vtgl

Commit: e080b99dc9c1f0f62c13f1ff6aa7fe41e471860f
Parent: e1a7bae479960e5c64543c691955941fb1e05c6d
Author: Randy Palamar
Date:   Mon, 26 Aug 2024 21:09:39 -0600

avoid redrawing the whole framebuffer if it hasn't updated

This is a first pass at reducing CPU usage. We still the render
texture on each frame which allows post processing to take effect.
Since this is a simple fullscreen textured quad it requires
minimal processing power.

Diffstat:
M
terminal.c
 | 
7
++++---
M
util.c
 | 
7
+++++++
M
util.h
 | 
4
+++-
M
vtgl.c
 | 
98
+++++++++++++++++++++++++++++++++++++++++--------------------------------------

4 files changed, 65 insertions(+), 51 deletions(-)
diff --git a/terminal.c b/terminal.c
@@ -235,7 +235,7 @@ swap_screen(Term *t)
 {
 	t->mode     ^= TM_ALTSCREEN;
 	t->view_idx  = !!(t->mode & TM_ALTSCREEN);
-	t->gl.flags |= NEEDS_FULL_BLIT;
+	t->gl.flags |= NEEDS_FULL_REFILL;
 }
 
 static void
@@ -1140,7 +1140,7 @@ blit_lines(Term *t, Arena a, size line_count)
 {
 	TermView *tv = t->views + t->view_idx;
 
-	if (t->gl.flags & NEEDS_FULL_BLIT) {
+	if (t->gl.flags & NEEDS_FULL_REFILL) {
 		term_reset(t);
 		line_count = t->size.h - 1;
 	}
@@ -1156,5 +1156,6 @@ blit_lines(Term *t, Arena a, size line_count)
 		push_line(t, tv->lines.buf + line_idx, a);
 	}
 
-	t->gl.flags &= ~(NEEDS_FULL_BLIT|NEEDS_BLIT);
+	t->gl.flags &= ~(NEEDS_FULL_REFILL|NEEDS_REFILL);
+	t->gl.flags |= NEEDS_BLIT;
 }
diff --git a/util.c b/util.c
@@ -11,6 +11,13 @@ equal_iv2(iv2 a, iv2 b)
 }
 
 static b32
+equal_uv2(uv2 a, uv2 b)
+{
+	b32 result = a.x == b.x && a.y == b.y;
+	return result;
+}
+
+static b32
 is_valid_range(Range r)
 {
 	b32 result = !equal_iv2(r.end, INVALID_RANGE_END);
diff --git a/util.h b/util.h
@@ -195,7 +195,9 @@ typedef struct {
 enum gl_flags {
 	NEEDS_RESIZE           = 1 << 0,
 	NEEDS_BLIT             = 1 << 1,
-	NEEDS_FULL_BLIT        = 1 << 2,
+	NEEDS_REFILL           = 1 << 2,
+	NEEDS_FULL_REFILL      = 1 << 3,
+
 	UPDATE_RENDER_UNIFORMS = 1 << 29,
 	UPDATE_POST_UNIFORMS   = 1 << 30,
 };
diff --git a/vtgl.c b/vtgl.c
@@ -104,16 +104,19 @@ resize(Term *t)
 	ws.w  -= 2 * g_term_pad.w;
 	ws.h  -= 2 * g_term_pad.h;
 
-	v2 cs     = get_cell_size(t);
-	t->size.w = (u32)(ws.w / cs.w);
-	t->size.h = (u32)(ws.h / cs.h);
+	uv2 old_size = t->size;
+	v2 cs        = get_cell_size(t);
+	t->size.w    = (u32)(ws.w / cs.w);
+	t->size.h    = (u32)(ws.h / cs.h);
+
+	if (!equal_uv2(old_size, t->size)) {
+		os_alloc_framebuffer(&t->views[0].fb, t->size.h, t->size.w);
+		os_alloc_framebuffer(&t->views[1].fb, t->size.h, t->size.w);
+		t->gl.flags |= NEEDS_FULL_REFILL;
+	}
 
-	os_alloc_framebuffer(&t->views[0].fb, t->size.h, t->size.w);
-	os_alloc_framebuffer(&t->views[1].fb, t->size.h, t->size.w);
 	os_set_term_size(t->child, t->size.h, t->size.w, ws.w, ws.h);
 	t->gl.flags &= ~NEEDS_RESIZE;
-	/* TODO: check if we actually changed size */
-	t->gl.flags |= NEEDS_FULL_BLIT;
 }
 
 static void
@@ -450,7 +453,8 @@ update_selection(Term *t)
 			}
 		}
 	}
-	sel->range = normalize_range(sel->range);
+	sel->range   = normalize_range(sel->range);
+	t->gl.flags |= NEEDS_BLIT;
 }
 
 KEYBIND_FN(copy)
@@ -535,7 +539,7 @@ KEYBIND_FN(scroll)
 	t->scroll_offset += a.i;
 	CLAMP(t->scroll_offset, 0, tv->lines.filled - (t->size.h - 1));
 
-	t->gl.flags |= NEEDS_FULL_BLIT;
+	t->gl.flags |= NEEDS_FULL_REFILL;
 
 	return 1;
 }
@@ -708,7 +712,7 @@ char_callback(GLFWwindow *win, u32 codepoint)
 	Term *t = glfwGetWindowUserPointer(win);
 	if (t->scroll_offset) {
 		t->scroll_offset = 0;
-		t->gl.flags |= NEEDS_FULL_BLIT;
+		t->gl.flags |= NEEDS_FULL_REFILL;
 	}
 	os_child_put_char(t->child, codepoint);
 }
@@ -791,58 +795,58 @@ do_terminal(Term *t)
 			.data = rb->buf + (rb->widx - t->unprocessed_bytes)
 		};
 		parsed_lines  = split_raw_input_to_lines(t, raw);
-		t->gl.flags  |= NEEDS_BLIT;
+		t->gl.flags  |= NEEDS_REFILL;
 	}
 
-	if (t->gl.flags & (NEEDS_BLIT|NEEDS_FULL_BLIT))
+	if (t->gl.flags & (NEEDS_REFILL|NEEDS_FULL_REFILL))
 		blit_lines(t, t->arena_for_frame, parsed_lines);
 
 	update_selection(t);
 
-	/* NOTE: reset the camera/viewport */
-	glUseProgram(t->gl.programs[SHADER_RENDER]);
-	glUniform1i(t->gl.render.texslot, 0);
-	glBindFramebuffer(GL_FRAMEBUFFER, t->gl.fb);
+	v2 ws = t->gl.window_size;
 
-	RenderPushBuffer *rpb = alloc(&t->arena_for_frame, RenderPushBuffer, 1);
-	clear_colour();
-	render_framebuffer(t, rpb);
+	if (t->gl.flags & NEEDS_BLIT) {
+		glUseProgram(t->gl.programs[SHADER_RENDER]);
+		glUniform1i(t->gl.render.texslot, 0);
+		glBindFramebuffer(GL_FRAMEBUFFER, t->gl.fb);
 
-	v2 ws = t->gl.window_size;
+		RenderPushBuffer *rpb = alloc(&t->arena_for_frame, RenderPushBuffer, 1);
+		clear_colour();
+		render_framebuffer(t, rpb);
 
-	if (0) {
-		v2 cell_size  = get_cell_size(t);
-		v2 cursor_pos = {
-			.x = t->cursor.pos.x * cell_size.w,
-			.y = ws.h - cell_size.h * (t->cursor.pos.y + 1),
-		};
+		if (0) {
+			v2 cell_size  = get_cell_size(t);
+			v2 cursor_pos = {
+				.x = t->cursor.pos.x * cell_size.w,
+				.y = ws.h - cell_size.h * (t->cursor.pos.y + 1),
+			};
 
-		v2 src_bl = {0};
-		v2 src_tr = { .x = ws.w, .y = src_bl.y + ws.h };
+			v2 src_bl = {0};
+			v2 src_tr = {.x = ws.w, .y = src_bl.y + ws.h};
 
-		if (t->cursor.pos.y > t->size.h) {
-			src_tr.y = cursor_pos.y + ws.h;
-			src_bl.y = cursor_pos.y;
-		}
+			if (t->cursor.pos.y > t->size.h) {
+				src_tr.y = cursor_pos.y + ws.h;
+				src_bl.y = cursor_pos.y;
+			}
 
-		s8 fps  = s8alloc(&t->arena_for_frame, 64);
-		fps.len = snprintf((char *)fps.data, fps.len, "Render Time: %0.02f ms/f", last_frame_time * 1e3);
-		v2 ts   = measure_text(&t->gl, fps, 1);
-		v2 pos  = {
-			.x = ws.w - ts.x - 10,
-			.y = src_tr.y - ts.y - 10
-		};
+			s8 fps  = s8alloc(&t->arena_for_frame, 64);
+			fps.len = snprintf((char *)fps.data, fps.len, "Render Time: %0.02f ms/f",
+			                   last_frame_time * 1e3);
+			v2 ts   = measure_text(&t->gl, fps, 1);
+			v2 pos  = {.x = ws.w - ts.x - 10, .y = src_tr.y - ts.y - 10};
 
-		Rect r = {
-			.pos  = {.x = pos.x - 0.05 * ts.x, .y = pos.y - 0.25 * ts.y},
-			.size = {.w = ts.w * 1.1, .h = ts.h * 1.2},
-		};
+			Rect r = {
+				.pos  = {.x = pos.x - 0.05 * ts.x, .y = pos.y - 0.25 * ts.y},
+				.size = {.w = ts.w * 1.1, .h = ts.h * 1.2},
+			};
 
-		draw_rectangle(rpb, &t->gl, r, (Colour){.rgba = 0x303030ff});
-		draw_text(rpb, &t->gl, fps, pos, (Colour){.rgba = 0x1e9e33ff}, 1);
-	}
+			draw_rectangle(rpb, &t->gl, r, (Colour){.rgba = 0x303030ff});
+			draw_text(rpb, &t->gl, fps, pos, (Colour){.rgba = 0x1e9e33ff}, 1);
+		}
 
-	flush_render_push_buffer(rpb, &t->gl);
+		flush_render_push_buffer(rpb, &t->gl);
+		t->gl.flags &= ~NEEDS_BLIT;
+	}
 
 	static f32 param = 0;
 	static f32 p_scale = 1;