Attachment 107340 Details for Bug 84677 – main.c demonstrating the issue

main.c demonstrating the issue

main.c (text/plain), 2.90 KB, created by Ben Foppa on 2014-10-05 00:46:53 UTC

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Creator: Ben Foppa

Created: 2014-10-05 00:46:53 UTC

Size: 2.90 KB

patch

obsolete

>#include <stdio.h>
>#include <stdlib.h>
>#include <GL/gl.h>
>#include <SDL2/SDL.h>
>
>void compile_and_attach(GLuint program, GLenum ty, const char* path) {
>  GLuint shader = glCreateShader(ty);
>  char* content;
>  {
>    FILE* file = fopen(path, "r");
>    long len;
>    fseek (file , 0 , SEEK_END);
>    len = ftell (file);
>    rewind (file);
>
>    content = (char*) malloc (sizeof(char)*(len + 1));
>    content[len] = 0;
>    if (content == NULL) { fputs ("Memory error",stderr); exit (2); }
>
>    size_t result = fread (content,1,len,file);
>    if (result != len) {fputs ("Reading error",stderr); exit (3);}
>    fclose(file);
>  }
>
>  // Attempt to compile the shader
>  glShaderSource(shader, 1, &content, NULL);
>  glCompileShader(shader);
>
>  // Get the compile status
>  GLint status;
>  glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
>
>  if (status != GL_TRUE ){
>    fprintf(stderr, "error compiling shader\n");
>    exit(4);
>  }
>  glAttachShader(program, shader);
>}
>
>void link_shader(GLuint program) {
>  glLinkProgram(program);
>
>  // Get the link status
>  GLint status;
>  glGetProgramiv(program, GL_LINK_STATUS, &status);
>
>  if (status != GL_TRUE) {
>    fputs("failed to link shader", stderr);
>    exit(5);
>  };
>}
>
>int main() {
>  SDL_Window *mainwindow; /* Our window handle */
>  SDL_GLContext maincontext; /* Our opengl context handle */
>
>  if (SDL_Init(SDL_INIT_VIDEO) < 0) {
>    fputs("init failed", stderr);
>    exit(6);
>  }
>
>  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
>  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
>
>  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
>  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
>
>  /* Create our window centered at 512x512 resolution */
>  mainwindow = SDL_CreateWindow("shadertest", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
>      800, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
>  if (!mainwindow) {
>    fputs("Unable to create window", stderr);
>    exit(7);
>  }
>
>  /* Create our opengl context and attach it to our window */
>  maincontext = SDL_GL_CreateContext(mainwindow);
>
>  if (!maincontext) {
>    fputs("Unable to create context", stderr);
>    exit(8);
>  }
>
>  GLuint texture_shader = glCreateProgram();
>  compile_and_attach(texture_shader, GL_VERTEX_SHADER, "shaders/line.vert");
>  compile_and_attach(texture_shader, GL_FRAGMENT_SHADER, "shaders/line.frag");
>  link_shader(texture_shader);
>
>  GLuint empty_array;
>  glGenVertexArrays(1, &empty_array);
>
>  glBindVertexArray(empty_array);
>
>  if(glGetError() != GL_NO_ERROR) {
>    fputs("OpenGL error in loading", stderr);
>    exit(6);
>  }
>
>  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
>  glEnable(GL_LINE_SMOOTH);
>  glLineWidth(2.5); 
>
>  for(;;) {
>    SDL_Event event;
>    while (SDL_PollEvent(&event))
>    {
>      if (event.type == SDL_QUIT) {
>        exit(0);
>      }
>    }
>
>    glClear(GL_COLOR_BUFFER_BIT);
>
>    glUseProgram(texture_shader);
>    glDrawArrays(GL_TRIANGLES, 0, 3);
>
>    SDL_GL_SwapWindow(mainwindow);
>
>    glFlush();
>    glFinish();
>  }
>}

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