From edc565c2b82e3c189aa88f48a408492b4ff60e49 Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Sat, 13 May 2017 22:10:36 -0400
Subject: switch from gles 3.2 to gl core 4.5, to real compute shader, and bump
 workgroup size to 128

---
 main.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

(limited to 'main.c')

diff --git a/main.c b/main.c
index cc4976d..04eb4ce 100644
--- a/main.c
+++ b/main.c
@@ -32,7 +32,7 @@
 
 // use compute shader to update particles?
 // (if false, map the buffer and populate it on the cpu)
-#define USE_COMPUTE_SHADER false
+#define USE_COMPUTE_SHADER true
 
 // enable gl debug
 #define USE_GL_DEBUG false
@@ -41,7 +41,7 @@
 #define NUM_PARTICLES 1024
 
 // size of compute shader workgroups
-#define WORKGROUP_SIZE 1
+#define WORKGROUP_SIZE 128
 
 typedef struct {
   const GLuint type;
@@ -85,11 +85,10 @@ typedef struct {
   "  mediump vec4 colors[" S(NUM_PARTICLES) "];\n"      \
   "};\n"
 
-#if 0
 // real compute shader
 static const char
 cs_src[] =
-  "#version 320 es\n"
+  "#version 450 core\n"
 #if USE_GL_DEBUG
   "#pragma debug(on)\n"
 #endif /* USE_GL_DEBUG */
@@ -101,20 +100,24 @@ cs_src[] =
   "void main() {\n"
   "  mediump uint i = gl_GlobalInvocationID.x;\n"
   "  positions[i] += 0.016 * velocities[i];\n"
+  "\n"
+  "  if (positions[i].x > 1.1) {\n"
+  "    positions[i].x -= 2.2;\n"
+  "  } else if (positions[i].x < -1.1) {\n"
+  "    positions[i].x += 2.2;\n"
+  "  }\n"
+  "\n"
+  "  if (positions[i].y > 1.1) {\n"
+  "    positions[i].y -= 2.2;\n"
+  "  } else if (positions[i].y < -1.1) {\n"
+  "    positions[i].y += 2.2;\n"
+  "  }\n"
   "}\n";
-#endif /* 0 */
-
-// empty compute shader
-static const char
-cs_src[] =
-  "#version 320 es\n"
-  "layout(local_size_x = " S(WORKGROUP_SIZE) ") in;\n"
-  "void main() {}\n";
 
 // vertex shader
 static const char
 vs_src[] =
-  "#version 320 es\n"
+  "#version 450 core\n"
   "\n"
   PARTICLE_BUFFER
   "\n"
@@ -129,7 +132,7 @@ vs_src[] =
 // fragment shader
 static const char
 fs_src[] =
-  "#version 320 es\n"
+  "#version 450 core\n"
   "\n"
   PARTICLE_BUFFER
   "\n"
@@ -451,20 +454,20 @@ ctx_init(context_t * const ctx) {
   // set gl context majory version hint
   if (SDL_GL_SetAttribute(
     SDL_GL_CONTEXT_PROFILE_MASK,
-    SDL_GL_CONTEXT_PROFILE_ES
+    SDL_GL_CONTEXT_PROFILE_CORE
   ) < 0) {
     LOG_C("SDL_GL_SetAttribute() failed: %s", SDL_GetError());
     exit(EXIT_FAILURE);
   }
 
   // set gl context majory version hint
-  if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3) < 0) {
+  if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4) < 0) {
     LOG_C("SDL_GL_SetAttribute() failed: %s", SDL_GetError());
     exit(EXIT_FAILURE);
   }
 
   // set gl context minor version hint
-  if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2) < 0) {
+  if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 5) < 0) {
     LOG_C("SDL_GL_SetAttribute() failed: %s", SDL_GetError());
     exit(EXIT_FAILURE);
   }
-- 
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