ogl_beamforming

Commit: 56b8c6e685692d301c3340fa8eccc0d303d6e100
Parent: 0d7e5e3f8abcd482e616e918c38277e251503b01
Author: Randy Palamar
Date:   Tue, 18 Jun 2024 16:04:05 -0600

add extra rf data buffers for decoding and uploading

Diffstat:
M
beamformer.c
 | 
16
+++++++++++-----
M
main.c
 | 
4
+++-
M
util.c
 | 
9
++++++++-

3 files changed, 22 insertions(+), 7 deletions(-)
diff --git a/beamformer.c b/beamformer.c
@@ -3,6 +3,7 @@
 #include <raylib.h>
 #include <rlgl.h>
 
+#include <stdatomic.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -15,12 +16,12 @@
 #include "util.c"
 
 static void
-do_compute_shader(BeamformerCtx *ctx, enum compute_shaders shader)
+do_compute_shader(BeamformerCtx *ctx, u32 rf_ssbo_idx, enum compute_shaders shader)
 {
 	ComputeShaderCtx *csctx = &ctx->csctx;
 	glUseProgram(csctx->programs[shader]);
 
-	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, csctx->rf_data_ssbo);
+	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, csctx->rf_data_ssbos[rf_ssbo_idx]);
 	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, ctx->out_data_ssbo);
 
 	glUniform3uiv(csctx->rf_data_dim_id,  1, csctx->rf_data_dim.E);
@@ -60,11 +61,16 @@ do_beamformer(BeamformerCtx *ctx, Arena arena, s8 rf_data)
 		scale.y *= -1.0;
 	}
 
-	/* Load RF Data into GPU */
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, ctx->csctx.rf_data_ssbo);
+	/* NOTE: grab operating idx and swap it; other buffer can now be used for storage */
+	u32 rf_ssbo_idx = atomic_fetch_xor_explicit(&ctx->csctx.rf_data_idx, 1, memory_order_relaxed);
+	ASSERT(rf_ssbo_idx == 0 || rf_ssbo_idx == 1);
+
+	/* NOTE: Load RF Data into GPU */
+	/* TODO: This should be done in a seperate thread */
+	glBindBuffer(GL_SHADER_STORAGE_BUFFER, ctx->csctx.rf_data_ssbos[!rf_ssbo_idx]);
 	glBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, rf_data.len, rf_data.data);
 
-	do_compute_shader(ctx, CS_UFORCES);
+	do_compute_shader(ctx, rf_ssbo_idx, CS_UFORCES);
 
 	BeginDrawing();
 
diff --git a/main.c b/main.c
@@ -110,7 +110,9 @@ init_compute_shader_ctx(ComputeShaderCtx *ctx, uv3 rf_data_dim)
 
 	ctx->rf_data_dim  = rf_data_dim;
 	size rf_data_size = rf_data_dim.w * rf_data_dim.h * rf_data_dim.d * sizeof(f32);
-	ctx->rf_data_ssbo = rlLoadShaderBuffer(rf_data_size,  NULL, GL_DYNAMIC_COPY);
+	for (u32 i = 0; i < ARRAY_COUNT(ctx->rf_data_ssbos); i++)
+		ctx->rf_data_ssbos[i] = rlLoadShaderBuffer(rf_data_size, NULL, GL_DYNAMIC_COPY);
+	ctx->rf_data_idx = 0;
 }
 
 static void
diff --git a/util.c b/util.c
@@ -67,7 +67,14 @@ enum program_flags {
 typedef struct {
 	u32 programs[CS_LAST];
 
-	u32 rf_data_ssbo;
+	/* need 3 storage buffers: incoming rf data, currently decoding rf data, decoded data.
+	 * last buffer will always be for decoded data. other two will swap everytime there
+	 * is new data. current operating idx is stored in rf_data_idx (0 or 1) which needs
+	 * to be accessed atomically
+	 */
+	u32 rf_data_ssbos[3];
+	_Atomic u32 rf_data_idx;
+
 	uv3 rf_data_dim;
 	i32 rf_data_dim_id;
 	i32 out_data_dim_id;