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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 <emscripten/emscripten.h>
#include <emscripten/html5.h>
#include <GLES2/gl2.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);
glGetShaderInfoLog(shader, maxLength, NULL, 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
#ifdef DRAW_FROM_CLIENT_MEMORY
// This test verifies that drawing from client-side memory when enableExtensionsByDefault==false works.
attr.enableExtensionsByDefault = 0;
#endif
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context("#canvas", &attr);
emscripten_webgl_make_context_current(ctx);
static const char vertex_shader[] =
"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[] =
"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 float pos_and_color[] = {
// x, y, r, g, b
-0.6f, -0.6f, 1, 0, 0,
0.6f, -0.6f, 0, 1, 0,
0.f, 0.6f, 0, 0, 1,
};
#ifdef DRAW_FROM_CLIENT_MEMORY
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 20, pos_and_color);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 20, (void*)(pos_and_color+2));
#else
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, 2, GL_FLOAT, GL_FALSE, 20, 0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 20, (void*)8);
#endif
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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