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/*
* Copyright 2018 The Emscripten Authors. All rights reserved.
* Emscripten is available under two separate licenses, the MIT license and the
* University of Illinois/NCSA Open Source License. Both these licenses can be
* found in the LICENSE file.
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <emscripten/emscripten.h>
#include <emscripten/html5.h>
#include <webgl/webgl1.h>
#include <webgl/webgl1_ext.h>
#include <vector>
#define NUM_SHADERS_TO_LINK 100
GLuint compile_shader(GLenum shaderType, const char *src)
{
GLuint shader = glCreateShader(shaderType);
glShaderSource(shader, 1, &src, NULL);
glCompileShader(shader);
return shader;
}
GLuint create_program(GLuint vertexShader, GLuint fragmentShader)
{
GLuint program = glCreateProgram();
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
glBindAttribLocation(program, 0, "apos");
glBindAttribLocation(program, 1, "acolor");
glLinkProgram(program);
return program;
}
bool check_program_link_completed(GLuint program)
{
GLint completed = 0;
glGetProgramiv(program, GL_COMPLETION_STATUS_KHR, &completed);
return completed;
}
double linkStart = 0;
int numRafFramesElapsed = 0;
int numShadersPending = 0;
std::vector<std::pair<GLuint, double> > pendingLinks;
int parallel_shader_compile_is_working = 0;
EM_BOOL tick(double, void*)
{
for(size_t i = 0; i < pendingLinks.size(); ++i)
{
if (pendingLinks[i].first && check_program_link_completed(pendingLinks[i].first))
{
double elapsed = emscripten_get_now() - pendingLinks[i].second;
printf("Shader %d link completed in %d rAF frames/%f msecs.\n", (int)i, numRafFramesElapsed, elapsed);
pendingLinks[i].first = 0;
--numShadersPending;
// This is how we detect that parallel shader compilation must be working: spawning NUM_SHADERS_TO_LINK shader
// compiles cannot all finish within a single rAF() period, so some of them must finish after the first rAF.
// If they all finished within the first rAF(), they must have gotten synchronously linked in main().
if (numRafFramesElapsed > 0)
parallel_shader_compile_is_working = 1;
}
}
if (numShadersPending == 0)
{
printf("All shaders linked in %f msecs. parallel_shader_compile_is_working=%d\n", emscripten_get_now() - linkStart, parallel_shader_compile_is_working);
assert(parallel_shader_compile_is_working);
emscripten_force_exit(0);
}
++numRafFramesElapsed;
return EM_TRUE;
}
int main()
{
EmscriptenWebGLContextAttributes attr;
emscripten_webgl_init_context_attributes(&attr);
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context("#canvas", &attr);
emscripten_webgl_make_context_current(ctx);
EM_BOOL supported = emscripten_webgl_enable_extension(ctx, "KHR_parallel_shader_compile");
if (!supported)
{
printf("Skipping test, KHR_parallel_shader_compile WebGL extension is not supported.\n");
return 0;
}
linkStart = emscripten_get_now();
for(int i = 0; i < NUM_SHADERS_TO_LINK; ++i)
{
char shader[256];
sprintf(shader,
"attribute vec4 apos;"
"attribute vec4 acolor;"
"varying vec4 color;"
"void main() {"
"color = acolor;"
"gl_Position = apos + vec4(%f,%f,%f,0.0);"
"}", (float)i, (float)i, (float)i);
GLuint vs = compile_shader(GL_VERTEX_SHADER, shader);
sprintf(shader,
"precision lowp float;"
"varying vec4 color;"
"void main() {"
"gl_FragColor = color + vec4(%f,%f,%f,0.0);"
"}", (float)i, (float)i, (float)i);
GLuint fs = compile_shader(GL_FRAGMENT_SHADER, shader);
GLuint program = create_program(vs, fs);
pendingLinks.push_back(std::make_pair(program, emscripten_get_now()));
}
numShadersPending = pendingLinks.size();
printf("Issuing %d shader links took %f msecs.\n", numShadersPending, emscripten_get_now() - linkStart);
emscripten_request_animation_frame_loop(tick, 0);
}
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