        =0,   STBTT_MAC_EID_ARABIC       =4,
    STBTT_MAC_EID_JAPANESE     =1,   STBTT_MAC_EID_HEBREW       =5,
    STBTT_MAC_EID_CHINESE_TRAD =2,   STBTT_MAC_EID_GREEK        =6,
    STBTT_MAC_EID_KOREAN       =3,   STBTT_MAC_EID_RUSSIAN      =7
 };
 
 enum { // languageID for STBTT_PLATFORM_ID_MICROSOFT; same as LCID...
        // problematic because there are e.g. 16 english LCIDs and 16 arabic LCIDs
    STBTT_MS_LANG_ENGLISH     =0x0409,   STBTT_MS_LANG_ITALIAN     =0x0410,
    STBTT_MS_LANG_CHINESE     =0x0804,   STBTT_MS_LANG_JAPANESE    =0x0411,
    STBTT_MS_LANG_DUTCH       =0x0413,   STBTT_MS_LANG_KOREAN      =0x0412,
    STBTT_MS_LANG_FRENCH      =0x040c,   STBTT_MS_LANG_RUSSIAN     =0x0419,
    STBTT_MS_LANG_GERMAN      =0x0407,   STBTT_MS_LANG_SPANISH     =0x0409,
    STBTT_MS_LANG_HEBREW      =0x040d,   STBTT_MS_LANG_SWEDISH     =0x041D
 };
 
 enum { // languageID for STBTT_PLATFORM_ID_MAC
    STBTT_MAC_LANG_ENGLISH      =0 ,   STBTT_MAC_LANG_JAPANESE     =11,
    STBTT_MAC_LANG_ARABIC       =12,   STBTT_MAC_LANG_KOREAN       =23,
    STBTT_MAC_LANG_DUTCH        =4 ,   STBTT_MAC_LANG_RUSSIAN      =32,
    STBTT_MAC_LANG_FRENCH       =1 ,   STBTT_MAC_LANG_SPANISH      =6 ,
    STBTT_MAC_LANG_GERMAN       =2 ,   STBTT_MAC_LANG_SWEDISH      =5 ,
    STBTT_MAC_LANG_HEBREW       =10,   STBTT_MAC_LANG_CHINESE_SIMPLIFIED =33,
    STBTT_MAC_LANG_ITALIAN      =3 ,   STBTT_MAC_LANG_CHINESE_TRAD =19
 };
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // __STB_INCLUDE_STB_TRUETYPE_H__
 
 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
 ////
 ////   IMPLEMENTATION
 ////
 ////
 
 #ifdef STB_TRUETYPE_IMPLEMENTATION
 
 #ifndef STBTT_MAX_OVERSAMPLE
 #define STBTT_MAX_OVERSAMPLE   8
 #endif
 
 #if STBTT_MAX_OVERSAMPLE > 255
 #error "STBTT_MAX_OVERSAMPLE cannot be > 255"
 #endif
 
 typedef int stbtt__test_oversample_pow2[(STBTT_MAX_OVERSAMPLE & (STBTT_MAX_OVERSAMPLE-1)) == 0 ? 1 : -1];
 
 #ifndef STBTT_RASTERIZER_VERSION
 #define STBTT_RASTERIZER_VERSION 2
 #endif
 
 #define STBTT__NOTUSED(v)  (void)(v)
 
 //////////////////////////////////////////////////////////////////////////
 //
 // stbtt__buf helpers to parse data from file
 //
 
 static stbtt_uint8 stbtt__buf_get8(stbtt__buf *b)
 {
    if (b->cursor >= b->size)
       return 0;
    return b->data[b->cursor++];
 }
 
 static stbtt_uint8 stbtt__buf_peek8(stbtt__buf *b)
 {
    if (b->cursor >= b->size)
       return 0;
    return b->data[b->cursor];
 }
 
 static void stbtt__buf_seek(stbtt__buf *b, int o)
 {
    STBTT_assert(!(o > b->size || o < 0));
    b->cursor = (o > b->size || o < 0) ? b->size : o;
 }
 
 static void stbtt__buf_skip(stbtt__buf *b, int o)
 {
    stbtt__buf_seek(b, b->cursor + o);
 }
 
 static stbtt_uint32 stbtt__buf_get(stbtt__buf *b, int n)
 {
    stbtt_uint32 v = 0;
    int i;
    STBTT_assert(n >= 1 && n <= 4);
    for (i = 0; i < n; i++)
       v = (v << 8) | stbtt__buf_get8(b);
    return v;
 }
 
 static stbtt__buf stbtt__new_buf(const void *p, size_t size)
 {
    stbtt__buf r;
    STBTT_assert(size < 0x40000000);
    r.data = (stbtt_uint8*) p;
    r.size = (int) size;
    r.cursor = 0;
    return r;
 }
 
 #define stbtt__buf_get16(b)  stbtt__buf_get((b), 2)
 #define stbtt__buf_get32(b)  stbtt__buf_get((b), 4)
 
 static stbtt__buf stbtt__buf_range(const stbtt__buf *b, int o, int s)
 {
    stbtt__buf r = stbtt__new_buf(NULL, 0);
    if (o < 0 || s < 0 || o > b->size || s > b->size - o) return r;
    r.data = b->data + o;
    r.size = s;
    return r;
 }
 
 static stbtt__buf stbtt__cff_get_index(stbtt__buf *b)
 {
    int count, start, offsize;
    start = b->cursor;
    count = stbtt__buf_get16(b);
    if (count) {
       offsize = stbtt__buf_get8(b);
       STBTT_assert(offsize >= 1 && offsize <= 4);
       stbtt__buf_skip(b, offsize * count);
       stbtt__buf_skip(b, stbtt__buf_get(b, offsize) - 1);
    }
    return stbtt__buf_range(b, start, b->cursor - start);
 }
 
 static stbtt_uint32 stbtt__cff_int(stbtt__buf *b)
 {
    int b0 = stbtt__buf_get8(b);
    if (b0 >= 32 && b0 <= 246)       return b0 - 139;
    else if (b0 >= 247 && b0 <= 250) return (b0 - 247)*256 + stbtt__buf_get8(b) + 108;
    else if (b0 >= 251 && b0 <= 254) return -(b0 - 251)*256 - stbtt__buf_get8(b) - 108;
    else if (b0 == 28)               return stbtt__buf_get16(b);
    else if (b0 == 29)               return stbtt__buf_get32(b);
    STBTT_assert(0);
    return 0;
 }
 
 static void stbtt__cff_skip_operand(stbtt__buf *b) {
    int v, b0 = stbtt__buf_peek8(b);
    STBTT_assert(b0 >= 28);
    if (b0 == 30) {
       stbtt__buf_skip(b, 1);
       while (b->cursor < b->size) {
          v = stbtt__buf_get8(b);
          if ((v & 0xF) == 0xF || (v >> 4) == 0xF)
             break;
       }
    } else {
       stbtt__cff_int(b);
    }
 }
 
 static stbtt__buf stbtt__dict_get(stbtt__buf *b, int key)
 {
    stbtt__buf_seek(b, 0);
    while (b->cursor < b->size) {
       int start = b->cursor, end, op;
       while (stbtt__buf_peek8(b) >= 28)
          stbtt__cff_skip_operand(b);
       end = b->cursor;
       op = stbtt__buf_get8(b);
       if (op == 12)  op = stbtt__buf_get8(b) | 0x100;
       if (op == key) return stbtt__buf_range(b, start, end-start);
    }
    return stbtt__buf_range(b, 0, 0);
 }
 
 static void stbtt__dict_get_ints(stbtt__buf *b, int key, int outcount, stbtt_uint32 *out)
 {
    int i;
    stbtt__buf operands = stbtt__dict_get(b, key);
    for (i = 0; i < outcount && operands.cursor < operands.size; i++)
       out[i] = stbtt__cff_int(&operands);
 }
 
 static int stbtt__cff_index_count(stbtt__buf *b)
 {
    stbtt__buf_seek(b, 0);
    return stbtt__buf_get16(b);
 }
 
 static stbtt__buf stbtt__cff_index_get(stbtt__buf b, int i)
 {
    int count, offsize, start, end;
    stbtt__buf_seek(&b, 0);
    count = stbtt__buf_get16(&b);
    offsize = stbtt__buf_get8(&b);
    STBTT_assert(i >= 0 && i < count);
    STBTT_assert(offsize >= 1 && offsize <= 4);
    stbtt__buf_skip(&b, i*offsize);
    start = stbtt__buf_get(&b, offsize);
    end = stbtt__buf_get(&b, offsize);
    return stbtt__buf_range(&b, 2+(count+1)*offsize+start, end - start);
 }
 
 //////////////////////////////////////////////////////////////////////////
 //
 // accessors to parse data from file
 //
 
 // on platforms that don't allow misaligned reads, if we want to allow
 // truetype fonts that aren't padded to alignment, define ALLOW_UNALIGNED_TRUETYPE
 
 #define ttBYTE(p)     (* (stbtt_uint8 *) (p))
 #define ttCHAR(p)     (* (stbtt_int8 *) (p))
 #define ttFixed(p)    ttLONG(p)
 
 static stbtt_uint16 ttUSHORT(stbtt_uint8 *p) { return p[0]*256 + p[1]; }
 static stbtt_int16 ttSHORT(stbtt_uint8 *p)   { return p[0]*256 + p[1]; }
 static stbtt_uint32 ttULONG(stbtt_uint8 *p)  { return (p[0]<<24) + (p[1]<<16) + (p[2]<<8) + p[3]; }
 static stbtt_int32 ttLONG(stbtt_uint8 *p)    { return (p[0]<<24) + (p[1]<<16) + (p[2]<<8) + p[3]; }
 
 #define stbtt_tag4(p,c0,c1,c2,c3) ((p)[0] == (c0) && (p)[1] == (c1) && (p)[2] == (c2) && (p)[3] == (c3))
 #define stbtt_tag(p,str)           stbtt_tag4(p,str[0],str[1],str[2],str[3])
 
 static int stbtt__isfont(stbtt_uint8 *font)
 {
    // check the version number
    if (stbtt_tag4(font, '1',0,0,0))  return 1; // TrueType 1
    if (stbtt_tag(font, "typ1"))   return 1; // TrueType with type 1 font -- we don't support this!
    if (stbtt_tag(font, "OTTO"))   return 1; // OpenType with CFF
    if (stbtt_tag4(font, 0,1,0,0)) return 1; // OpenType 1.0
    if (stbtt_tag(font, "true"))   return 1; // Apple specification for TrueType fonts
    return 0;
 }
 
 // @OPTIMIZE: binary search
 static stbtt_uint32 stbtt__find_table(stbtt_uint8 *data, stbtt_uint32 fontstart, const char *tag)
 {
    stbtt_int32 num_tables = ttUSHORT(data+fontstart+4);
    stbtt_uint32 tabledir = fontstart + 12;
    stbtt_int32 i;
    for (i=0; i < num_tables; ++i) {
       stbtt_uint32 loc = tabledir + 16*i;
       if (stbtt_tag(data+loc+0, tag))
          return ttULONG(data+loc+8);
    }
    return 0;
 }
 
 STBTT_DEF int stbtt_GetFontOffsetForIndex(unsigned char *font_collection, int index)
 {
    // if it's just a font, there's only one valid index
    if (stbtt__isfont(font_collection))
       return index == 0 ? 0 : -1;
 
    // check if it's a TTC
    if (stbtt_tag(font_collection, "ttcf")) {
       // version 1?
       if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
          stbtt_int32 n = ttLONG(font_collection+8);
          if (index >= n)
             return -1;
          return ttULONG(font_collection+12+index*4);
       }
    }
    return -1;
 }
 
 STBTT_DEF int stbtt_GetNumberOfFonts(unsigned char *font_collection)
 {
    // if it's just a font, there's only one valid font
    if (stbtt__isfont(font_collection))
       return 1;
 
    // check if it's a TTC
    if (stbtt_tag(font_collection, "ttcf")) {
       // version 1?
       if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
          return ttLONG(font_collection+8);
       }
    }
    return 0;
 }
 
 static stbtt__buf stbtt__get_subrs(stbtt__buf cff, stbtt__buf fontdict)
 {
    stbtt_uint32 subrsoff = 0, private_loc[2] = { 0, 0 };
    stbtt__buf pdict;
    stbtt__dict_get_ints(&fontdict, 18, 2, private_loc);
    if (!private_loc[1] || !private_loc[0]) return stbtt__new_buf(NULL, 0);
    pdict = stbtt__buf_range(&cff, private_loc[1], private_loc[0]);
    stbtt__dict_get_ints(&pdict, 19, 1, &subrsoff);
    if (!subrsoff) return stbtt__new_buf(NULL, 0);
    stbtt__buf_seek(&cff, private_loc[1]+subrsoff);
    return stbtt__cff_get_index(&cff);
 }
 
 // since most people won't use this, find this table the first time it's needed
 static int stbtt__get_svg(stbtt_fontinfo *info)
 {
    stbtt_uint32 t;
    if (info->svg < 0) {
       t = stbtt__find_table(info->data, info->fontstart, "SVG ");
       if (t) {
          stbtt_uint32 offset = ttULONG(info->data + t + 2);
          info->svg = t + offset;
       } else {
          info->svg = 0;
       }
    }
    return info->svg;
 }
 
 STBTT_DEF int stbtt_InitFont(stbtt_fontinfo *info, unsigned char *data, int fontstart)
 {
    stbtt_uint32 cmap, t;
    stbtt_int32 i,numTables;
 
    info->data = data;
    info->fontstart = fontstart;
    info->cff = stbtt__new_buf(NULL, 0);
 
    cmap = stbtt__find_table(data, fontstart, "cmap");       // required
    info->loca = stbtt__find_table(data, fontstart, "loca"); // required
    info->head = stbtt__find_table(data, fontstart, "head"); // required
    info->glyf = stbtt__find_table(data, fontstart, "glyf"); // required
    info->hhea = stbtt__find_table(data, fontstart, "hhea"); // required
    info->hmtx = stbtt__find_table(data, fontstart, "hmtx"); // required
    info->kern = stbtt__find_table(data, fontstart, "kern"); // not required
    info->gpos = stbtt__find_table(data, fontstart, "GPOS"); // not required
 
    if (!cmap || !info->head || !info->hhea || !info->hmtx)
       return 0;
    if (info->glyf) {
       // required for truetype
       if (!info->loca) return 0;
    } else {
       // initialization for CFF / Type2 fonts (OTF)
       stbtt__buf b, topdict, topdictidx;
       stbtt_uint32 cstype = 2, charstrings = 0, fdarrayoff = 0, fdselectoff = 0;
       stbtt_uint32 cff;
 
       cff = stbtt__find_table(data, fontstart, "CFF ");
       if (!cff) return 0;
 
       info->fontdicts = stbtt__new_buf(NULL, 0);
       info->fdselect = stbtt__new_buf(NULL, 0);
 
       // @TODO this should use size from table (not 512MB)
       info->cff = stbtt__new_buf(data+cff, 512*1024*1024);
       b = info->cff;
 
       // read the header
       stbtt__buf_skip(&b, 2);
       stbtt__buf_seek(&b, stbtt__buf_get8(&b)); // hdrsize
 
       // @TODO the name INDEX could list multiple fonts,
       // but we just use the first one.
       stbtt__cff_get_index(&b);  // name INDEX
       topdictidx = stbtt__cff_get_index(&b);
       topdict = stbtt__cff_index_get(topdictidx, 0);
       stbtt__cff_get_index(&b);  // string INDEX
       info->gsubrs = stbtt__cff_get_index(&b);
 
       stbtt__dict_get_ints(&topdict, 17, 1, &charstrings);
       stbtt__dict_get_ints(&topdict, 0x100 | 6, 1, &cstype);
       stbtt__dict_get_ints(&topdict, 0x100 | 36, 1, &fdarrayoff);
       stbtt__dict_get_ints(&topdict, 0x100 | 37, 1, &fdselectoff);
       info->subrs = stbtt__get_subrs(b, topdict);
 
       // we only support Type 2 charstrings
       if (cstype != 2) return 0;
       if (charstrings == 0) return 0;
 
       if (fdarrayoff) {
          // looks like a CID font
          if (!fdselectoff) return 0;
          stbtt__buf_seek(&b, fdarrayoff);
          info->fontdicts = stbtt__cff_get_index(&b);
          info->fdselect = stbtt__buf_range(&b, fdselectoff, b.size-fdselectoff);
       }
 
       stbtt__buf_seek(&b, charstrings);
       info->charstrings = stbtt__cff_get_index(&b);
    }
 
    t = stbtt__find_table(data, fontstart, "maxp");
    if (t)
       info->numGlyphs = ttUSHORT(data+t+4);
    else
       info->numGlyphs = 0xffff;
 
    info->svg = -1;
 
    // find a cmap encoding table we understand *now* to avoid searching
    // later. (todo: could make this installable)
    // the same regardless of glyph.
    numTables = ttUSHORT(data + cmap + 2);
    info->index_map = 0;
    for (i=0; i < numTables; ++i) {
       stbtt_uint32 encoding_record = cmap + 4 + 8 * i;
       // find an encoding we understand:
       switch(ttUSHORT(data+encoding_record)) {
          case STBTT_PLATFORM_ID_MICROSOFT:
             switch (ttUSHORT(data+encoding_record+2)) {
                case STBTT_MS_EID_UNICODE_BMP:
                case STBTT_MS_EID_UNICODE_FULL:
                   // MS/Unicode
                   info->index_map = cmap + ttULONG(data+encoding_record+4);
                   break;
             }
             break;
         case STBTT_PLATFORM_ID_UNICODE:
             // Mac/iOS has these
             // all the encodingIDs are unicode, so we don't bother to check it
             info->index_map = cmap + ttULONG(data+encoding_record+4);
             break;
       }
    }
    if (info->index_map == 0)
       return 0;
 
    info->indexToLocFormat = ttUSHORT(data+info->head + 50);
    return 1;
 }
 
 STBTT_DEF int stbtt_FindGlyphIndex(const stbtt_fontinfo *info, int unicode_codepoint)
 {
    stbtt_uint8 *data = info->data;
    stbtt_uint32 index_map = info->index_map;
 
    stbtt_uint16 format = ttUSHORT(data + index_map + 0);
    if (format == 0) { // apple byte encoding
       stbtt_int32 bytes = ttUSHORT(data + index_map + 2);
       if (unicode_codepoint < bytes-6)
          return ttBYTE(data + index_map + 6 + unicode_codepoint);
       return 0;
    } else if (format == 6) {
       stbtt_uint32 first = ttUSHORT(data + index_map + 6);
       stbtt_uint32 count = ttUSHORT(data + index_map + 8);
       if ((stbtt_uint32) unicode_codepoint >= first && (stbtt_uint32) unicode_codepoint < first+count)
          return ttUSHORT(data + index_map + 10 + (unicode_codepoint - first)*2);
       return 0;
    } else if (format == 2) {
       STBTT_assert(0); // @TODO: high-byte mapping for japanese/chinese/korean
       return 0;
    } else if (format == 4) { // standard mapping for windows fonts: binary search collection of ranges
       stbtt_uint16 segcount = ttUSHORT(data+index_map+6) >> 1;
       stbtt_uint16 searchRange = ttUSHORT(data+index_map+8) >> 1;
       stbtt_uint16 entrySelector = ttUSHORT(data+index_map+10);
       stbtt_uint16 rangeShift = ttUSHORT(data+index_map+12) >> 1;
 
       // do a binary search of the segments
       stbtt_uint32 endCount = index_map + 14;
       stbtt_uint32 search = endCount;
 
       if (unicode_codepoint > 0xffff)
          return 0;
 
       // they lie from endCount .. endCount + segCount
       // but searchRange is the nearest power of two, so...
       if (unicode_codepoint >= ttUSHORT(data + search + rangeShift*2))
          search += rangeShift*2;
 
       // now decrement to bias correctly to find smallest
       search -= 2;
       while (entrySelector) {
          stbtt_uint16 end;
          searchRange >>= 1;
          end = ttUSHORT(data + search + searchRange*2);
          if (unicode_codepoint > end)
             search += searchRange*2;
          --entrySelector;
       }
       search += 2;
 
       {
          stbtt_uint16 offset, start, last;
          stbtt_uint16 item = (stbtt_uint16) ((search - endCount) >> 1);
 
          start = ttUSHORT(data + index_map + 14 + segcount*2 + 2 + 2*item);
          last = ttUSHORT(data + endCount + 2*item);
          if (unicode_codepoint < start || unicode_codepoint > last)
             return 0;
 
          offset = ttUSHORT(data + index_map + 14 + segcount*6 + 2 + 2*item);
          if (offset == 0)
             return (stbtt_uint16) (unicode_codepoint + ttSHORT(data + index_map + 14 + segcount*4 + 2 + 2*item));
 
          return ttUSHORT(data + offset + (unicode_codepoint-start)*2 + index_map + 14 + segcount*6 + 2 + 2*item);
       }
    } else if (format == 12 || format == 13) {
       stbtt_uint32 ngroups = ttULONG(data+index_map+12);
       stbtt_int32 low,high;
       low = 0; high = (stbtt_int32)ngroups;
       // Binary search the right group.
       while (low < high) {
          stbtt_int32 mid = low + ((high-low) >> 1); // rounds down, so low <= mid < high
          stbtt_uint32 start_char = ttULONG(data+index_map+16+mid*12);
          stbtt_uint32 end_char = ttULONG(data+index_map+16+mid*12+4);
          if ((stbtt_uint32) unicode_codepoint < start_char)
             high = mid;
          else if ((stbtt_uint32) unicode_codepoint > end_char)
             low = mid+1;
          else {
             stbtt_uint32 start_glyph = ttULONG(data+index_map+16+mid*12+8);
             if (format == 12)
                return start_glyph + unicode_codepoint-start_char;
             else // format == 13
                return start_glyph;
          }
       }
       return 0; // not found
    }
    // @TODO
    STBTT_assert(0);
    return 0;
 }
 
 static void stbtt_setvertex(stbtt_vertex *v, stbtt_uint8 type, stbtt_int32 x, stbtt_int32 y, stbtt_int32 cx, stbtt_int32 cy)
 {
    v->type = type;
    v->x = (stbtt_int16) x;
    v->y = (stbtt_int16) y;
    v->cx = (stbtt_int16) cx;
    v->cy = (stbtt_int16) cy;
 }
 
 static int stbtt__GetGlyfOffset(const stbtt_fontinfo *info, int glyph_index)
 {
    int g1,g2;
 
    STBTT_assert(!info->cff.size);
 
    if (glyph_index >= info->numGlyphs) return -1; // glyph index out of range
    if (info->indexToLocFormat >= 2)    return -1; // unknown index->glyph map format
 
    if (info->indexToLocFormat == 0) {
       g1 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2) * 2;
       g2 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2 + 2) * 2;
    } else {
       g1 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4);
       g2 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4 + 4);
    }
 
    return g1==g2 ? -1 : g1; // if length is 0, return -1
 }
 
 static int stbtt__GetGlyphInfoT2(const stbtt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1);
 
 STBTT_DEF int stbtt_GetGlyphBox(const stbtt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1)
 {
    if (info->cff.size) {
       stbtt__GetGlyphInfoT2(info, glyph_index, x0, y0, x1, y1);
    } else {
       int g = stbtt__GetGlyfOffset(info, glyph_index);
       if (g < 0) return 0;
 
       if (x0) *x0 = ttSHORT(info->data + g + 2);
       if (y0) *y0 = ttSHORT(info->data + g + 4);
       if (x1) *x1 = ttSHORT(info->data + g + 6);
       if (y1) *y1 = ttSHORT(info->data + g + 8);
    }
    return 1;
 }
 
 STBTT_DEF int stbtt_IsGlyphEmpty(const stbtt_fontinfo *info, int glyph_index)
 {
    stbtt_int16 numberOfContours;
    int g;
    if (info->cff.size)
       return stbtt__GetGlyphInfoT2(info, glyph_index, NULL, NULL, NULL, NULL) == 0;
    g = stbtt__GetGlyfOffset(info, glyph_index);
    if (g < 0) return 1;
    numberOfContours = ttSHORT(info->data + g);
    return numberOfContours == 0;
 }
 
 static int stbtt__close_shape(stbtt_vertex *vertices, int num_vertices, int was_off, int start_off,
     stbtt_int32 sx, stbtt_int32 sy, stbtt_int32 scx, stbtt_int32 scy, stbtt_int32 cx, stbtt_int32 cy)
 {
    if (start_off) {
       if (was_off)
          stbtt_setvertex(&vertices[num_vertices++], STBTT_vcurve, (cx+scx)>>1, (cy+scy)>>1, cx,cy);
       stbtt_setvertex(&vertices[num_vertices++], STBTT_vcurve, sx,sy,scx,scy);
    } else {
       if (was_off)
          stbtt_setvertex(&vertices[num_vertices++], STBTT_vcurve,sx,sy,cx,cy);
       else
          stbtt_setvertex(&vertices[num_vertices++], STBTT_vline,sx,sy,0,0);
    }
    return num_vertices;
 }
 
 static int stbtt__GetGlyphShapeTT(Arena *a, const stbtt_fontinfo *info, int glyph_index, stbtt_vertex **pvertices)
 {
    stbtt_int16 numberOfContours;
    stbtt_uint8 *endPtsOfContours;
    stbtt_uint8 *data = info->data;
    stbtt_vertex *vertices=0;
    int num_vertices=0;
    int g = stbtt__GetGlyfOffset(info, glyph_index);
 
    *pvertices = NULL;
 
    if (g < 0) return 0;
 
    numberOfContours = ttSHORT(data + g);
 
    if (numberOfContours > 0) {
       stbtt_uint8 flags=0,flagcount;
       stbtt_int32 ins, i,j=0,m,n, next_move, was_off=0, off, start_off=0;
       stbtt_int32 x,y,cx,cy,sx,sy, scx,scy;
       stbtt_uint8 *points;
       endPtsOfContours = (data + g + 10);
       ins = ttUSHORT(data + g + 10 + numberOfContours * 2);
       points = data + g + 10 + numberOfContours * 2 + 2 + ins;
 
       n = 1+ttUSHORT(endPtsOfContours + numberOfContours*2-2);
 
       m = n + 2*numberOfContours;  // a loose bound on how many vertices we might need
       vertices = alloc(a, typeof(*vertices), m);
 
       next_move = 0;
       flagcount=0;
 
       // in first pass, we load uninterpreted data into the allocated array
       // above, shifted to the end of the array so we won't overwrite it when
       // we create our final data starting from the front
 
       off = m - n; // starting offset for uninterpreted data, regardless of how m ends up being calculated
 
       // first load flags
 
       for (i=0; i < n; ++i) {
          if (flagcount == 0) {
             flags = *points++;
             if (flags & 8)
                flagcount = *points++;
          } else
             --flagcount;
          vertices[off+i].type = flags;
       }
 
       // now load x coordinates
       x=0;
       for (i=0; i < n; ++i) {
          flags = vertices[off+i].type;
          if (flags & 2) {
             stbtt_int16 dx = *points++;
             x += (flags & 16) ? dx : -dx; // ???
          } else {
             if (!(flags & 16)) {
                x = x + (stbtt_int16) (points[0]*256 + points[1]);
                points += 2;
             }
          }
          vertices[off+i].x = (stbtt_int16) x;
       }
 
       // now load y coordinates
       y=0;
       for (i=0; i < n; ++i) {
          flags = vertices[off+i].type;
          if (flags & 4) {
             stbtt_int16 dy = *points++;
             y += (flags & 32) ? dy : -dy; // ???
          } else {
             if (!(flags & 32)) {
                y = y + (stbtt_int16) (points[0]*256 + points[1]);
                points += 2;
             }
          }
          vertices[off+i].y = (stbtt_int16) y;
       }
 
       // now convert them to our format
       num_vertices=0;
       sx = sy = cx = cy = scx = scy = 0;
       for (i=0; i < n; ++i) {
          flags = vertices[off+i].type;
          x     = (stbtt_int16) vertices[off+i].x;
          y     = (stbtt_int16) vertices[off+i].y;
 
          if (next_move == i) {
             if (i != 0)
                num_vertices = stbtt__close_shape(vertices, num_vertices, was_off, start_off, sx,sy,scx,scy,cx,cy);
 
             // now start the new one
             start_off = !(flags & 1);
             if (start_off) {
                // if we start off with an off-curve point, then when we need to find a point on the curve
                // where we can start, and we need to save some state for when we wraparound.
                scx = x;
                scy = y;
                if (!(vertices[off+i+1].type & 1)) {
                   // next point is also a curve point, so interpolate an on-point curve
                   sx = (x + (stbtt_int32) vertices[off+i+1].x) >> 1;
                   sy = (y + (stbtt_int32) vertices[off+i+1].y) >> 1;
                } else {
                   // otherwise just use the next point as our start point
                   sx = (stbtt_int32) vertices[off+i+1].x;
                   sy = (stbtt_int32) vertices[off+i+1].y;
                   ++i; // we're using point i+1 as the starting point, so skip it
                }
             } else {
                sx = x;
                sy = y;
             }
             stbtt_setvertex(&vertices[num_vertices++], STBTT_vmove,sx,sy,0,0);
             was_off = 0;
             next_move = 1 + ttUSHORT(endPtsOfContours+j*2);
             ++j;
          } else {
             if (!(flags & 1)) { // if it's a curve
                if (was_off) // two off-curve control points in a row means interpolate an on-curve midpoint
                   stbtt_setvertex(&vertices[num_vertices++], STBTT_vcurve, (cx+x)>>1, (cy+y)>>1, cx, cy);
                cx = x;
                cy = y;
                was_off = 1;
             } else {
                if (was_off)
                   stbtt_setvertex(&vertices[num_vertices++], STBTT_vcurve, x,y, cx, cy);
                else
                   stbtt_setvertex(&vertices[num_vertices++], STBTT_vline, x,y,0,0);
                was_off = 0;
             }
          }
       }
       num_vertices = stbtt__close_shape(vertices, num_vertices, was_off, start_off, sx,sy,scx,scy,cx,cy);
    } else if (numberOfContours < 0) {
       // Compound shapes.
       int more = 1;
       stbtt_uint8 *comp = data + g + 10;
       num_vertices = 0;
       vertices = 0;
       while (more) {
          stbtt_uint16 flags, gidx;
          int comp_num_verts = 0, i;
          stbtt_vertex *comp_verts = 0, *tmp = 0;
          float mtx[6] = {1,0,0,1,0,0}, m, n;
 
          flags = ttSHORT(comp); comp+=2;
          gidx = ttSHORT(comp); comp+=2;
 
          if (flags & 2) { // XY values
             if (flags & 1) { // shorts
                mtx[4] = ttSHORT(comp); comp+=2;
                mtx[5] = ttSHORT(comp); comp+=2;
             } else {
                mtx[4] = ttCHAR(comp); comp+=1;
                mtx[5] = ttCHAR(comp); comp+=1;
             }
          }
          else {
             // @TODO handle matching point
             STBTT_assert(0);
          }
          if (flags & (1<<3)) { // WE_HAVE_A_SCALE
             mtx[0] = mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
             mtx[1] = mtx[2] = 0;
          } else if (flags & (1<<6)) { // WE_HAVE_AN_X_AND_YSCALE
             mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
             mtx[1] = mtx[2] = 0;
             mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
          } else if (flags & (1<<7)) { // WE_HAVE_A_TWO_BY_TWO
             mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
             mtx[1] = ttSHORT(comp)/16384.0f; comp+=2;
             mtx[2] = ttSHORT(comp)/16384.0f; comp+=2;
             mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
          }
 
          // Find transformation scales.
          m = (float) STBTT_sqrt(mtx[0]*mtx[0] + mtx[1]*mtx[1]);
          n = (float) STBTT_sqrt(mtx[2]*mtx[2] + mtx[3]*mtx[3]);
 
          // Get indexed glyph.
          comp_num_verts = stbtt_GetGlyphShape(a, info, gidx, &comp_verts);
          if (comp_num_verts > 0) {
             // Transform vertices.
             for (i = 0; i < comp_num_verts; ++i) {
                stbtt_vertex* v = &comp_verts[i];
                stbtt_vertex_type x,y;
                x=v->x; y=v->y;
                v->x = (stbtt_vertex_type)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
                v->y = (stbtt_vertex_type)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
                x=v->cx; y=v->cy;
                v->cx = (stbtt_vertex_type)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
                v->cy = (stbtt_vertex_type)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
             }
             // Append vertices.
             tmp = alloc(a, stbtt_vertex, num_vertices + comp_num_verts);
             if (num_vertices > 0 && vertices)
                mem_copy(vertices, tmp, num_vertices * sizeof(stbtt_vertex));
             mem_copy(comp_verts, tmp + num_vertices, comp_num_verts * sizeof(stbtt_vertex));
             vertices = tmp;
             num_vertices += comp_num_verts;
          }
          // More components ?
          more = flags & (1<<5);
       }
    } else {
       // numberOfCounters == 0, do nothing
    }
 
    *pvertices = vertices;
    return num_vertices;
 }
 
 typedef struct
 {
    int bounds;
    int started;
    float first_x, first_y;
    float x, y;
    stbtt_int32 min_x, max_x, min_y, max_y;
 
    stbtt_vertex *pvertices;
    int num_vertices;
 } stbtt__csctx;
 
 #define STBTT__CSCTX_INIT(bounds) {bounds,0, 0,0, 0,0, 0,0,0,0, NULL, 0}
 
 static void stbtt__track_vertex(stbtt__csctx *c, stbtt_int32 x, stbtt_int32 y)
 {
    if (x > c->max_x || !c->started) c->max_x = x;
    if (y > c->max_y || !c->started) c->max_y = y;
    if (x < c->min_x || !c->started) c->min_x = x;
    if (y < c->min_y || !c->started) c->min_y = y;
    c->started = 1;
 }
 
 static void stbtt__csctx_v(stbtt__csctx *c, stbtt_uint8 type, stbtt_int32 x, stbtt_int32 y, stbtt_int32 cx, stbtt_int32 cy, stbtt_int32 cx1, stbtt_int32 cy1)
 {
    if (c->bounds) {
       stbtt__track_vertex(c, x, y);
       if (type == STBTT_vcubic) {
          stbtt__track_vertex(c, cx, cy);
          stbtt__track_vertex(c, cx1, cy1);
       }
    } else {
       stbtt_setvertex(&c->pvertices[c->num_vertices], type, x, y, cx, cy);
       c->pvertices[c->num_vertices].cx1 = (stbtt_int16) cx1;
       c->pvertices[c->num_vertices].cy1 = (stbtt_int16) cy1;
    }
    c->num_vertices++;
 }
 
 static void stbtt__csctx_close_shape(stbtt__csctx *ctx)
 {
    if (ctx->first_x != ctx->x || ctx->first_y != ctx->y)
       stbtt__csctx_v(ctx, STBTT_vline, (int)ctx->first_x, (int)ctx->first_y, 0, 0, 0, 0);
 }
 
 static void stbtt__csctx_rmove_to(stbtt__csctx *ctx, float dx, float dy)
 {
    stbtt__csctx_close_shape(ctx);
    ctx->first_x = ctx->x = ctx->x + dx;
    ctx->first_y = ctx->y = ctx->y + dy;
    stbtt__csctx_v(ctx, STBTT_vmove, (int)ctx->x, (int)ctx->y, 0, 0, 0, 0);
 }
 
 static void stbtt__csctx_rline_to(stbtt__csctx *ctx, float dx, float dy)
 {
    ctx->x += dx;
    ctx->y += dy;
    stbtt__csctx_v(ctx, STBTT_vline, (int)ctx->x, (int)ctx->y, 0, 0, 0, 0);
 }
 
 static void stbtt__csctx_rccurve_to(stbtt__csctx *ctx, float dx1, float dy1, float dx2, float dy2, float dx3, float dy3)
 {
    float cx1 = ctx->x + dx1;
    float cy1 = ctx->y + dy1;
    float cx2 = cx1 + dx2;
    float cy2 = cy1 + dy2;
    ctx->x = cx2 + dx3;
    ctx->y = cy2 + dy3;
    stbtt__csctx_v(ctx, STBTT_vcubic, (int)ctx->x, (int)ctx->y, (int)cx1, (int)cy1, (int)cx2, (int)cy2);
 }
 
 static stbtt__buf stbtt__get_subr(stbtt__buf idx, int n)
 {
    int count = stbtt__cff_index_count(&idx);
    int bias = 107;
    if (count >= 33900)
       bias = 32768;
    else if (count >= 1240)
       bias = 1131;
    n += bias;
    if (n < 0 || n >= count)
       return stbtt__new_buf(NULL, 0);
    return stbtt__cff_index_get(idx, n);
 }
 
 static stbtt__buf stbtt__cid_get_glyph_subrs(const stbtt_fontinfo *info, int glyph_index)
 {
    stbtt__buf fdselect = info->fdselect;
    int nranges, start, end, v, fmt, fdselector = -1, i;
 
    stbtt__buf_seek(&fdselect, 0);
    fmt = stbtt__buf_get8(&fdselect);
    if (fmt == 0) {
       // untested
       stbtt__buf_skip(&fdselect, glyph_index);
       fdselector = stbtt__buf_get8(&fdselect);
    } else if (fmt == 3) {
       nranges = stbtt__buf_get16(&fdselect);
       start = stbtt__buf_get16(&fdselect);
       for (i = 0; i < nranges; i++) {
          v = stbtt__buf_get8(&fdselect);
          end = stbtt__buf_get16(&fdselect);
          if (glyph_index >= start && glyph_index < end) {
             fdselector = v;
             break;
          }
          start = end;
       }
    }
    if (fdselector == -1) stbtt__new_buf(NULL, 0);
    return stbtt__get_subrs(info->cff, stbtt__cff_index_get(info->fontdicts, fdselector));
 }
 
 static int stbtt__run_charstring(const stbtt_fontinfo *info, int glyph_index, stbtt__csctx *c)
 {
    int in_header = 1, maskbits = 0, subr_stack_height = 0, sp = 0, v, i, b0;
    int has_subrs = 0, clear_stack;
    float s[48];
    stbtt__buf subr_stack[10], subrs = info->subrs, b;
    float f;
 
 #define STBTT__CSERR(s) (0)
 
    // this currently ignores the initial width value, which isn't needed if we have hmtx
    b = stbtt__cff_index_get(info->charstrings, glyph_index);
    while (b.cursor < b.size) {
       i = 0;
       clear_stack = 1;
       b0 = stbtt__buf_get8(&b);
       switch (b0) {
       // @TODO implement hinting
       case 0x13: // hintmask
       case 0x14: // cntrmask
          if (in_header)
             maskbits += (sp / 2); // implicit "vstem"
          in_header = 0;
          stbtt__buf_skip(&b, (maskbits + 7) / 8);
          break;
 
       case 0x01: // hstem
       case 0x03: // vstem
       case 0x12: // hstemhm
       case 0x17: // vstemhm
          maskbits += (sp / 2);
          break;
 
       case 0x15: // rmoveto
          in_header = 0;
          if (sp < 2) return STBTT__CSERR("rmoveto stack");
          stbtt__csctx_rmove_to(c, s[sp-2], s[sp-1]);
          break;
       case 0x04: // vmoveto
          in_header = 0;
          if (sp < 1) return STBTT__CSERR("vmoveto stack");
          stbtt__csctx_rmove_to(c, 0, s[sp-1]);
          break;
       case 0x16: // hmoveto
          in_header = 0;
          if (sp < 1) return STBTT__CSERR("hmoveto stack");
          stbtt__csctx_rmove_to(c, s[sp-1], 0);
          break;
 
       case 0x05: // rlineto
          if (sp < 2) return STBTT__CSERR("rlineto stack");
          for (; i + 1 < sp; i += 2)
             stbtt__csctx_rline_to(c, s[i], s[i+1]);
          break;
 
       // hlineto/vlineto and vhcurveto/hvcurveto alternate horizontal and vertical
       // starting from a different place.
 
       case 0x07: // vlineto
          if (sp < 1) return STBTT__CSERR("vlineto stack");
          goto vlineto;
       case 0x06: // hlineto
          if (sp < 1) return STBTT__CSERR("hlineto stack");
          for (;;) {
             if (i >= sp) break;
             stbtt__csctx_rline_to(c, s[i], 0);
             i++;
       vlineto:
             if (i >= sp) break;
             stbtt__csctx_rline_to(c, 0, s[i]);
             i++;
          }
          break;
 
       case 0x1F: // hvcurveto
          if (sp < 4) return STBTT__CSERR("hvcurveto stack");
          goto hvcurveto;
       case 0x1E: // vhcurveto
          if (sp < 4) return STBTT__CSERR("vhcurveto stack");
          for (;;) {
             if (i + 3 >= sp) break;
             stbtt__csctx_rccurve_to(c, 0, s[i], s[i+1], s[i+2], s[i+3], (sp - i == 5) ? s[i + 4] : 0.0f);
             i += 4;
       hvcurveto:
             if (i + 3 >= sp) break;
             stbtt__csctx_rccurve_to(c, s[i], 0, s[i+1], s[i+2], (sp - i == 5) ? s[i+4] : 0.0f, s[i+3]);
             i += 4;
          }
          break;
 
       case 0x08: // rrcurveto
          if (sp < 6) return STBTT__CSERR("rcurveline stack");
          for (; i + 5 < sp; i += 6)
             stbtt__csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
          break;
 
       case 0x18: // rcurveline
          if (sp < 8) return STBTT__CSERR("rcurveline stack");
          for (; i + 5 < sp - 2; i += 6)
             stbtt__csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
          if (i + 1 >= sp) return STBTT__CSERR("rcurveline stack");
          stbtt__csctx_rline_to(c, s[i], s[i+1]);
          break;
 
       case 0x19: // rlinecurve
          if (sp < 8) return STBTT__CSERR("rlinecurve stack");
          for (; i + 1 < sp - 6; i += 2)
             stbtt__csctx_rline_to(c, s[i], s[i+1]);
          if (i + 5 >= sp) return STBTT__CSERR("rlinecurve stack");
          stbtt__csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
          break;
 
       case 0x1A: // vvcurveto
       case 0x1B: // hhcurveto
          if (sp < 4) return STBTT__CSERR("(vv|hh)curveto stack");
          f = 0.0;
          if (sp & 1) { f = s[i]; i++; }
          for (; i + 3 < sp; i += 4) {
             if (b0 == 0x1B)
                stbtt__csctx_rccurve_to(c, s[i], f, s[i+1], s[i+2], s[i+3], 0.0);
             else
                stbtt__csctx_rccurve_to(c, f, s[i], s[i+1], s[i+2], 0.0, s[i+3]);
             f = 0.0;
          }
          break;
 
       case 0x0A: // callsubr
          if (!has_subrs) {
             if (info->fdselect.size)
                subrs = stbtt__cid_get_glyph_subrs(info, glyph_index);
             has_subrs = 1;
          }
          // FALLTHROUGH
       case 0x1D: // callgsubr
          if (sp < 1) return STBTT__CSERR("call(g|)subr stack");
          v = (int) s[--sp];
          if (subr_stack_height >= 10) return STBTT__CSERR("recursion limit");
          subr_stack[subr_stack_height++] = b;
          b = stbtt__get_subr(b0 == 0x0A ? subrs : info->gsubrs, v);
          if (b.size == 0) return STBTT__CSERR("subr not found");
          b.cursor = 0;
          clear_stack = 0;
          break;
 
       case 0x0B: // return
          if (subr_stack_height <= 0) return STBTT__CSERR("return outside subr");
          b = subr_stack[--subr_stack_height];
          clear_stack = 0;
          break;
 
       case 0x0E: // endchar
          stbtt__csctx_close_shape(c);
          return 1;
 
       case 0x0C: { // two-byte escape
          float dx1, dx2, dx3, dx4, dx5, dx6, dy1, dy2, dy3, dy4, dy5, dy6;
          float dx, dy;
          int b1 = stbtt__buf_get8(&b);
          switch (b1) {
          // @TODO These "flex" implementations ignore the flex-depth and resolution,
          // and always draw beziers.
          case 0x22: // hflex
             if (sp < 7) return STBTT__CSERR("hflex stack");
             dx1 = s[0];
             dx2 = s[1];
             dy2 = s[2];
             dx3 = s[3];
             dx4 = s[4];
             dx5 = s[5];
             dx6 = s[6];
             stbtt__csctx_rccurve_to(c, dx1, 0, dx2, dy2, dx3, 0);
             stbtt__csctx_rccurve_to(c, dx4, 0, dx5, -dy2, dx6, 0);
             break;
 
          case 0x23: // flex
             if (sp < 13) return STBTT__CSERR("flex stack");
             dx1 = s[0];
             dy1 = s[1];
             dx2 = s[2];
             dy2 = s[3];
             dx3 = s[4];
             dy3 = s[5];
             dx4 = s[6];
             dy4 = s[7];
             dx5 = s[8];
             dy5 = s[9];
             dx6 = s[10];
             dy6 = s[11];
             //fd is s[12]
             stbtt__csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, dy3);
             stbtt__csctx_rccurve_to(c, dx4, dy4, dx5, dy5, dx6, dy6);
             break;
 
          case 0x24: // hflex1
             if (sp < 9) return STBTT__CSERR("hflex1 stack");
             dx1 = s[0];
             dy1 = s[1];
             dx2 = s[2];
             dy2 = s[3];
             dx3 = s[4];
             dx4 = s[5];
             dx5 = s[6];
             dy5 = s[7];
             dx6 = s[8];
             stbtt__csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, 0);
             stbtt__csctx_rccurve_to(c, dx4, 0, dx5, dy5, dx6, -(dy1+dy2+dy5));
             break;
 
          case 0x25: // flex1
             if (sp < 11) return STBTT__CSERR("flex1 stack");
             dx1 = s[0];
             dy1 = s[1];
             dx2 = s[2];
             dy2 = s[3];
             dx3 = s[4];
             dy3 = s[5];
             dx4 = s[6];
             dy4 = s[7];
             dx5 = s[8];
             dy5 = s[9];
             dx6 = dy6 = s[10];
             dx = dx1+dx2+dx3+dx4+dx5;
             dy = dy1+dy2+dy3+dy4+dy5;
             if (STBTT_fabs(dx) > STBTT_fabs(dy))
                dy6 = -dy;
             else
                dx6 = -dx;
             stbtt__csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, dy3);
             stbtt__csctx_rccurve_to(c, dx4, dy4, dx5, dy5, dx6, dy6);
             break;
 
          default:
             return STBTT__CSERR("unimplemented");
          }
       } break;
 
       default:
          if (b0 != 255 && b0 != 28 && b0 < 32)
             return STBTT__CSERR("reserved operator");
 
          // push immediate
          if (b0 == 255) {
             f = (float)(stbtt_int32)stbtt__buf_get32(&b) / 0x10000;
          } else {
             stbtt__buf_skip(&b, -1);
             f = (float)(stbtt_int16)stbtt__cff_int(&b);
          }
          if (sp >= 48) return STBTT__CSERR("push stack overflow");
          s[sp++] = f;
          clear_stack = 0;
          break;
       }
       if (clear_stack) sp = 0;
    }
    return STBTT__CSERR("no endchar");
 
 #undef STBTT__CSERR
 }
 
 static int stbtt__GetGlyphShapeT2(Arena *a, const stbtt_fontinfo *info, int glyph_index, stbtt_vertex **pvertices)
 {
    // runs the charstring twice, once to count and once to output (to avoid realloc)
    stbtt__csctx count_ctx = STBTT__CSCTX_INIT(1);
    stbtt__csctx output_ctx = STBTT__CSCTX_INIT(0);
    if (stbtt__run_charstring(info, glyph_index, &count_ctx)) {
       *pvertices = alloc(a, stbtt_vertex, count_ctx.num_vertices);
       output_ctx.pvertices = *pvertices;
       if (stbtt__run_charstring(info, glyph_index, &output_ctx)) {
          STBTT_assert(output_ctx.num_vertices == count_ctx.num_vertices);
          return output_ctx.num_vertices;
       }
    }
    *pvertices = NULL;
    return 0;
 }
 
 static int stbtt__GetGlyphInfoT2(const stbtt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1)
 {
    stbtt__csctx c = STBTT__CSCTX_INIT(1);
    int r = stbtt__run_charstring(info, glyph_index, &c);
    if (x0)  *x0 = r ? c.min_x : 0;
    if (y0)  *y0 = r ? c.min_y : 0;
    if (x1)  *x1 = r ? c.max_x : 0;
    if (y1)  *y1 = r ? c.max_y : 0;
    return r ? c.num_vertices : 0;
 }
 
 STBTT_DEF int stbtt_GetGlyphShape(Arena *a, const stbtt_fontinfo *info, int glyph_index, stbtt_vertex **pvertices)
 {
    if (!info->cff.size) return stbtt__GetGlyphShapeTT(a, info, glyph_index, pvertices);
    else                 return stbtt__GetGlyphShapeT2(a, info, glyph_index, pvertices);
 }
 
 STBTT_DEF void stbtt_GetGlyphHMetrics(const stbtt_fontinfo *info, int glyph_index, int *advanceWidth, int *leftSideBearing)
 {
    stbtt_uint16 numOfLongHorMetrics = ttUSHORT(info->data+info->hhea + 34);
    if (glyph_index < numOfLongHorMetrics) {
       if (advanceWidth)     *advanceWidth    = ttSHORT(info->data + info->hmtx + 4*glyph_index);
       if (leftSideBearing)  *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*glyph_index + 2);
    } else {
       if (advanceWidth)     *advanceWidth    = ttSHORT(info->data + info->hmtx + 4*(numOfLongHorMetrics-1));
       if (leftSideBearing)  *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*numOfLongHorMetrics + 2*(glyph_index - numOfLongHorMetrics));
    }
 }
 
 STBTT_DEF int  stbtt_GetKerningTableLength(const stbtt_fontinfo *info)
 {
    stbtt_uint8 *data = info->data + info->kern;
 
    // we only look at the first table. it must be 'horizontal' and format 0.
    if (!info->kern)
       return 0;
    if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
       return 0;
    if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
       return 0;
 
    return ttUSHORT(data+10);
 }
 
 STBTT_DEF int stbtt_GetKerningTable(const stbtt_fontinfo *info, stbtt_kerningentry* table, int table_length)
 {
    stbtt_uint8 *data = info->data + info->kern;
    int k, length;
 
    // we only look at the first table. it must be 'horizontal' and format 0.
    if (!info->kern)
       return 0;
    if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
       return 0;
    if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
       return 0;
 
    length = ttUSHORT(data+10);
    if (table_length < length)
       length = table_length;
 
    for (k = 0; k < length; k++)
    {
       table[k].glyph1 = ttUSHORT(data+18+(k*6));
       table[k].glyph2 = ttUSHORT(data+20+(k*6));
       table[k].advance = ttSHORT(data+22+(k*6));
    }
 
    return length;
 }
 
 static int stbtt__GetGlyphKernInfoAdvance(const stbtt_fontinfo *info, int glyph1, int glyph2)
 {
    stbtt_uint8 *data = info->data + info->kern;
    stbtt_uint32 needle, straw;
    int l, r, m;
 
    // we only look at the first table. it must be 'horizontal' and format 0.
    if (!info->kern)
       return 0;
    if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
       return 0;
    if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
       return 0;
 
    l = 0;
    r = ttUSHORT(data+10) - 1;
    needle = glyph1 << 16 | glyph2;
    while (l <= r) {
       m = (l + r) >> 1;
       straw = ttULONG(data+18+(m*6)); // note: unaligned read
       if (needle < straw)
          r = m - 1;
       else if (needle > straw)
          l = m + 1;
       else
          return ttSHORT(data+22+(m*6));
    }
    return 0;
 }
 
 static stbtt_int32 stbtt__GetCoverageIndex(stbtt_uint8 *coverageTable, int glyph)
 {
    stbtt_uint16 coverageFormat = ttUSHORT(coverageTable);
    switch (coverageFormat) {
       case 1: {
          stbtt_uint16 glyphCount = ttUSHORT(coverageTable + 2);
 
          // Binary search.
          stbtt_int32 l=0, r=glyphCount-1, m;
          int straw, needle=glyph;
          while (l <= r) {
             stbtt_uint8 *glyphArray = coverageTable + 4;
             stbtt_uint16 glyphID;
             m = (l + r) >> 1;
             glyphID = ttUSHORT(glyphArray + 2 * m);
             straw = glyphID;
             if (needle < straw)
                r = m - 1;
             else if (needle > straw)
                l = m + 1;
             else {
                return m;
             }
          }
          break;
       }
 
       case 2: {
          stbtt_uint16 rangeCount = ttUSHORT(coverageTable + 2);
          stbtt_uint8 *rangeArray = coverageTable + 4;
 
          // Binary search.
          stbtt_int32 l=0, r=rangeCount-1, m;
          int strawStart, strawEnd, needle=glyph;
          while (l <= r) {
             stbtt_uint8 *rangeRecord;
             m = (l + r) >> 1;
             rangeRecord = rangeArray + 6 * m;
             strawStart = ttUSHORT(rangeRecord);
             strawEnd = ttUSHORT(rangeRecord + 2);
             if (needle < strawStart)
                r = m - 1;
             else if (needle > strawEnd)
                l = m + 1;
             else {
                stbtt_uint16 startCoverageIndex = ttUSHORT(rangeRecord + 4);
                return startCoverageIndex + glyph - strawStart;
             }
          }
          break;
       }
 
       default: return -1; // unsupported
    }
 
    return -1;
 }
 
 static stbtt_int32  stbtt__GetGlyphClass(stbtt_uint8 *classDefTable, int glyph)
 {
    stbtt_uint16 classDefFormat = ttUSHORT(classDefTable);
    switch (classDefFormat)
    {
       case 1: {
          stbtt_uint16 startGlyphID = ttUSHORT(classDefTable + 2);
          stbtt_uint16 glyphCount = ttUSHORT(classDefTable + 4);
          stbtt_uint8 *classDef1ValueArray = classDefTable + 6;
 
          if (glyph >= startGlyphID && glyph < startGlyphID + glyphCount)
             return (stbtt_int32)ttUSHORT(classDef1ValueArray + 2 * (glyph - startGlyphID));
          break;
       }
 
       case 2: {
          stbtt_uint16 classRangeCount = ttUSHORT(classDefTable + 2);
          stbtt_uint8 *classRangeRecords = classDefTable + 4;
 
          // Binary search.
          stbtt_int32 l=0, r=classRangeCount-1, m;
          int strawStart, strawEnd, needle=glyph;
          while (l <= r) {
             stbtt_uint8 *classRangeRecord;
             m = (l + r) >> 1;
             classRangeRecord = classRangeRecords + 6 * m;
             strawStart = ttUSHORT(classRangeRecord);
             strawEnd = ttUSHORT(classRangeRecord + 2);
             if (needle < strawStart)
                r = m - 1;
             else if (needle > strawEnd)
                l = m + 1;
             else
                return (stbtt_int32)ttUSHORT(classRangeRecord + 4);
          }
          break;
       }
 
       default:
          return -1; // Unsupported definition type, return an error.
    }
 
    // "All glyphs not assigned to a class fall into class 0". (OpenType spec)
    return 0;
 }
 
 // Define to STBTT_assert(x) if you want to break on unimplemented formats.
 #define STBTT_GPOS_TODO_assert(x)
 
 static stbtt_int32 stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, int glyph1, int glyph2)
 {
    stbtt_uint16 lookupListOffset;
    stbtt_uint8 *lookupList;
    stbtt_uint16 lookupCount;
    stbtt_uint8 *data;
    stbtt_int32 i, sti;
 
    if (!info->gpos) return 0;
 
    data = info->data + info->gpos;
 
    if (ttUSHORT(data+0) != 1) return 0; // Major version 1
    if (ttUSHORT(data+2) != 0) return 0; // Minor version 0
 
    lookupListOffset = ttUSHORT(data+8);
    lookupList = data + lookupListOffset;
    lookupCount = ttUSHORT(lookupList);
 
    for (i=0; i<lookupCount; ++i) {
       stbtt_uint16 lookupOffset = ttUSHORT(lookupList + 2 + 2 * i);
       stbtt_uint8 *lookupTable = lookupList + lookupOffset;
 
       stbtt_uint16 lookupType = ttUSHORT(lookupTable);
       stbtt_uint16 subTableCount = ttUSHORT(lookupTable + 4);
       stbtt_uint8 *subTableOffsets = lookupTable + 6;
       if (lookupType != 2) // Pair Adjustment Positioning Subtable
          continue;
 
       for (sti=0; sti<subTableCount; sti++) {
          stbtt_uint16 subtableOffset = ttUSHORT(subTableOffsets + 2 * sti);
          stbtt_uint8 *table = lookupTable + subtableOffset;
          stbtt_uint16 posFormat = ttUSHORT(table);
          stbtt_uint16 coverageOffset = ttUSHORT(table + 2);
          stbtt_int32 coverageIndex = stbtt__GetCoverageIndex(table + coverageOffset, glyph1);
          if (coverageIndex == -1) continue;
 
          switch (posFormat) {
             case 1: {
                stbtt_int32 l, r, m;
                int straw, needle;
                stbtt_uint16 valueFormat1 = ttUSHORT(table + 4);
                stbtt_uint16 valueFormat2 = ttUSHORT(table + 6);
                if (valueFormat1 == 4 && valueFormat2 == 0) { // Support more formats?
                   stbtt_int32 valueRecordPairSizeInBytes = 2;
                   stbtt_uint16 pairSetCount = ttUSHORT(table + 8);
                   stbtt_uint16 pairPosOffset = ttUSHORT(table + 10 + 2 * coverageIndex);
                   stbtt_uint8 *pairValueTable = table + pairPosOffset;
                   stbtt_uint16 pairValueCount = ttUSHORT(pairValueTable);
                   stbtt_uint8 *pairValueArray = pairValueTable + 2;
 
                   if (coverageIndex >= pairSetCount) return 0;
 
                   needle=glyph2;
                   r=pairValueCount-1;
                   l=0;
 
                   // Binary search.
                   while (l <= r) {
                      stbtt_uint16 secondGlyph;
                      stbtt_uint8 *pairValue;
                      m = (l + r) >> 1;
                      pairValue = pairValueArray + (2 + valueRecordPairSizeInBytes) * m;
                      secondGlyph = ttUSHORT(pairValue);
                      straw = secondGlyph;
                      if (needle < straw)
                         r = m - 1;
                      else if (needle > straw)
                         l = m + 1;
                      else {
                         stbtt_int16 xAdvance = ttSHORT(pairValue + 2);
                         return xAdvance;
                      }
                   }
                } else
                   return 0;
                break;
             }
 
             case 2: {
                stbtt_uint16 valueFormat1 = ttUSHORT(table + 4);
                stbtt_uint16 valueFormat2 = ttUSHORT(table + 6);
                if (valueFormat1 == 4 && valueFormat2 == 0) { // Support more formats?
                   stbtt_uint16 classDef1Offset = ttUSHORT(table + 8);
                   stbtt_uint16 classDef2Offset = ttUSHORT(table + 10);
                   int glyph1class = stbtt__GetGlyphClass(table + classDef1Offset, glyph1);
                   int glyph2class = stbtt__GetGlyphClass(table + classDef2Offset, glyph2);
 
                   stbtt_uint16 class1Count = ttUSHORT(table + 12);
                   stbtt_uint16 class2Count = ttUSHORT(table + 14);
                   stbtt_uint8 *class1Records, *class2Records;
                   stbtt_int16 xAdvance;
 
                   if (glyph1class < 0 || glyph1class >= class1Count) return 0; // malformed
                   if (glyph2class < 0 || glyph2class >= class2Count) return 0; // malformed
 
                   class1Records = table + 16;
                   class2Records = class1Records + 2 * (glyph1class * class2Count);
                   xAdvance = ttSHORT(class2Records + 2 * glyph2class);
                   return xAdvance;
                } else
                   return 0;
                break;
             }
 
             default:
                return 0; // Unsupported position format
          }
       }
    }
 
    return 0;
 }
 
 STBTT_DEF int  stbtt_GetGlyphKernAdvance(const stbtt_fontinfo *info, int g1, int g2)
 {
    int xAdvance = 0;
 
    if (info->gpos)
       xAdvance += stbtt__GetGlyphGPOSInfoAdvance(info, g1, g2);
    else if (info->kern)
       xAdvance += stbtt__GetGlyphKernInfoAdvance(info, g1, g2);
 
    return xAdvance;
 }
 
 STBTT_DEF void stbtt_GetFontVMetrics(const stbtt_fontinfo *info, int *ascent, int *descent, int *lineGap)
 {
    if (ascent ) *ascent  = ttSHORT(info->data+info->hhea + 4);
    if (descent) *descent = ttSHORT(info->data+info->hhea + 6);
    if (lineGap) *lineGap = ttSHORT(info->data+info->hhea + 8);
 }
 
 STBTT_DEF int  stbtt_GetFontVMetricsOS2(const stbtt_fontinfo *info, int *typoAscent, int *typoDescent, int *typoLineGap)
 {
    int tab = stbtt__find_table(info->data, info->fontstart, "OS/2");
    if (!tab)
       return 0;
    if (typoAscent ) *typoAscent  = ttSHORT(info->data+tab + 68);
    if (typoDescent) *typoDescent = ttSHORT(info->data+tab + 70);
    if (typoLineGap) *typoLineGap = ttSHORT(info->data+tab + 72);
    return 1;
 }
 
 STBTT_DEF void stbtt_GetFontBoundingBox(const stbtt_fontinfo *info, int *x0, int *y0, int *x1, int *y1)
 {
    *x0 = ttSHORT(info->data + info->head + 36);
    *y0 = ttSHORT(info->data + info->head + 38);
    *x1 = ttSHORT(info->data + info->head + 40);
    *y1 = ttSHORT(info->data + info->head + 42);
 }
 
 STBTT_DEF float stbtt_ScaleForPixelHeight(const stbtt_fontinfo *info, float height)
 {
    int fheight = ttSHORT(info->data + info->hhea + 4) - ttSHORT(info->data + info->hhea + 6);
    return (float) height / fheight;
 }
 
 STBTT_DEF float stbtt_ScaleForMappingEmToPixels(const stbtt_fontinfo *info, float pixels)
 {
    int unitsPerEm = ttUSHORT(info->data + info->head + 18);
    return pixels / unitsPerEm;
 }
 
 STBTT_DEF stbtt_uint8 *stbtt_FindSVGDoc(const stbtt_fontinfo *info, int gl)
 {
    int i;
    stbtt_uint8 *data = info->data;
    stbtt_uint8 *svg_doc_list = data + stbtt__get_svg((stbtt_fontinfo *) info);
 
    int numEntries = ttUSHORT(svg_doc_list);
    stbtt_uint8 *svg_docs = svg_doc_list + 2;
 
    for(i=0; i<numEntries; i++) {
       stbtt_uint8 *svg_doc = svg_docs + (12 * i);
       if ((gl >= ttUSHORT(svg_doc)) && (gl <= ttUSHORT(svg_doc + 2)))
          return svg_doc;
    }
    return 0;
 }
 
 STBTT_DEF int stbtt_GetGlyphSVG(const stbtt_fontinfo *info, int gl, const char **svg)
 {
    stbtt_uint8 *data = info->data;
    stbtt_uint8 *svg_doc;
 
    if (info->svg == 0)
       return 0;
 
    svg_doc = stbtt_FindSVGDoc(info, gl);
    if (svg_doc != NULL) {
       *svg = (char *) data + info->svg + ttULONG(svg_doc + 4);
       return ttULONG(svg_doc + 8);
    } else {
       return 0;
    }
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // antialiasing software rasterizer
 //
 
 STBTT_DEF void stbtt_GetGlyphBitmapBoxSubpixel(const stbtt_fontinfo *font, int glyph, float scale_x, float scale_y,float shift_x, float shift_y, int *ix0, int *iy0, int *ix1, int *iy1)
 {
    int x0=0,y0=0,x1,y1; // =0 suppresses compiler warning
    if (!stbtt_GetGlyphBox(font, glyph, &x0,&y0,&x1,&y1)) {
       // e.g. space character
       if (ix0) *ix0 = 0;
       if (iy0) *iy0 = 0;
       if (ix1) *ix1 = 0;
       if (iy1) *iy1 = 0;
    } else {
       // move to integral bboxes (treating pixels as little squares, what pixels get touched)?
       if (ix0) *ix0 = STBTT_ifloor( x0 * scale_x + shift_x);
       if (iy0) *iy0 = STBTT_ifloor(-y1 * scale_y + shift_y);
       if (ix1) *ix1 = STBTT_iceil ( x1 * scale_x + shift_x);
       if (iy1) *iy1 = STBTT_iceil (-y0 * scale_y + shift_y);
    }
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 //  Rasterizer
 
 typedef struct stbtt__hheap_chunk
 {
    struct stbtt__hheap_chunk *next;
 } stbtt__hheap_chunk;
 
 typedef struct stbtt__hheap
 {
    struct stbtt__hheap_chunk *head;
    void   *first_free;
    int    num_remaining_in_head_chunk;
 } stbtt__hheap;
 
 static void *stbtt__hheap_alloc(Arena *a, stbtt__hheap *hh, size_t size)
 {
    if (hh->first_free) {
       void *p = hh->first_free;
       hh->first_free = * (void **) p;
       return p;
    } else {
       if (hh->num_remaining_in_head_chunk == 0) {
          int count = (size < 32 ? 2000 : size < 128 ? 800 : 100);
          stbtt__hheap_chunk *c = alloc_(a, sizeof(stbtt__hheap_chunk) + size * count, _Alignof(stbtt__hheap_chunk), 1);
          c->next = hh->head;
          hh->head = c;
          hh->num_remaining_in_head_chunk = count;
       }
       --hh->num_remaining_in_head_chunk;
       return (char *) (hh->head) + sizeof(stbtt__hheap_chunk) + size * hh->num_remaining_in_head_chunk;
    }
 }
 
 static void stbtt__hheap_free(stbtt__hheap *hh, void *p)
 {
    *(void **) p = hh->first_free;
    hh->first_free = p;
 }
 
 typedef struct stbtt__edge {
    float x0,y0, x1,y1;
    int invert;
 } stbtt__edge;
 
 
 typedef struct stbtt__active_edge
 {
    struct stbtt__active_edge *next;
    #if STBTT_RASTERIZER_VERSION == 2
    float fx,fdx,fdy;
    float direction;
    float sy;
    float ey;
    #else
    #error "Unrecognized value of STBTT_RASTERIZER_VERSION"
    #endif
 } stbtt__active_edge;
 
 #if STBTT_RASTERIZER_VERSION == 2
 static stbtt__active_edge *stbtt__new_active(Arena *a, stbtt__hheap *hh, stbtt__edge *e, int off_x, float start_point)
 {
    stbtt__active_edge *z = (stbtt__active_edge *) stbtt__hheap_alloc(a, hh, sizeof(*z));
    float dxdy = (e->x1 - e->x0) / (e->y1 - e->y0);
    STBTT_assert(z != NULL);
    //STBTT_assert(e->y0 <= start_point);
    if (!z) return z;
    z->fdx = dxdy;
    z->fdy = dxdy != 0.0f ? (1.0f/dxdy) : 0.0f;
    z->fx = e->x0 + dxdy * (start_point - e->y0);
    z->fx -= off_x;
    z->direction = e->invert ? 1.0f : -1.0f;
    z->sy = e->y0;
    z->ey = e->y1;
    z->next = 0;
    return z;
 }
 
 // the edge passed in here does not cross the vertical line at x or the vertical line at x+1
 // (i.e. it has already been clipped to those)
 static void stbtt__handle_clipped_edge(float *scanline, int x, stbtt__active_edge *e, float x0, float y0, float x1, float y1)
 {
    if (y0 == y1) return;
    STBTT_assert(y0 < y1);
    STBTT_assert(e->sy <= e->ey);
    if (y0 > e->ey) return;
    if (y1 < e->sy) return;
    if (y0 < e->sy) {
       x0 += (x1-x0) * (e->sy - y0) / (y1-y0);
       y0 = e->sy;
    }
    if (y1 > e->ey) {
       x1 += (x1-x0) * (e->ey - y1) / (y1-y0);
       y1 = e->ey;
    }
 
    if (x0 == x)
       STBTT_assert(x1 <= x+1);
    else if (x0 == x+1)
       STBTT_assert(x1 >= x);
    else if (x0 <= x)
       STBTT_assert(x1 <= x);
    else if (x0 >= x+1)
       STBTT_assert(x1 >= x+1);
    else
       STBTT_assert(x1 >= x && x1 <= x+1);
 
    if (x0 <= x && x1 <= x)
       scanline[x] += e->direction * (y1-y0);
    else if (x0 >= x+1 && x1 >= x+1)
       ;
    else {
       STBTT_assert(x0 >= x && x0 <= x+1 && x1 >= x && x1 <= x+1);
       scanline[x] += e->direction * (y1-y0) * (1-((x0-x)+(x1-x))/2); // coverage = 1 - average x position
    }
 }
 
 static float stbtt__sized_trapezoid_area(float height, float top_width, float bottom_width)
 {
    STBTT_assert(top_width >= 0);
    STBTT_assert(bottom_width >= 0);
    return (top_width + bottom_width) / 2.0f * height;
 }
 
 static float stbtt__position_trapezoid_area(float height, float tx0, float tx1, float bx0, float bx1)
 {
    return stbtt__sized_trapezoid_area(height, tx1 - tx0, bx1 - bx0);
 }
 
 static float stbtt__sized_triangle_area(float height, float width)
 {
    return height * width / 2;
 }
 
 static void stbtt__fill_active_edges_new(float *scanline, float *scanline_fill, int len, stbtt__active_edge *e, float y_top)
 {
    float y_bottom = y_top+1;
 
    while (e) {
       // brute force every pixel
 
       // compute intersection points with top & bottom
       STBTT_assert(e->ey >= y_top);
 
       if (e->fdx == 0) {
          float x0 = e->fx;
          if (x0 < len) {
             if (x0 >= 0) {
                stbtt__handle_clipped_edge(scanline,(int) x0,e, x0,y_top, x0,y_bottom);
                stbtt__handle_clipped_edge(scanline_fill-1,(int) x0+1,e, x0,y_top, x0,y_bottom);
             } else {
                stbtt__handle_clipped_edge(scanline_fill-1,0,e, x0,y_top, x0,y_bottom);
             }
          }
       } else {
          float x0 = e->fx;
          float dx = e->fdx;
          float xb = x0 + dx;
          float x_top, x_bottom;
          float sy0,sy1;
          float dy = e->fdy;
          STBTT_assert(e->sy <= y_bottom && e->ey >= y_top);
 
          // compute endpoints of line segment clipped to this scanline (if the
          // line segment starts on this scanline. x0 is the intersection of the
          // line with y_top, but that may be off the line segment.
          if (e->sy > y_top) {
             x_top = x0 + dx * (e->sy - y_top);
             sy0 = e->sy;
          } else {
             x_top = x0;
             sy0 = y_top;
          }
          if (e->ey < y_bottom) {
             x_bottom = x0 + dx * (e->ey - y_top);
             sy1 = e->ey;
          } else {
             x_bottom = xb;
             sy1 = y_bottom;
          }
 
          if (x_top >= 0 && x_bottom >= 0 && x_top < len && x_bottom < len) {
             // from here on, we don't have to range check x values
 
             if ((int) x_top == (int) x_bottom) {
                float height;
                // simple case, only spans one pixel
                int x = (int) x_top;
                height = (sy1 - sy0) * e->direction;
                STBTT_assert(x >= 0 && x < len);
                scanline[x]      += stbtt__position_trapezoid_area(height, x_top, x+1.0f, x_bottom, x+1.0f);
                scanline_fill[x] += height; // everything right of this pixel is filled
             } else {
                int x,x1,x2;
                float y_crossing, y_final, step, sign, area;
                // covers 2+ pixels
                if (x_top > x_bottom) {
                   // flip scanline vertically; signed area is the same
                   float t;
                   sy0 = y_bottom - (sy0 - y_top);
                   sy1 = y_bottom - (sy1 - y_top);
                   t = sy0, sy0 = sy1, sy1 = t;
                   t = x_bottom, x_bottom = x_top, x_top = t;
                   dx = -dx;
                   dy = -dy;
                   t = x0, x0 = xb, xb = t;
                }
                STBTT_assert(dy >= 0);
                STBTT_assert(dx >= 0);
 
                x1 = (int) x_top;
                x2 = (int) x_bottom;
                // compute intersection with y axis at x1+1
                y_crossing = y_top + dy * (x1+1 - x0);
 
                // compute intersection with y axis at x2
                y_final = y_top + dy * (x2 - x0);
 
                //           x1    x_top                            x2    x_bottom
                //     y_top  +------|-----+------------+------------+--------|---+------------+
                //            |            |            |            |            |            |
                //            |            |            |            |            |            |
                //       sy0  |      Txxxxx|............|............|............|............|
                // y_crossing |            *xxxxx.......|............|............|............|
                //            |            |     xxxxx..|............|............|............|
                //            |            |     /-   xx*xxxx........|............|............|
                //            |            | dy <       |    xxxxxx..|............|............|
                //   y_final  |            |     \-     |          xx*xxx.........|............|
                //       sy1  |            |            |            |   xxxxxB...|............|
                //            |            |            |            |            |            |
                //            |            |            |            |            |            |
                //  y_bottom  +------------+------------+------------+------------+------------+
                //
                // goal is to measure the area covered by '.' in each pixel
 
                // if x2 is right at the right edge of x1, y_crossing can blow up, github #1057
                // @TODO: maybe test against sy1 rather than y_bottom?
                if (y_crossing > y_bottom)
                   y_crossing = y_bottom;
 
                sign = e->direction;
 
                // area of the rectangle covered from sy0..y_crossing
                area = sign * (y_crossing-sy0);
 
                // area of the triangle (x_top,sy0), (x1+1,sy0), (x1+1,y_crossing)
                scanline[x1] += stbtt__sized_triangle_area(area, x1+1 - x_top);
 
                // check if final y_crossing is blown up; no test case for this
                if (y_final > y_bottom) {
                   y_final = y_bottom;
                   dy = (y_final - y_crossing ) / (x2 - (x1+1)); // if denom=0, y_final = y_crossing, so y_final <= y_bottom
                }
 
                // in second pixel, area covered by line segment found in first pixel
                // is always a rectangle 1 wide * the height of that line segment; this
                // is exactly what the variable 'area' stores. it also gets a contribution
                // from the line segment within it. the THIRD pixel will get the first
                // pixel's rectangle contribution, the second pixel's rectangle contribution,
                // and its own contribution. the 'own contribution' is the same in every pixel except
                // the leftmost and rightmost, a trapezoid that slides down in each pixel.
                // the second pixel's contribution to the third pixel will be the
                // rectangle 1 wide times the height change in the second pixel, which is dy.
 
                step = sign * dy * 1; // dy is dy/dx, change in y for every 1 change in x,
                // which multiplied by 1-pixel-width is how much pixel area changes for each step in x
                // so the area advances by 'step' every time
 
                for (x = x1+1; x < x2; ++x) {
                   scanline[x] += area + step/2; // area of trapezoid is 1*step/2
                   area += step;
                }
                STBTT_assert(STBTT_fabs(area) <= 1.01f); // accumulated error from area += step unless we round step down
                STBTT_assert(sy1 > y_final-0.01f);
 
                // area covered in the last pixel is the rectangle from all the pixels to the left,
                // plus the trapezoid filled by the line segment in this pixel all the way to the right edge
                scanline[x2] += area + sign * stbtt__position_trapezoid_area(sy1-y_final, (float) x2, x2+1.0f, x_bottom, x2+1.0f);
 
                // the rest of the line is filled based on the total height of the line segment in this pixel
                scanline_fill[x2] += sign * (sy1-sy0);
             }
          } else {
             // if edge goes outside of box we're drawing, we require
             // clipping logic. since this does not match the intended use
             // of this library, we use a different, very slow brute
             // force implementation
             // note though that this does happen some of the time because
             // x_top and x_bottom can be extrapolated at the top & bottom of
             // the shape and actually lie outside the bounding box
             int x;
             for (x=0; x < len; ++x) {
                // cases:
                //
                // there can be up to two intersections with the pixel. any intersection
                // with left or right edges can be handled by splitting into two (or three)
                // regions. intersections with top & bottom do not necessitate case-wise logic.
                //
                // the old way of doing this found the intersections with the left & right edges,
                // then used some simple logic to produce up to three segments in sorted order
                // from top-to-bottom. however, this had a problem: if an x edge was epsilon
                // across the x border, then the corresponding y position might not be distinct
                // from the other y segment, and it might ignored as an empty segment. to avoid
                // that, we need to explicitly produce segments based on x positions.
 
                // rename variables to clearly-defined pairs
                float y0 = y_top;
                float x1 = (float) (x);
                float x2 = (float) (x+1);
                float x3 = xb;
                float y3 = y_bottom;
 
                // x = e->x + e->dx * (y-y_top)
                // (y-y_top) = (x - e->x) / e->dx
                // y = (x - e->x) / e->dx + y_top
                float y1 = (x - x0) / dx + y_top;
                float y2 = (x+1 - x0) / dx + y_top;
 
                if (x0 < x1 && x3 > x2) {         // three segments descending down-right
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
                   stbtt__handle_clipped_edge(scanline,x,e, x1,y1, x2,y2);
                   stbtt__handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
                } else if (x3 < x1 && x0 > x2) {  // three segments descending down-left
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
                   stbtt__handle_clipped_edge(scanline,x,e, x2,y2, x1,y1);
                   stbtt__handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
                } else if (x0 < x1 && x3 > x1) {  // two segments across x, down-right
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
                   stbtt__handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
                } else if (x3 < x1 && x0 > x1) {  // two segments across x, down-left
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
                   stbtt__handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
                } else if (x0 < x2 && x3 > x2) {  // two segments across x+1, down-right
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
                   stbtt__handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
                } else if (x3 < x2 && x0 > x2) {  // two segments across x+1, down-left
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
                   stbtt__handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
                } else {  // one segment
                   stbtt__handle_clipped_edge(scanline,x,e, x0,y0, x3,y3);
                }
             }
          }
       }
       e = e->next;
    }
 }
 
 // directly AA rasterize edges w/o supersampling
 static void stbtt__rasterize_sorted_edges(Arena *a, stbtt__bitmap *result, stbtt__edge *e, int n, int vsubsample, int off_x, int off_y)
 {
    stbtt__hheap hh = { 0, 0, 0 };
    stbtt__active_edge *active = NULL;
    int y,j=0, i;
    float scanline_data[129], *scanline, *scanline2;
 
    STBTT__NOTUSED(vsubsample);
 
    if (result->w > 64) scanline = alloc(a, float, result->w * 2 + 1);
    else                scanline = scanline_data;
 
    scanline2 = scanline + result->w;
 
    y = off_y;
    e[n].y0 = (float) (off_y + result->h) + 1;
 
    while (j < result->h) {
       // find center of pixel for this scanline
       float scan_y_top    = y + 0.0f;
       float scan_y_bottom = y + 1.0f;
       stbtt__active_edge **step = &active;
 
       mem_clear(scanline , 0, result->w*sizeof(scanline[0]));
       mem_clear(scanline2, 0, (result->w+1)*sizeof(scanline[0]));
 
       // update all active edges;
       // remove all active edges that terminate before the top of this scanline
       while (*step) {
          stbtt__active_edge * z = *step;
          if (z->ey <= scan_y_top) {
             *step = z->next; // delete from list
             STBTT_assert(z->direction);
             z->direction = 0;
             stbtt__hheap_free(&hh, z);
          } else {
             step = &((*step)->next); // advance through list
          }
       }
 
       // insert all edges that start before the bottom of this scanline
       while (e->y0 <= scan_y_bottom) {
          if (e->y0 != e->y1) {
             stbtt__active_edge *z = stbtt__new_active(a, &hh, e, off_x, scan_y_top);
             if (z != NULL) {
                if (j == 0 && off_y != 0) {
                   if (z->ey < scan_y_top) {
                      // this can happen due to subpixel positioning and some kind of fp rounding error i think
                      z->ey = scan_y_top;
                   }
                }
                STBTT_assert(z->ey >= scan_y_top); // if we get really unlucky a tiny bit of an edge can be out of bounds
                // insert at front
                z->next = active;
                active = z;
             }
          }
          ++e;
       }
 
       // now process all active edges
       if (active)
          stbtt__fill_active_edges_new(scanline, scanline2+1, result->w, active, scan_y_top);
 
       {
          float sum = 0;
          for (i=0; i < result->w; ++i) {
             float k;
             int m;
             sum += scanline2[i];
             k = scanline[i] + sum;
             k = (float) STBTT_fabs(k)*255 + 0.5f;
             m = (int) k;
             if (m > 255) m = 255;
             result->pixels[j*result->stride + i] = (unsigned char) m;
          }
       }
       // advance all the edges
       step = &active;
       while (*step) {
          stbtt__active_edge *z = *step;
          z->fx += z->fdx; // advance to position for current scanline
          step = &((*step)->next); // advance through list
       }
 
       ++y;
       ++j;
    }
 }
 #else
 #error "Unrecognized value of STBTT_RASTERIZER_VERSION"
 #endif
 
 #define STBTT__COMPARE(a,b)  ((a)->y0 < (b)->y0)
 
 static void stbtt__sort_edges_ins_sort(stbtt__edge *p, int n)
 {
    int i,j;
    for (i=1; i < n; ++i) {
       stbtt__edge t = p[i], *a = &t;
       j = i;
       while (j > 0) {
          stbtt__edge *b = &p[j-1];
          int c = STBTT__COMPARE(a,b);
          if (!c) break;
          p[j] = p[j-1];
          --j;
       }
       if (i != j)
          p[j] = t;
    }
 }
 
 static void stbtt__sort_edges_quicksort(stbtt__edge *p, int n)
 {
    /* threshold for transitioning to insertion sort */
    while (n > 12) {
       stbtt__edge t;
       int c01,c12,c,m,i,j;
 
       /* compute median of three */
       m = n >> 1;
       c01 = STBTT__COMPARE(&p[0],&p[m]);
       c12 = STBTT__COMPARE(&p[m],&p[n-1]);
       /* if 0 >= mid >= end, or 0 < mid < end, then use mid */
       if (c01 != c12) {
          /* otherwise, we'll need to swap something else to middle */
          int z;
          c = STBTT__COMPARE(&p[0],&p[n-1]);
          /* 0>mid && mid<n:  0>n => n; 0<n => 0 */
          /* 0<mid && mid>n:  0>n => 0; 0<n => n */
          z = (c == c12) ? 0 : n-1;
          t = p[z];
          p[z] = p[m];
          p[m] = t;
       }
       /* now p[m] is the median-of-three */
       /* swap it to the beginning so it won't move around */
       t = p[0];
       p[0] = p[m];
       p[m] = t;
 
       /* partition loop */
       i=1;
       j=n-1;
       for(;;) {
          /* handling of equality is crucial here */
          /* for sentinels & efficiency with duplicates */
          for (;;++i) {
             if (!STBTT__COMPARE(&p[i], &p[0])) break;
          }
          for (;;--j) {
             if (!STBTT__COMPARE(&p[0], &p[j])) break;
          }
          /* make sure we haven't crossed */
          if (i >= j) break;
          t = p[i];
          p[i] = p[j];
          p[j] = t;
 
          ++i;
          --j;
       }
       /* recurse on smaller side, iterate on larger */
       if (j < (n-i)) {
          stbtt__sort_edges_quicksort(p,j);
          p = p+i;
          n = n-i;
       } else {
          stbtt__sort_edges_quicksort(p+i, n-i);
          n = j;
       }
    }
 }
 
 static void stbtt__sort_edges(stbtt__edge *p, int n)
 {
    stbtt__sort_edges_quicksort(p, n);
    stbtt__sort_edges_ins_sort(p, n);
 }
 
 typedef v2 stbtt__point;
 
 static void stbtt__rasterize(Arena *a, stbtt__bitmap *result, stbtt__point *pts, int *wcount, int windings, float scale_x, float scale_y, float shift_x, float shift_y, int off_x, int off_y, int invert)
 {
    float y_scale_inv = invert ? -scale_y : scale_y;
    stbtt__edge *e;
    int n,i,j,k,m;
 #if STBTT_RASTERIZER_VERSION == 2
    int vsubsample = 1;
 #else
    #error "Unrecognized value of STBTT_RASTERIZER_VERSION"
 #endif
    // vsubsample should divide 255 evenly; otherwise we won't reach full opacity
 
    // now we have to blow out the windings into explicit edge lists
    n = 0;
    for (i=0; i < windings; ++i)
       n += wcount[i];
 
    e = alloc(a, typeof(*e), n + 1); // add an extra one as a sentinel
    n = 0;
 
    m=0;
    for (i=0; i < windings; ++i) {
       stbtt__point *p = pts + m;
       m += wcount[i];
       j = wcount[i]-1;
       for (k=0; k < wcount[i]; j=k++) {
          int a=k,b=j;
          // skip the edge if horizontal
          if (p[j].y == p[k].y)
             continue;
          // add edge from j to k to the list
          e[n].invert = 0;
          if (invert ? p[j].y > p[k].y : p[j].y < p[k].y) {
             e[n].invert = 1;
             a=j,b=k;
          }
          e[n].x0 = p[a].x * scale_x + shift_x;
          e[n].y0 = (p[a].y * y_scale_inv + shift_y) * vsubsample;
          e[n].x1 = p[b].x * scale_x + shift_x;
          e[n].y1 = (p[b].y * y_scale_inv + shift_y) * vsubsample;
          ++n;
       }
    }
 
    // now sort the edges by their highest point (should snap to integer, and then by x)
    //STBTT_sort(e, n, sizeof(e[0]), stbtt__edge_compare);
    stbtt__sort_edges(e, n);
 
    // now, traverse the scanlines and find the intersections on each scanline, use xor winding rule
    stbtt__rasterize_sorted_edges(a, result, e, n, vsubsample, off_x, off_y);
 }
 
 static void stbtt__add_point(stbtt__point *points, int n, float x, float y)
 {
    if (!points) return; // during first pass, it's unallocated
    points[n].x = x;
    points[n].y = y;
 }
 
 // tessellate until threshold p is happy... @TODO warped to compensate for non-linear stretching
 static int stbtt__tesselate_curve(stbtt__point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float objspace_flatness_squared, int n)
 {
    // midpoint
    float mx = (x0 + 2*x1 + x2)/4;
    float my = (y0 + 2*y1 + y2)/4;
    // versus directly drawn line
    float dx = (x0+x2)/2 - mx;
    float dy = (y0+y2)/2 - my;
    if (n > 16) // 65536 segments on one curve better be enough!
       return 1;
    if (dx*dx+dy*dy > objspace_flatness_squared) { // half-pixel error allowed... need to be smaller if AA
       stbtt__tesselate_curve(points, num_points, x0,y0, (x0+x1)/2.0f,(y0+y1)/2.0f, mx,my, objspace_flatness_squared,n+1);
       stbtt__tesselate_curve(points, num_points, mx,my, (x1+x2)/2.0f,(y1+y2)/2.0f, x2,y2, objspace_flatness_squared,n+1);
    } else {
       stbtt__add_point(points, *num_points,x2,y2);
       *num_points = *num_points+1;
    }
    return 1;
 }
 
 static void stbtt__tesselate_cubic(stbtt__point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3, float objspace_flatness_squared, int n)
 {
    // @TODO this "flatness" calculation is just made-up nonsense that seems to work well enough
    float dx0 = x1-x0;
    float dy0 = y1-y0;
    float dx1 = x2-x1;
    float dy1 = y2-y1;
    float dx2 = x3-x2;
    float dy2 = y3-y2;
    float dx = x3-x0;
    float dy = y3-y0;
    float longlen = (float) (STBTT_sqrt(dx0*dx0+dy0*dy0)+STBTT_sqrt(dx1*dx1+dy1*dy1)+STBTT_sqrt(dx2*dx2+dy2*dy2));
    float shortlen = (float) STBTT_sqrt(dx*dx+dy*dy);
    float flatness_squared = longlen*longlen-shortlen*shortlen;
 
    if (n > 16) // 65536 segments on one curve better be enough!
       return;
 
    if (flatness_squared > objspace_flatness_squared) {
       float x01 = (x0+x1)/2;
       float y01 = (y0+y1)/2;
       float x12 = (x1+x2)/2;
       float y12 = (y1+y2)/2;
       float x23 = (x2+x3)/2;
       float y23 = (y2+y3)/2;
 
       float xa = (x01+x12)/2;
       float ya = (y01+y12)/2;
       float xb = (x12+x23)/2;
       float yb = (y12+y23)/2;
 
       float mx = (xa+xb)/2;
       float my = (ya+yb)/2;
 
       stbtt__tesselate_cubic(points, num_points, x0,y0, x01,y01, xa,ya, mx,my, objspace_flatness_squared,n+1);
       stbtt__tesselate_cubic(points, num_points, mx,my, xb,yb, x23,y23, x3,y3, objspace_flatness_squared,n+1);
    } else {
       stbtt__add_point(points, *num_points,x3,y3);
       *num_points = *num_points+1;
    }
 }
 
 // returns number of contours
 static stbtt__point *stbtt_FlattenCurves(Arena *a, stbtt_vertex *vertices, int num_verts, float objspace_flatness, int **contour_lengths, int *num_contours)
 {
    stbtt__point *points=0;
    int num_points=0;
 
    float objspace_flatness_squared = objspace_flatness * objspace_flatness;
    int i,n=0,start=0, pass;
 
    // count how many "moves" there are to get the contour count
    for (i=0; i < num_verts; ++i)
       if (vertices[i].type == STBTT_vmove)
          ++n;
 
    *num_contours = n;
    if (n == 0) return 0;
 
    *contour_lengths = alloc(a, typeof(**contour_lengths), n);
 
    // make two passes through the points so we don't need to realloc
    for (pass=0; pass < 2; ++pass) {
       float x=0,y=0;
       if (pass == 1) {
          points = alloc(a, typeof(*points), num_points);
       }
       num_points = 0;
       n= -1;
       for (i=0; i < num_verts; ++i) {
          switch (vertices[i].type) {
             case STBTT_vmove:
                // start the next contour
                if (n >= 0)
                   (*contour_lengths)[n] = num_points - start;
                ++n;
                start = num_points;
 
                x = vertices[i].x, y = vertices[i].y;
                stbtt__add_point(points, num_points++, x,y);
                break;
             case STBTT_vline:
                x = vertices[i].x, y = vertices[i].y;
                stbtt__add_point(points, num_points++, x, y);
                break;
             case STBTT_vcurve:
                stbtt__tesselate_curve(points, &num_points, x,y,
                                         vertices[i].cx, vertices[i].cy,
                                         vertices[i].x,  vertices[i].y,
                                         objspace_flatness_squared, 0);
                x = vertices[i].x, y = vertices[i].y;
                break;
             case STBTT_vcubic:
                stbtt__tesselate_cubic(points, &num_points, x,y,
                                         vertices[i].cx, vertices[i].cy,
                                         vertices[i].cx1, vertices[i].cy1,
                                         vertices[i].x,  vertices[i].y,
                                         objspace_flatness_squared, 0);
                x = vertices[i].x, y = vertices[i].y;
                break;
          }
       }
       (*contour_lengths)[n] = num_points - start;
    }
 
    return points;
 }
 
 STBTT_DEF void stbtt_Rasterize(Arena a, stbtt__bitmap *result, float flatness_in_pixels, stbtt_vertex *vertices, int num_verts, float scale_x, float scale_y, float shift_x, float shift_y, int x_off, int y_off, int invert)
 {
    float scale            = scale_x > scale_y ? scale_y : scale_x;
    int winding_count      = 0;
    int *winding_lengths   = NULL;
    stbtt__point *windings = stbtt_FlattenCurves(&a, vertices, num_verts, flatness_in_pixels / scale, &winding_lengths, &winding_count);
    if (windings)
       stbtt__rasterize(&a, result, windings, winding_lengths, winding_count, scale_x, scale_y, shift_x, shift_y, x_off, y_off, invert);
 }
 
 STBTT_DEF void stbtt_MakeGlyphBitmapSubpixel(Arena a, const stbtt_fontinfo *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int glyph)
 {
    int ix0,iy0;
    stbtt_vertex *vertices;
    int num_verts = stbtt_GetGlyphShape(&a, info, glyph, &vertices);
    stbtt__bitmap gbm;
 
    stbtt_GetGlyphBitmapBoxSubpixel(info, glyph, scale_x, scale_y, shift_x, shift_y, &ix0,&iy0,0,0);
    gbm.pixels = output;
    gbm.w = out_w;
    gbm.h = out_h;
    gbm.stride = out_stride;
 
    if (gbm.w && gbm.h)
       stbtt_Rasterize(a, &gbm, 0.35f, vertices, num_verts, scale_x, scale_y, shift_x, shift_y, ix0,iy0, 1);
 }
 
 STBTT_DEF void stbtt_MakeGlyphBitmap(Arena a, const stbtt_fontinfo *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, int glyph)
 {
 	stbtt_MakeGlyphBitmapSubpixel(a, info, output, out_w, out_h, out_stride, scale_x, scale_y, 0.0f,0.0f, glyph);
 }
 
 #define STBTT__OVER_MASK  (STBTT_MAX_OVERSAMPLE-1)
 
 static void stbtt__h_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
 {
    unsigned char buffer[STBTT_MAX_OVERSAMPLE] = {0};
    int safe_w = w - kernel_width;
    int j;
    for (j=0; j < h; ++j) {
       int i;
       unsigned int total;
       mem_clear(buffer, 0, kernel_width);
 
       total = 0;
 
       // make kernel_width a constant in common cases so compiler can optimize out the divide
       switch (kernel_width) {
          case 2:
             for (i=0; i <= safe_w; ++i) {
                total += pixels[i] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i];
                pixels[i] = (unsigned char) (total / 2);
             }
             break;
          case 3:
             for (i=0; i <= safe_w; ++i) {
                total += pixels[i] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i];
                pixels[i] = (unsigned char) (total / 3);
             }
             break;
          case 4:
             for (i=0; i <= safe_w; ++i) {
                total += pixels[i] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i];
                pixels[i] = (unsigned char) (total / 4);
             }
             break;
          case 5:
             for (i=0; i <= safe_w; ++i) {
                total += pixels[i] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i];
                pixels[i] = (unsigned char) (total / 5);
             }
             break;
          default:
             for (i=0; i <= safe_w; ++i) {
                total += pixels[i] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i];
                pixels[i] = (unsigned char) (total / kernel_width);
             }
             break;
       }
 
       for (; i < w; ++i) {
          STBTT_assert(pixels[i] == 0);
          total -= buffer[i & STBTT__OVER_MASK];
          pixels[i] = (unsigned char) (total / kernel_width);
       }
 
       pixels += stride_in_bytes;
    }
 }
 
 static void stbtt__v_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
 {
    unsigned char buffer[STBTT_MAX_OVERSAMPLE] = {0};
    int safe_h = h - kernel_width;
    int j;
    for (j=0; j < w; ++j) {
       int i;
       unsigned int total;
       mem_clear(buffer, 0, kernel_width);
 
       total = 0;
 
       // make kernel_width a constant in common cases so compiler can optimize out the divide
       switch (kernel_width) {
          case 2:
             for (i=0; i <= safe_h; ++i) {
                total += pixels[i*stride_in_bytes] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i*stride_in_bytes];
                pixels[i*stride_in_bytes] = (unsigned char) (total / 2);
             }
             break;
          case 3:
             for (i=0; i <= safe_h; ++i) {
                total += pixels[i*stride_in_bytes] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i*stride_in_bytes];
                pixels[i*stride_in_bytes] = (unsigned char) (total / 3);
             }
             break;
          case 4:
             for (i=0; i <= safe_h; ++i) {
                total += pixels[i*stride_in_bytes] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i*stride_in_bytes];
                pixels[i*stride_in_bytes] = (unsigned char) (total / 4);
             }
             break;
          case 5:
             for (i=0; i <= safe_h; ++i) {
                total += pixels[i*stride_in_bytes] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i*stride_in_bytes];
                pixels[i*stride_in_bytes] = (unsigned char) (total / 5);
             }
             break;
          default:
             for (i=0; i <= safe_h; ++i) {
                total += pixels[i*stride_in_bytes] - buffer[i & STBTT__OVER_MASK];
                buffer[(i+kernel_width) & STBTT__OVER_MASK] = pixels[i*stride_in_bytes];
                pixels[i*stride_in_bytes] = (unsigned char) (total / kernel_width);
             }
             break;
       }
 
       for (; i < h; ++i) {
          STBTT_assert(pixels[i*stride_in_bytes] == 0);
          total -= buffer[i & STBTT__OVER_MASK];
          pixels[i*stride_in_bytes] = (unsigned char) (total / kernel_width);
       }
 
       pixels += 1;
    }
 }
 
 static float stbtt__oversample_shift(int oversample)
 {
    if (!oversample)
       return 0.0f;
 
    // The prefilter is a box filter of width "oversample",
    // which shifts phase by (oversample - 1)/2 pixels in
    // oversampled space. We want to shift in the opposite
    // direction to counter this.
    return (float)-(oversample - 1) / (2.0f * (float)oversample);
 }
 
 STBTT_DEF void stbtt_MakeGlyphBitmapSubpixelPrefilter(Arena a, const stbtt_fontinfo *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int prefilter_x, int prefilter_y, float *sub_x, float *sub_y, int glyph)
 {
    stbtt_MakeGlyphBitmapSubpixel(a, info,
                                  output,
                                  out_w - (prefilter_x - 1),
                                  out_h - (prefilter_y - 1),
                                  out_stride,
                                  scale_x,
                                  scale_y,
                                  shift_x,
                                  shift_y,
                                  glyph);
 
    if (prefilter_x > 1)
       stbtt__h_prefilter(output, out_w, out_h, out_stride, prefilter_x);
 
    if (prefilter_y > 1)
       stbtt__v_prefilter(output, out_w, out_h, out_stride, prefilter_y);
 
    *sub_x = stbtt__oversample_shift(prefilter_x);
    *sub_y = stbtt__oversample_shift(prefilter_y);
 }
 
 STBTT_DEF void stbtt_GetScaledFontVMetrics(unsigned char *fontdata, int index, float size, float *ascent, float *descent, float *lineGap)
 {
    int i_ascent, i_descent, i_lineGap;
    float scale;
    stbtt_fontinfo info;
    stbtt_InitFont(&info, fontdata, stbtt_GetFontOffsetForIndex(fontdata, index));
    scale = size > 0 ? stbtt_ScaleForPixelHeight(&info, size) : stbtt_ScaleForMappingEmToPixels(&info, -size);
    stbtt_GetFontVMetrics(&info, &i_ascent, &i_descent, &i_lineGap);
    *ascent  = (float) i_ascent  * scale;
    *descent = (float) i_descent * scale;
    *lineGap = (float) i_lineGap * scale;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // sdf computation
 //
 
 #define STBTT_min(a,b)  ((a) < (b) ? (a) : (b))
 #define STBTT_max(a,b)  ((a) < (b) ? (b) : (a))
 
 static int stbtt__ray_intersect_bezier(float orig[2], float ray[2], float q0[2], float q1[2], float q2[2], float hits[2][2])
 {
    float q0perp = q0[1]*ray[0] - q0[0]*ray[1];
    float q1perp = q1[1]*ray[0] - q1[0]*ray[1];
    float q2perp = q2[1]*ray[0] - q2[0]*ray[1];
    float roperp = orig[1]*ray[0] - orig[0]*ray[1];
 
    float a = q0perp - 2*q1perp + q2perp;
    float b = q1perp - q0perp;
    float c = q0perp - roperp;
 
    float s0 = 0., s1 = 0.;
    int num_s = 0;
 
    if (a != 0.0) {
       float discr = b*b - a*c;
       if (discr > 0.0) {
          float rcpna = -1 / a;
          float d = (float) STBTT_sqrt(discr);
          s0 = (b+d) * rcpna;
          s1 = (b-d) * rcpna;
          if (s0 >= 0.0 && s0 <= 1.0)
             num_s = 1;
          if (d > 0.0 && s1 >= 0.0 && s1 <= 1.0) {
             if (num_s == 0) s0 = s1;
             ++num_s;
          }
       }
    } else {
       // 2*b*s + c = 0
       // s = -c / (2*b)
       s0 = c / (-2 * b);
       if (s0 >= 0.0 && s0 <= 1.0)
          num_s = 1;
    }
 
    if (num_s == 0)
       return 0;
    else {
       float rcp_len2 = 1 / (ray[0]*ray[0] + ray[1]*ray[1]);
       float rayn_x = ray[0] * rcp_len2, rayn_y = ray[1] * rcp_len2;
 
       float q0d =   q0[0]*rayn_x +   q0[1]*rayn_y;
       float q1d =   q1[0]*rayn_x +   q1[1]*rayn_y;
       float q2d =   q2[0]*rayn_x +   q2[1]*rayn_y;
       float rod = orig[0]*rayn_x + orig[1]*rayn_y;
 
       float q10d = q1d - q0d;
       float q20d = q2d - q0d;
       float q0rd = q0d - rod;
 
       hits[0][0] = q0rd + s0*(2.0f - 2.0f*s0)*q10d + s0*s0*q20d;
       hits[0][1] = a*s0+b;
 
       if (num_s > 1) {
          hits[1][0] = q0rd + s1*(2.0f - 2.0f*s1)*q10d + s1*s1*q20d;
          hits[1][1] = a*s1+b;
          return 2;
       } else {
          return 1;
       }
    }
 }
 
 static int equal(float *a, float *b)
 {
    return (a[0] == b[0] && a[1] == b[1]);
 }
 
 static int stbtt__compute_crossings_x(float x, float y, int nverts, stbtt_vertex *verts)
 {
    int i;
    float orig[2], ray[2] = { 1, 0 };
    float y_frac;
    int winding = 0;
 
    // make sure y never passes through a vertex of the shape
    y_frac = (float) STBTT_fmod(y, 1.0f);
    if (y_frac < 0.01f)
       y += 0.01f;
    else if (y_frac > 0.99f)
       y -= 0.01f;
 
    orig[0] = x;
    orig[1] = y;
 
    // test a ray from (-infinity,y) to (x,y)
    for (i=0; i < nverts; ++i) {
       if (verts[i].type == STBTT_vline) {
          int x0 = (int) verts[i-1].x, y0 = (int) verts[i-1].y;
          int x1 = (int) verts[i  ].x, y1 = (int) verts[i  ].y;
          if (y > STBTT_min(y0,y1) && y < STBTT_max(y0,y1) && x > STBTT_min(x0,x1)) {
             float x_inter = (y - y0) / (y1 - y0) * (x1-x0) + x0;
             if (x_inter < x)
                winding += (y0 < y1) ? 1 : -1;
          }
       }
       if (verts[i].type == STBTT_vcurve) {
          int x0 = (int) verts[i-1].x , y0 = (int) verts[i-1].y ;
          int x1 = (int) verts[i  ].cx, y1 = (int) verts[i  ].cy;
          int x2 = (int) verts[i  ].x , y2 = (int) verts[i  ].y ;
          int ax = STBTT_min(x0,STBTT_min(x1,x2)), ay = STBTT_min(y0,STBTT_min(y1,y2));
          int by = STBTT_max(y0,STBTT_max(y1,y2));
          if (y > ay && y < by && x > ax) {
             float q0[2],q1[2],q2[2];
             float hits[2][2];
             q0[0] = (float)x0;
             q0[1] = (float)y0;
             q1[0] = (float)x1;
             q1[1] = (float)y1;
             q2[0] = (float)x2;
             q2[1] = (float)y2;
             if (equal(q0,q1) || equal(q1,q2)) {
                x0 = (int)verts[i-1].x;
                y0 = (int)verts[i-1].y;
                x1 = (int)verts[i  ].x;
                y1 = (int)verts[i  ].y;
                if (y > STBTT_min(y0,y1) && y < STBTT_max(y0,y1) && x > STBTT_min(x0,x1)) {
                   float x_inter = (y - y0) / (y1 - y0) * (x1-x0) + x0;
                   if (x_inter < x)
                      winding += (y0 < y1) ? 1 : -1;
                }
             } else {
                int num_hits = stbtt__ray_intersect_bezier(orig, ray, q0, q1, q2, hits);
                if (num_hits >= 1)
                   if (hits[0][0] < 0)
                      winding += (hits[0][1] < 0 ? -1 : 1);
                if (num_hits >= 2)
                   if (hits[1][0] < 0)
                      winding += (hits[1][1] < 0 ? -1 : 1);
             }
          }
       }
    }
    return winding;
 }
 
 static float stbtt__cuberoot( float x )
 {
    if (x<0)
       return -(float) STBTT_pow(-x,1.0f/3.0f);
    else
       return  (float) STBTT_pow( x,1.0f/3.0f);
 }
 
 // x^3 + a*x^2 + b*x + c = 0
 static int stbtt__solve_cubic(float a, float b, float c, float* r)
 {
    float s = -a / 3;
    float p = b - a*a / 3;
    float q = a * (2*a*a - 9*b) / 27 + c;
    float p3 = p*p*p;
    float d = q*q + 4*p3 / 27;
    if (d >= 0) {
       float z = (float) STBTT_sqrt(d);
       float u = (-q + z) / 2;
       float v = (-q - z) / 2;
       u = stbtt__cuberoot(u);
       v = stbtt__cuberoot(v);
       r[0] = s + u + v;
       return 1;
    } else {
       float u = (float) STBTT_sqrt(-p/3);
       float v = (float) STBTT_acos(-STBTT_sqrt(-27/p3) * q / 2) / 3; // p3 must be negative, since d is negative
       float m = (float) STBTT_cos(v);
       float n = (float) STBTT_cos(v-3.141592/2)*1.732050808f;
       r[0] = s + u * 2 * m;
       r[1] = s - u * (m + n);
       r[2] = s - u * (m - n);
 
       //STBTT_assert( STBTT_fabs(((r[0]+a)*r[0]+b)*r[0]+c) < 0.05f);  // these asserts may not be safe at all scales, though they're in bezier t parameter units so maybe?
       //STBTT_assert( STBTT_fabs(((r[1]+a)*r[1]+b)*r[1]+c) < 0.05f);
       //STBTT_assert( STBTT_fabs(((r[2]+a)*r[2]+b)*r[2]+c) < 0.05f);
       return 3;
    }
 }
 
 STBTT_DEF unsigned char *stbtt_GetGlyphSDF(Arena *a, const stbtt_fontinfo *info, float scale, int glyph, int padding, unsigned char onedge_value, float pixel_dist_scale, int *width, int *height, int *xoff, int *yoff)
 {
    float scale_x = scale, scale_y = scale;
    int ix0,iy0,ix1,iy1;
    int w,h;
    unsigned char *data;
 
    if (scale == 0) return NULL;
 
    stbtt_GetGlyphBitmapBoxSubpixel(info, glyph, scale, scale, 0.0f,0.0f, &ix0,&iy0,&ix1,&iy1);
 
    // if empty, return NULL
    if (ix0 == ix1 || iy0 == iy1)
       return NULL;
 
    ix0 -= padding;
    iy0 -= padding;
    ix1 += padding;
    iy1 += padding;
 
    w = (ix1 - ix0);
    h = (iy1 - iy0);
 
    if (width ) *width  = w;
    if (height) *height = h;
    if (xoff  ) *xoff   = ix0;
    if (yoff  ) *yoff   = iy0;
 
    // invert for y-downwards bitmaps
    scale_y = -scale_y;
 
    {
       // distance from singular values (in the same units as the pixel grid)
       const float eps = 1./1024, eps2 = eps*eps;
       int x,y,i,j;
       float *precompute;
       stbtt_vertex *verts;
       int num_verts = stbtt_GetGlyphShape(a, info, glyph, &verts);
       data          = alloc(a, unsigned char, w * h);
       precompute    = alloc(a, float, num_verts);
 
       for (i=0,j=num_verts-1; i < num_verts; j=i++) {
          if (verts[i].type == STBTT_vline) {
             float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
             float x1 = verts[j].x*scale_x, y1 = verts[j].y*scale_y;
             float dist = (float) STBTT_sqrt((x1-x0)*(x1-x0) + (y1-y0)*(y1-y0));
             precompute[i] = (dist < eps) ? 0.0f : 1.0f / dist;
          } else if (verts[i].type == STBTT_vcurve) {
             float x2 = verts[j].x *scale_x, y2 = verts[j].y *scale_y;
             float x1 = verts[i].cx*scale_x, y1 = verts[i].cy*scale_y;
             float x0 = verts[i].x *scale_x, y0 = verts[i].y *scale_y;
             float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
             float len2 = bx*bx + by*by;
             if (len2 >= eps2)
                precompute[i] = 1.0f / len2;
             else
                precompute[i] = 0.0f;
          } else
             precompute[i] = 0.0f;
       }
 
       for (y=iy0; y < iy1; ++y) {
          for (x=ix0; x < ix1; ++x) {
             float val;
             float min_dist = 999999.0f;
             float sx = (float) x + 0.5f;
             float sy = (float) y + 0.5f;
             float x_gspace = (sx / scale_x);
             float y_gspace = (sy / scale_y);
 
             int winding = stbtt__compute_crossings_x(x_gspace, y_gspace, num_verts, verts); // @OPTIMIZE: this could just be a rasterization, but needs to be line vs. non-tesselated curves so a new path
 
             for (i=0; i < num_verts; ++i) {
                float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
 
                if (verts[i].type == STBTT_vline && precompute[i] != 0.0f) {
                   float x1 = verts[i-1].x*scale_x, y1 = verts[i-1].y*scale_y;
 
                   float dist,dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
                   if (dist2 < min_dist*min_dist)
                      min_dist = (float) STBTT_sqrt(dist2);
 
                   // coarse culling against bbox
                   //if (sx > STBTT_min(x0,x1)-min_dist && sx < STBTT_max(x0,x1)+min_dist &&
                   //    sy > STBTT_min(y0,y1)-min_dist && sy < STBTT_max(y0,y1)+min_dist)
                   dist = (float) STBTT_fabs((x1-x0)*(y0-sy) - (y1-y0)*(x0-sx)) * precompute[i];
                   STBTT_assert(i != 0);
                   if (dist < min_dist) {
                      // check position along line
                      // x' = x0 + t*(x1-x0), y' = y0 + t*(y1-y0)
                      // minimize (x'-sx)*(x'-sx)+(y'-sy)*(y'-sy)
                      float dx = x1-x0, dy = y1-y0;
                      float px = x0-sx, py = y0-sy;
                      // minimize (px+t*dx)^2 + (py+t*dy)^2 = px*px + 2*px*dx*t + t^2*dx*dx + py*py + 2*py*dy*t + t^2*dy*dy
                      // derivative: 2*px*dx + 2*py*dy + (2*dx*dx+2*dy*dy)*t, set to 0 and solve
                      float t = -(px*dx + py*dy) / (dx*dx + dy*dy);
                      if (t >= 0.0f && t <= 1.0f)
                         min_dist = dist;
                   }
                } else if (verts[i].type == STBTT_vcurve) {
                   float x2 = verts[i-1].x *scale_x, y2 = verts[i-1].y *scale_y;
                   float x1 = verts[i  ].cx*scale_x, y1 = verts[i  ].cy*scale_y;
                   float box_x0 = STBTT_min(STBTT_min(x0,x1),x2);
                   float box_y0 = STBTT_min(STBTT_min(y0,y1),y2);
                   float box_x1 = STBTT_max(STBTT_max(x0,x1),x2);
                   float box_y1 = STBTT_max(STBTT_max(y0,y1),y2);
                   // coarse culling against bbox to avoid computing cubic unnecessarily
                   if (sx > box_x0-min_dist && sx < box_x1+min_dist && sy > box_y0-min_dist && sy < box_y1+min_dist) {
                      int num=0;
                      float ax = x1-x0, ay = y1-y0;
                      float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
                      float mx = x0 - sx, my = y0 - sy;
                      float res[3] = {0.f,0.f,0.f};
                      float px,py,t,it,dist2;
                      float a_inv = precompute[i];
                      if (a_inv == 0.0) { // if a_inv is 0, it's 2nd degree so use quadratic formula
                         float a = 3*(ax*bx + ay*by);
                         float b = 2*(ax*ax + ay*ay) + (mx*bx+my*by);
                         float c = mx*ax+my*ay;
                         if (STBTT_fabs(a) < eps2) { // if a is 0, it's linear
                            if (STBTT_fabs(b) >= eps2) {
                               res[num++] = -c/b;
                            }
                         } else {
                            float discriminant = b*b - 4*a*c;
                            if (discriminant < 0)
                               num = 0;
                            else {
                               float root = (float) STBTT_sqrt(discriminant);
                               res[0] = (-b - root)/(2*a);
                               res[1] = (-b + root)/(2*a);
                               num = 2; // don't bother distinguishing 1-solution case, as code below will still work
                            }
                         }
                      } else {
                         float b = 3*(ax*bx + ay*by) * a_inv; // could precompute this as it doesn't depend on sample point
                         float c = (2*(ax*ax + ay*ay) + (mx*bx+my*by)) * a_inv;
                         float d = (mx*ax+my*ay) * a_inv;
                         num = stbtt__solve_cubic(b, c, d, res);
                      }
                      dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
                      if (dist2 < min_dist*min_dist)
                         min_dist = (float) STBTT_sqrt(dist2);
 
                      if (num >= 1 && res[0] >= 0.0f && res[0] <= 1.0f) {
                         t = res[0], it = 1.0f - t;
                         px = it*it*x0 + 2*t*it*x1 + t*t*x2;
                         py = it*it*y0 + 2*t*it*y1 + t*t*y2;
                         dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
                         if (dist2 < min_dist * min_dist)
                            min_dist = (float) STBTT_sqrt(dist2);
                      }
                      if (num >= 2 && res[1] >= 0.0f && res[1] <= 1.0f) {
                         t = res[1], it = 1.0f - t;
                         px = it*it*x0 + 2*t*it*x1 + t*t*x2;
                         py = it*it*y0 + 2*t*it*y1 + t*t*y2;
                         dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
                         if (dist2 < min_dist * min_dist)
                            min_dist = (float) STBTT_sqrt(dist2);
                      }
                      if (num >= 3 && res[2] >= 0.0f && res[2] <= 1.0f) {
                         t = res[2], it = 1.0f - t;
                         px = it*it*x0 + 2*t*it*x1 + t*t*x2;
                         py = it*it*y0 + 2*t*it*y1 + t*t*y2;
                         dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
                         if (dist2 < min_dist * min_dist)
                            min_dist = (float) STBTT_sqrt(dist2);
                      }
                   }
                }
             }
             if (winding == 0)
                min_dist = -min_dist;  // if outside the shape, value is negative
             val = onedge_value + pixel_dist_scale * min_dist;
             if (val < 0)
                val = 0;
             else if (val > 255)
                val = 255;
             data[(y-iy0)*w+(x-ix0)] = (unsigned char) val;
          }
       }
    }
    return data;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // font name matching -- recommended not to use this
 //
 
 // check if a utf8 string contains a prefix which is the utf16 string; if so return length of matching utf8 string
 static stbtt_int32 stbtt__CompareUTF8toUTF16_bigendian_prefix(s8 s1, s8 s2)
 {
    stbtt_int32 i=0;
 
    // convert utf16 to utf8 and compare the results while converting
    while (s2.len) {
       stbtt_uint16 ch = s2.data[0]*256 + s2.data[1];
       if (ch < 0x80) {
          if (i >= s1.len) return -1;
          if (s1.data[i++] != ch) return -1;
       } else if (ch < 0x800) {
          if (i+1 >= s1.len) return -1;
          if (s1.data[i++] != 0xc0 + (ch >> 6)) return -1;
          if (s1.data[i++] != 0x80 + (ch & 0x3f)) return -1;
       } else if (ch >= 0xd800 && ch < 0xdc00) {
          stbtt_uint32 c;
          stbtt_uint16 ch2 = s2.data[2]*256 + s2.data[3];
          if (i+3 >= s1.len) return -1;
          c = ((ch - 0xd800) << 10) + (ch2 - 0xdc00) + 0x10000;
          if (s1.data[i++] != 0xf0 + (c >> 18)) return -1;
          if (s1.data[i++] != 0x80 + ((c >> 12) & 0x3f)) return -1;
          if (s1.data[i++] != 0x80 + ((c >>  6) & 0x3f)) return -1;
          if (s1.data[i++] != 0x80 + ((c      ) & 0x3f)) return -1;
          s2.data += 2; // plus another 2 below
          s2.len  -= 2;
       } else if (ch >= 0xdc00 && ch < 0xe000) {
          return -1;
       } else {
          if (i+2 >= s1.len) return -1;
          if (s1.data[i++] != 0xe0 + (ch >> 12)) return -1;
          if (s1.data[i++] != 0x80 + ((ch >> 6) & 0x3f)) return -1;
          if (s1.data[i++] != 0x80 + ((ch     ) & 0x3f)) return -1;
       }
       s2.data += 2;
       s2.len  -= 2;
    }
    return i;
 }
 
 STBTT_DEF int stbtt_CompareUTF8toUTF16_bigendian(s8 s1, s8 s2)
 {
    return s1.len == stbtt__CompareUTF8toUTF16_bigendian_prefix(s1, s2);
 }
 
 // returns results in whatever encoding you request... but note that 2-byte encodings
 // will be BIG-ENDIAN... use stbtt_CompareUTF8toUTF16_bigendian() to compare
 STBTT_DEF const char *stbtt_GetFontNameString(const stbtt_fontinfo *font, int *length, int platformID, int encodingID, int languageID, int nameID)
 {
    stbtt_int32 i,count,stringOffset;
    stbtt_uint8 *fc = font->data;
    stbtt_uint32 offset = font->fontstart;
    stbtt_uint32 nm = stbtt__find_table(fc, offset, "name");
    if (!nm) return NULL;
 
    count = ttUSHORT(fc+nm+2);
    stringOffset = nm + ttUSHORT(fc+nm+4);
    for (i=0; i < count; ++i) {
       stbtt_uint32 loc = nm + 6 + 12 * i;
       if (platformID == ttUSHORT(fc+loc+0) && encodingID == ttUSHORT(fc+loc+2)
           && languageID == ttUSHORT(fc+loc+4) && nameID == ttUSHORT(fc+loc+6)) {
          *length = ttUSHORT(fc+loc+8);
          return (const char *) (fc+stringOffset+ttUSHORT(fc+loc+10));
       }
    }
    return NULL;
 }
 
 static int stbtt__matchpair(stbtt_uint8 *fc, stbtt_uint32 nm, s8 name, stbtt_int32 target_id, stbtt_int32 next_id)
 {
    stbtt_int32 i;
    stbtt_int32 count = ttUSHORT(fc+nm+2);
    stbtt_int32 stringOffset = nm + ttUSHORT(fc+nm+4);
 
    for (i=0; i < count; ++i) {
       stbtt_uint32 loc = nm + 6 + 12 * i;
       stbtt_int32 id = ttUSHORT(fc+loc+6);
       if (id == target_id) {
          // find the encoding
          stbtt_int32 platform = ttUSHORT(fc+loc+0), encoding = ttUSHORT(fc+loc+2), language = ttUSHORT(fc+loc+4);
 
          // is this a Unicode encoding?
          if (platform == 0 || (platform == 3 && encoding == 1) || (platform == 3 && encoding == 10)) {
             stbtt_int32 slen = ttUSHORT(fc+loc+8);
             stbtt_int32 off = ttUSHORT(fc+loc+10);
 
             // check if there's a prefix match
             s8 cmp = {.len = slen, .data = fc + stringOffset + off};
             stbtt_int32 matchlen = stbtt__CompareUTF8toUTF16_bigendian_prefix(name, cmp);
             if (matchlen >= 0) {
                // check for target_id+1 immediately following, with same encoding & language
                if (i+1 < count && ttUSHORT(fc+loc+12+6) == next_id && ttUSHORT(fc+loc+12) == platform && ttUSHORT(fc+loc+12+2) == encoding && ttUSHORT(fc+loc+12+4) == language) {
                   slen = ttUSHORT(fc+loc+12+8);
                   off = ttUSHORT(fc+loc+12+10);
                   if (slen == 0) {
                      if (matchlen == name.len)
                         return 1;
                   } else if (matchlen < name.len && name.data[matchlen] == ' ') {
                      ++matchlen;
                      s8 n = name;
                      n.data += matchlen;
                      n.len  -= matchlen;
                      if (stbtt_CompareUTF8toUTF16_bigendian(n, cmp))
                         return 1;
                   }
                } else {
                   // if nothing immediately following
                   if (matchlen == name.len)
                      return 1;
                }
             }
          }
 
          // @TODO handle other encodings
       }
    }
    return 0;
 }
 
 static int stbtt__matches(stbtt_uint8 *fc, stbtt_uint32 offset, s8 name, stbtt_int32 flags)
 {
    stbtt_uint32 nm,hd;
    if (!stbtt__isfont(fc+offset)) return 0;
 
    // check italics/bold/underline flags in macStyle...
    if (flags) {
       hd = stbtt__find_table(fc, offset, "head");
       if ((ttUSHORT(fc+hd+44) & 7) != (flags & 7)) return 0;
    }
 
    nm = stbtt__find_table(fc, offset, "name");
    if (!nm) return 0;
 
    if (flags) {
       // if we checked the macStyle flags, then just check the family and ignore the subfamily
       if (stbtt__matchpair(fc, nm, name, 16, -1))  return 1;
       if (stbtt__matchpair(fc, nm, name,  1, -1))  return 1;
       if (stbtt__matchpair(fc, nm, name,  3, -1))  return 1;
    } else {
       if (stbtt__matchpair(fc, nm, name, 16, 17))  return 1;
       if (stbtt__matchpair(fc, nm, name,  1,  2))  return 1;
       if (stbtt__matchpair(fc, nm, name,  3, -1))  return 1;
    }
 
    return 0;
 }
 
 STBTT_DEF int stbtt_FindMatchingFont(unsigned char *font_collection, s8 name_utf8, stbtt_int32 flags)
 {
    stbtt_int32 i;
    for (i=0;;++i) {
       stbtt_int32 off = stbtt_GetFontOffsetForIndex(font_collection, i);
       if (off < 0) return off;
       if (stbtt__matches((stbtt_uint8 *) font_collection, off, name_utf8, flags))
          return off;
    }
 }
 
 #endif // STB_TRUETYPE_IMPLEMENTATION
 
 
 // FULL VERSION HISTORY
 //
 //   1.25 (2021-07-11) many fixes
 //   1.24 (2020-02-05) fix warning
 //   1.23 (2020-02-02) query SVG data for glyphs; query whole kerning table (but only kern not GPOS)
 //   1.22 (2019-08-11) minimize missing-glyph duplication; fix kerning if both 'GPOS' and 'kern' are defined
 //   1.21 (2019-02-25) fix warning
 //   1.20 (2019-02-07) PackFontRange skips missing codepoints; GetScaleFontVMetrics()
 //   1.19 (2018-02-11) OpenType GPOS kerning (horizontal only), STBTT_fmod
 //   1.18 (2018-01-29) add missing function
 //   1.17 (2017-07-23) make more arguments const; doc fix
 //   1.16 (2017-07-12) SDF support
 //   1.15 (2017-03-03) make more arguments const
 //   1.14 (2017-01-16) num-fonts-in-TTC function
 //   1.13 (2017-01-02) support OpenType fonts, certain Apple fonts
 //   1.12 (2016-10-25) suppress warnings about casting away const with -Wcast-qual
 //   1.11 (2016-04-02) fix unused-variable warning
 //   1.10 (2016-04-02) allow user-defined fabs() replacement
 //                     fix memory leak if fontsize=0.0
 //                     fix warning from duplicate typedef
 //   1.09 (2016-01-16) warning fix; avoid crash on outofmem; use alloc userdata for PackFontRanges
 //   1.08 (2015-09-13) document stbtt_Rasterize(); fixes for vertical & horizontal edges
 //   1.07 (2015-08-01) allow PackFontRanges to accept arrays of sparse codepoints;
 //                     allow PackFontRanges to pack and render in separate phases;
 //                     fix stbtt_GetFontOFfsetForIndex (never worked for non-0 input?);
 //                     fixed an assert() bug in the new rasterizer
 //                     replace assert() with STBTT_assert() in new rasterizer
 //   1.06 (2015-07-14) performance improvements (~35% faster on x86 and x64 on test machine)
 //                     also more precise AA rasterizer, except if shapes overlap
 //                     remove need for STBTT_sort
 //   1.05 (2015-04-15) fix misplaced definitions for STBTT_STATIC
 //   1.04 (2015-04-15) typo in example
 //   1.03 (2015-04-12) STBTT_STATIC, fix memory leak in new packing, various fixes
 //   1.02 (2014-12-10) fix various warnings & compile issues w/ stb_rect_pack, C++
 //   1.01 (2014-12-08) fix subpixel position when oversampling to exactly match
 //                        non-oversampled; STBTT_POINT_SIZE for packed case only
 //   1.00 (2014-12-06) add new PackBegin etc. API, w/ support for oversampling
 //   0.99 (2014-09-18) fix multiple bugs with subpixel rendering (ryg)
 //   0.9  (2014-08-07) support certain mac/iOS fonts without an MS platformID
 //   0.8b (2014-07-07) fix a warning
 //   0.8  (2014-05-25) fix a few more warnings
 //   0.7  (2013-09-25) bugfix: subpixel glyph bug fixed in 0.5 had come back
 //   0.6c (2012-07-24) improve documentation
 //   0.6b (2012-07-20) fix a few more warnings
 //   0.6  (2012-07-17) fix warnings; added stbtt_ScaleForMappingEmToPixels,
 //                        stbtt_GetFontBoundingBox, stbtt_IsGlyphEmpty
 //   0.5  (2011-12-09) bugfixes:
 //                        subpixel glyph renderer computed wrong bounding box
 //                        first vertex of shape can be off-curve (FreeSans)
 //   0.4b (2011-12-03) fixed an error in the font baking example
 //   0.4  (2011-12-01) kerning, subpixel rendering (tor)
 //                    bugfixes for:
 //                        codepoint-to-glyph conversion using table fmt=12
 //                        codepoint-to-glyph conversion using table fmt=4
 //                        stbtt_GetBakedQuad with non-square texture (Zer)
 //                    updated Hello World! sample to use kerning and subpixel
 //                    fixed some warnings
 //   0.3  (2009-06-24) cmap fmt=12, compound shapes (MM)
 //                    userdata, malloc-from-userdata, non-zero fill (stb)
 //   0.2  (2009-03-11) Fix unsigned/signed char warnings
 //   0.1  (2009-03-09) First public release
 //
 
 /*
 ------------------------------------------------------------------------------
 This software is available under 2 licenses -- choose whichever you prefer.
 ------------------------------------------------------------------------------
 ALTERNATIVE A - MIT License
 Copyright (c) 2017 Sean Barrett
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in
 the Software without restriction, including without limitation the rights to
 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 of the Software, and to permit persons to whom the Software is furnished to do
 so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ------------------------------------------------------------------------------
 ALTERNATIVE B - Public Domain (www.unlicense.org)
 This is free and unencumbered software released into the public domain.
 Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
 software, either in source code form or as a compiled binary, for any purpose,
 commercial or non-commercial, and by any means.
 In jurisdictions that recognize copyright laws, the author or authors of this
 software dedicate any and all copyright interest in the software to the public
 domain. We make this dedication for the benefit of the public at large and to
 the detriment of our heirs and successors. We intend this dedication to be an
 overt act of relinquishment in perpetuity of all present and future rights to
 this software under copyright law.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 ------------------------------------------------------------------------------
 */