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// Copyright 2014 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 <emscripten.h>
#include <string.h>
#include <emscripten/html5.h>
#include <GLES2/gl2.h>
#include <math.h>
#include <assert.h>
#include <stdlib.h>
GLuint program;
#define PIX_C(x, y) ((x)/256.0f + (y)/256.0f)
#define CLAMP(c) ((c) < 0.f ? 0.f : ((c) > 1.f ? 1.f : (c)))
#define PIX(x, y) CLAMP(PIX_C(x, y))
void draw()
{
int w, h;
emscripten_get_canvas_element_size("#canvas", &w, &h);
float xs = (float)h / w;
float ys = 1.0f;
float mat[] = { xs, 0, 0, 0, 0, ys, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
glUniformMatrix4fv(glGetUniformLocation(program, "mat"), 1, 0, mat);
glClearColor(0,0,1,1);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
unsigned char* imageData = (unsigned char*)malloc(256*256*4*sizeof(unsigned char));
glReadPixels(0, 0, 256, 256, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
for(int y = 0; y < 256; ++y)
for(int x = 0; x < 256; ++x)
{
unsigned char red = imageData[(y*256+x)*4];
float expectedRed = PIX(x, y);
unsigned char eRed = (unsigned char)(expectedRed * 255.0f);
assert(abs((int)eRed - red) <= 2);
}
emscripten_cancel_main_loop();
printf("Test successful!\n");
#if _REENTRANT
// In PROXY_TO_PTHREAD mode its currently not enough to cancel the main
// loop and have the application exit:
// https://github.com/emscripten-core/emscripten/issues/18773
exit(0);
#endif
}
int main()
{
emscripten_set_canvas_element_size("#canvas", 256, 256);
EmscriptenWebGLContextAttributes attr;
emscripten_webgl_init_context_attributes(&attr);
attr.alpha = attr.depth = attr.stencil = attr.antialias = attr.preserveDrawingBuffer = attr.failIfMajorPerformanceCaveat = 0;
attr.enableExtensionsByDefault = 1;
attr.premultipliedAlpha = 0;
attr.majorVersion = 1;
attr.minorVersion = 0;
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE ctx = emscripten_webgl_create_context("#canvas", &attr);
emscripten_webgl_make_context_current(ctx);
GLuint vs = glCreateShader(GL_VERTEX_SHADER);
assert(vs);
const char *vss = "attribute vec4 vPosition; uniform mat4 mat; varying vec2 texCoord; void main() { gl_Position = vPosition; texCoord = (vPosition.xy + vec2(1.0)) * vec2(0.5); }";
glShaderSource(vs, 1, &vss, 0);
glCompileShader(vs);
GLint isCompiled = 0;
glGetShaderiv(vs, GL_COMPILE_STATUS, &isCompiled);
if (!isCompiled)
{
GLint maxLength = 0;
glGetShaderiv(vs, GL_INFO_LOG_LENGTH, &maxLength);
char *buf = malloc(maxLength);
glGetShaderInfoLog(vs, maxLength, &maxLength, buf);
printf("%s\n", buf);
return 1;
}
GLuint ps = glCreateShader(GL_FRAGMENT_SHADER);
const char *pss = "precision lowp float; varying vec2 texCoord; uniform vec3 colors[3]; uniform sampler2D tex; void main() { gl_FragColor = texture2D(tex, texCoord); }";
glShaderSource(ps, 1, &pss, 0);
glCompileShader(ps);
glGetShaderiv(ps, GL_COMPILE_STATUS, &isCompiled);
if (!isCompiled)
{
GLint maxLength = 0;
glGetShaderiv(ps, GL_INFO_LOG_LENGTH, &maxLength);
char *buf = malloc(maxLength);
glGetShaderInfoLog(ps, maxLength, &maxLength, buf);
printf("%s\n", buf);
return 1;
}
program = glCreateProgram();
assert(program);
glAttachShader(program, vs);
glAttachShader(program, ps);
glBindAttribLocation(program, 0, "vPosition");
glLinkProgram(program);
glGetProgramiv(program, GL_LINK_STATUS, &isCompiled);
if (!isCompiled)
{
GLint maxLength = 0;
glGetShaderiv(program, GL_INFO_LOG_LENGTH, &maxLength);
char *buf = malloc(maxLength);
glGetProgramInfoLog(program, maxLength, &maxLength, buf);
printf("%s\n", buf);
return 1;
}
glUseProgram(program);
GLuint vbo;
glGenBuffers(1, &vbo);
assert(vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
float verts[] = { -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1 };
glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, 0, sizeof(float)*2, 0);
glEnableVertexAttribArray(0);
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
float* texData = (float*)malloc(256*256*sizeof(float));
for(int y = 0; y < 256; ++y)
for(int x = 0; x < 256; ++x)
{
texData[y*256+x] = PIX(x, y);
}
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 256, 256, 0, GL_LUMINANCE, GL_FLOAT, texData);
emscripten_set_main_loop(draw, 0, 0);
return 0;
}
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