src/client/shader.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <unistd.h>
   5 #include "client/shader.h"
   6
   7 static GLuint compile_shader(GLenum type, const char *path, const char *name, GLuint program, const char *definitions)
   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         // Minimum OpenGL version is 4.2.0 (idk some shader feature from that version is required)
  51         const char *version = "#version 420 core\n"; // 420 blaze it
  52
  53         const char *code_list[3] = {
  54                 version,
  55                 definitions,
  56                 code,
  57         };
  58
  59         int size_list[3] = {
  60                 18,
  61                 strlen(definitions),
  62                 size,
  63         };
  64
  65         glShaderSource(id, 3, code_list, size_list);
  66
  67         glCompileShader(id);
  68
  69         GLint success;
  70         glGetShaderiv(id, GL_COMPILE_STATUS, &success);
  71         if (!success) {
  72                 char errbuf[BUFSIZ];
  73                 glGetShaderInfoLog(id, BUFSIZ, NULL, errbuf);
  74                 fprintf(stderr, "[error] failed to compile %s shader: %s", name, errbuf);
  75                 glDeleteShader(id);
  76                 return 0;
  77         }
  78
  79         glAttachShader(program, id);
  80
  81         return id;
  82 }
  83
  84 bool shader_program_create(const char *path, GLuint *idptr, const char *definitions)
  85 {
  86         GLuint id = glCreateProgram();
  87
  88         if (!definitions)
  89                 definitions = "";
  90
  91         GLuint vert, frag;
  92
  93         if (!(vert = compile_shader(GL_VERTEX_SHADER, path, "vertex", id, definitions))) {
  94                 glDeleteProgram(id);
  95                 return false;
  96         }
  97
  98         if (!(frag = compile_shader(GL_FRAGMENT_SHADER, path, "fragment", id, definitions))) {
  99                 glDeleteShader(vert);
 100                 glDeleteProgram(id);
 101                 return false;
 102         }
 103
 104         glLinkProgram(id);
 105         glDeleteShader(vert);
 106         glDeleteShader(frag);
 107
 108         GLint success;
 109         glGetProgramiv(id, GL_LINK_STATUS, &success);
 110         if (!success) {
 111                 char errbuf[BUFSIZ];
 112                 glGetProgramInfoLog(id, BUFSIZ, NULL, errbuf);
 113                 fprintf(stderr, "[error] failed to link shader program: %s\n", errbuf);
 114                 glDeleteProgram(id);
 115                 return false;
 116         }
 117
 118         *idptr = id;
 119         return true;
 120 }