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// Copyright 2021 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 <string.h>
#include <assert.h>
#include <emscripten/emscripten.h>
#include <emscripten/html5.h>
#include <GLES2/gl2.h>
#include <stdlib.h>
GLuint CompileShader(GLenum type, const char *src)
{
GLuint shader = glCreateShader(type);
glShaderSource(shader, 1, &src, NULL);
glCompileShader(shader);
assert(glGetError() == GL_NO_ERROR && "Shader compilation failed!");
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 CreateProgram(GLuint vertexShader, GLuint fragmentShader)
{
GLuint program = glCreateProgram();
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
glBindAttribLocation(program, 0, "pos");
glLinkProgram(program);
GLint linked = 0;
glGetProgramiv(program, GL_LINK_STATUS, &linked);
if (!linked)
{
GLint infoLen = 0;
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLen);
if (infoLen)
{
char *infoLog = (char*)malloc(infoLen);
glGetProgramInfoLog(program, infoLen, NULL, infoLog);
printf("Error linking program:\n%s\n", infoLog);
}
assert(0);
}
return program;
}
int main(int argc, char *argv[])
{
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);
GLuint vs = CompileShader(GL_VERTEX_SHADER,
"attribute vec4 pos;\n"
"varying vec2 pUv;\n"
"void main() { pUv = pos.xy; gl_Position = pos; }");
GLuint ps = CompileShader(GL_FRAGMENT_SHADER,
"precision lowp float;\n"
"layout(binding = 4) uniform sampler2D tex;\n"
"varying vec2 pUv;\n"
"void main() { gl_FragColor = texture2D(tex, pUv); }");
GLuint program = CreateProgram(vs, ps);
glUseProgram(program);
GLuint tex[2];
glGenTextures(2, tex);
glActiveTexture(GL_TEXTURE0 + 4);
glBindTexture(GL_TEXTURE_2D, tex[0]);
uint32_t color[4] = {
0xFF0000FF,
0xFF00FF00,
0xFFFF0000,
0xFFFFFFFF,
};
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, color);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glActiveTexture(GL_TEXTURE0 + 5);
glBindTexture(GL_TEXTURE_2D, tex[1]);
uint32_t color2[4] = {
0xFFFF0000,
0xFFFF00FF,
0xFF00FF00,
0xFF000000,
};
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, color2);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
static const float vb[] = {
-1.0f, -1.0f,
1.0f, -1.0f,
-1.0f, 1.0f,
-1.0f, 1.0f,
1.0f, -1.0f,
1.0f, 1.0f,
};
GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vb), vb, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 8, 0);
glEnableVertexAttribArray(0);
glClearColor(0.3f,0.3f,0.3f,1);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
uint8_t data[4];
glReadPixels(160, 85, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, data);
printf("output color: %u, %u, %u, %u\n", data[0], data[1], data[2], data[3]);
assert(data[0] == 255);
assert(data[1] == 0);
assert(data[2] == 0);
assert(data[3] == 255);
GLuint ps2 = CompileShader(GL_FRAGMENT_SHADER,
"precision lowp float;\n"
"layout(binding = 4) uniform sampler2D tex[2];\n"
"varying vec2 pUv;\n"
"void main() { gl_FragColor = texture2D(tex[0], pUv) + texture2D(tex[1], pUv); }");
GLuint program2 = CreateProgram(vs, ps2);
glUseProgram(program2);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
glReadPixels(160, 85, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, data);
printf("output 2 color: %u, %u, %u, %u\n", data[0], data[1], data[2], data[3]);
assert(data[0] == 255);
assert(data[1] == 0);
assert(data[2] == 255);
assert(data[3] == 255);
printf("Test passed!\n");
return 0;
}
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