From c77d329d13172d4bc0388e42295af0216293084a Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Fri, 12 May 2017 12:06:02 -0400
Subject: add instanced draw with uniform buffer
---
main.c | 31 +++++++++++++++++++++++++++----
1 file changed, 27 insertions(+), 4 deletions(-)
diff --git a/main.c b/main.c
index b26de0d..e6aded0 100644
--- a/main.c
+++ b/main.c
@@ -42,16 +42,29 @@ static const char
vs_src[] =
"#version 320 es\n"
"\n"
+ "layout (std140, binding = 0) uniform particles {\n"
+ " mediump vec4 positions[1000];\n"
+ " mediump vec4 velocities[1000];\n"
+ " mediump vec4 colors[1000];\n"
+ "};\n"
+ "\n"
"layout (location = 0) in mediump vec3 pos;\n"
"\n"
"void main() {\n"
- " gl_Position = vec4(pos.x, pos.y, pos.z, 1);\n"
+ " mediump float ofs = 0.002 * float(gl_InstanceID - 500);\n"
+ " gl_Position = vec4(pos.x - ofs, pos.y, pos.z, 1);\n"
"}\n";
static const char
fs_src[] =
"#version 320 es\n"
"\n"
+ "layout (std140, binding = 0) uniform particles {\n"
+ " mediump vec4 positions[1000];\n"
+ " mediump vec4 velocities[1000];\n"
+ " mediump vec4 colors[1000];\n"
+ "};\n"
+ "\n"
"out mediump vec4 color;\n"
"\n"
"uniform mediump float time;\n"
@@ -222,7 +235,7 @@ ctx_init(context_t * const ctx) {
}
// init times ring buffer
- memset(ctx->times, 0, MAX_TIMES * sizeof(uint32_t) * 2);
+ // memset(ctx->times, 0, sizeof(ctx->times));
ctx->times_ofs = 0;
// init flags
@@ -288,7 +301,7 @@ handle_events(
if (ev.user.code == EVENT_CODE_TIMER) {
uint32_t sum = 0;
- #pragma omp parallel for reduction(+:sum)
+ // #pragma omp parallel for reduction(+:sum)
for (int i = 0; i < MAX_TIMES; i++) {
sum += ctx->times[i].draw_end - ctx->times[i].draw_start;
}
@@ -339,6 +352,16 @@ int main(int argc, char *argv[]) {
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
+ // generate uniform buffer
+ GLuint ubo;
+ glGenBuffers(1, &ubo);
+ glBindBuffer(GL_UNIFORM_BUFFER, ubo);
+ glBufferData(GL_UNIFORM_BUFFER, 1000 * 3 * 4 * sizeof(GLfloat), NULL, GL_STATIC_DRAW);
+ glBindBuffer(GL_UNIFORM_BUFFER, 0);
+
+ // bind uniform buffer to slot 0
+ glBindBufferBase(GL_UNIFORM_BUFFER, 2, ubo);
+
// generate vertex buffer
GLuint vbo;
glGenBuffers(1, &vbo);
@@ -373,7 +396,7 @@ int main(int argc, char *argv[]) {
// draw
glBindVertexArray(vao);
- glDrawArrays(GL_TRIANGLES, 0, 3);
+ glDrawArraysInstanced(GL_TRIANGLES, 0, 3, 1000);
glBindVertexArray(0);
// swap buffer
--
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