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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 <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <emscripten/emscripten.h>
#include <emscripten/html5.h>
#include <GLES3/gl3.h>
GLuint compile_shader(GLenum shaderType, const char *src)
{
GLuint shader = glCreateShader(shaderType);
glShaderSource(shader, 1, &src, NULL);
glCompileShader(shader);
GLint isCompiled = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, &isCompiled);
if (!isCompiled)
{
GLint maxLength = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &maxLength);
char *buf = (char*)malloc(maxLength+1);
glGetShaderInfoLog(shader, maxLength, &maxLength, buf);
printf("%s\n", buf);
free(buf);
return 0;
}
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;
}
int main()
{
EmscriptenWebGLContextAttributes attr;
emscripten_webgl_init_context_attributes(&attr);
#ifdef EXPLICIT_SWAP
attr.explicitSwapControl = 1;
#endif
attr.majorVersion = 2;
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context("#canvas", &attr);
assert(ctx && "Failed to create WebGL2 context");
emscripten_webgl_make_context_current(ctx);
static const char vertex_shader[] =
"#version 100\n"
"attribute vec4 apos;"
"attribute vec4 acolor;"
"varying vec4 color;"
"void main() {"
"color = acolor;"
"gl_Position = apos;"
"}";
GLuint vs = compile_shader(GL_VERTEX_SHADER, vertex_shader);
static const char fragment_shader[] =
"#version 100\n"
"precision lowp float;"
"varying vec4 color;"
"void main() {"
"gl_FragColor = color;"
"}";
GLuint fs = compile_shader(GL_FRAGMENT_SHADER, fragment_shader);
GLuint program = create_program(vs, fs);
glUseProgram(program);
static const uint32_t pos_and_color[] = {
// 1,0,y,x, a,b,g,r
0x400b36cd, 0xc00003ff,
0x400b3533, 0xc00ffc00,
0x4004cc00, 0xfff00000,
};
GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(pos_and_color), pos_and_color, GL_STATIC_DRAW);
glVertexAttribPointer(0, 4, GL_INT_2_10_10_10_REV, GL_TRUE, 8, 0);
assert(glGetError() == GL_NO_ERROR && "glVertexAttribPointer with GL_INT_2_10_10_10_REV failed");
glVertexAttribPointer(1, 4, GL_UNSIGNED_INT_2_10_10_10_REV, GL_TRUE, 8, (void*)4);
assert(glGetError() == GL_NO_ERROR && "glVertexAttribPointer with GL_UNSIGNED_INT_2_10_10_10_REV failed");
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glClearColor(0.3f,0.3f,0.3f,1);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 3);
#ifdef EXPLICIT_SWAP
emscripten_webgl_commit_frame();
#endif
return 0;
}
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