src/shaders.c

   1 #include <string.h>
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5 #include "shaders.h"
   6
   7 static GLuint compile_and_attach_shader(GLenum type, const char *path, const char *name, GLuint program)
   8 {
   9         char full_path[strlen(path) + 1 + strlen(name) + 1 + 4 + 1];
  10         sprintf(full_path, "%s/%s.glsl", path, name);
  11
  12         FILE *file = fopen(full_path, "r");
  13         if (! file) {
  14                 perror("fopen");
  15                 return 0;
  16         }
  17
  18         if (fseek(file, 0, SEEK_END) == -1) {
  19                 perror("fseek");
  20                 fclose(file);
  21                 return 0;
  22         }
  23
  24         long size = ftell(file);
  25
  26         if (size == 1) {
  27                 perror("ftell");
  28                 fclose(file);
  29                 return 0;
  30         }
  31
  32         if (fseek(file, 0, SEEK_SET) == -1) {
  33                 perror("fseek");
  34                 fclose(file);
  35                 return 0;
  36         }
  37
  38         char code[size];
  39
  40         if (fread(code, 1, size, file) != (size_t) size) {
  41                 perror("fread");
  42                 fclose(file);
  43                 return 0;
  44         }
  45
  46         fclose(file);
  47
  48         GLuint id = glCreateShader(type);
  49
  50         char const *codeptr = code;
  51         const int isize = (int) size;
  52         glShaderSource(id, 1, &codeptr, &isize);
  53
  54         glCompileShader(id);
  55
  56         GLint success;
  57         glGetShaderiv(id, GL_COMPILE_STATUS, &success);
  58         if (! success) {
  59                 char errbuf[BUFSIZ];
  60                 glGetShaderInfoLog(id, BUFSIZ, NULL, errbuf);
  61                 fprintf(stderr, "Failed to compile %s shader: %s\n", name, errbuf);
  62                 glDeleteShader(id);
  63                 return 0;
  64         }
  65
  66         glAttachShader(program, id);
  67
  68         return id;
  69 }
  70
  71
  72 ShaderProgram *create_shader_program(const char *path)
  73 {
  74         GLuint id = glCreateProgram();
  75
  76         GLuint vert, frag;
  77
  78         if (! (vert = compile_and_attach_shader(GL_VERTEX_SHADER, path, "vertex", id))) {
  79                 glDeleteProgram(id);
  80                 return NULL;
  81         }
  82
  83         if (! (frag = compile_and_attach_shader(GL_FRAGMENT_SHADER, path, "fragment", id))) {
  84                 glDeleteShader(vert);
  85                 glDeleteProgram(id);
  86                 return NULL;
  87         }
  88
  89         glLinkProgram(id);
  90         glDeleteShader(vert);
  91         glDeleteShader(frag);
  92
  93         GLint success;
  94         glGetProgramiv(id, GL_LINK_STATUS, &success);
  95         if (! success) {
  96                 char errbuf[BUFSIZ];
  97                 glGetProgramInfoLog(id, BUFSIZ, NULL, errbuf);
  98                 fprintf(stderr, "Failed to link shader program: %s\n", errbuf);
  99                 glDeleteProgram(id);
 100                 return NULL;
 101         }
 102
 103         ShaderProgram *prog = malloc(sizeof(ShaderProgram));
 104         prog->id = id;
 105         prog->loc_model = glGetUniformLocation(id, "model");
 106         prog->loc_view = glGetUniformLocation(id, "view");
 107         prog->loc_projection = glGetUniformLocation(id, "projection");
 108
 109         return prog;
 110 }
 111
 112 void delete_shader_program(ShaderProgram *prog)
 113 {
 114         glDeleteProgram(prog->id);
 115         free(prog);
 116 }
 117