progs/util/shaderutil.c

   1 /**
   2  * Utilities for OpenGL shading language
   3  *
   4  * Brian Paul
   5  * 9 April 2008
   6  */
   7
   8
   9 #include <assert.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <GL/glew.h>
  13 #include <GL/glut.h>
  14 #include "extfuncs.h"
  15 #include "shaderutil.h"
  16
  17
  18 static void
  19 Init(void)
  20 {
  21    static GLboolean firstCall = GL_TRUE;
  22    if (firstCall) {
  23       GetExtensionFuncs();
  24       firstCall = GL_FALSE;
  25    }
  26 }
  27
  28
  29 GLboolean
  30 ShadersSupported(void)
  31 {
  32    const char *version = (const char *) glGetString(GL_VERSION);
  33    if (version[0] == '2' && version[1] == '.') {
  34       return GL_TRUE;
  35    }
  36    else if (glutExtensionSupported("GL_ARB_vertex_shader")
  37             && glutExtensionSupported("GL_ARB_fragment_shader")
  38             && glutExtensionSupported("GL_ARB_shader_objects")) {
  39       fprintf(stderr, "Warning: Trying ARB GLSL instead of OpenGL 2.x.  This may not work.\n");
  40       return GL_TRUE;
  41    }
  42    return GL_TRUE;
  43 }
  44
  45
  46 GLuint
  47 CompileShaderText(GLenum shaderType, const char *text)
  48 {
  49    GLuint shader;
  50    GLint stat;
  51
  52    Init();
  53
  54    shader = glCreateShader_func(shaderType);
  55    glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
  56    glCompileShader_func(shader);
  57    glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
  58    if (!stat) {
  59       GLchar log[1000];
  60       GLsizei len;
  61       glGetShaderInfoLog_func(shader, 1000, &len, log);
  62       fprintf(stderr, "Error: problem compiling shader: %s\n", log);
  63       exit(1);
  64    }
  65    else {
  66       /*printf("Shader compiled OK\n");*/
  67    }
  68    return shader;
  69 }
  70
  71
  72 /**
  73  * Read a shader from a file.
  74  */
  75 GLuint
  76 CompileShaderFile(GLenum shaderType, const char *filename)
  77 {
  78    const int max = 100*1000;
  79    int n;
  80    char *buffer = (char*) malloc(max);
  81    GLuint shader;
  82    FILE *f;
  83
  84    Init();
  85
  86
  87    f = fopen(filename, "r");
  88    if (!f) {
  89       fprintf(stderr, "Unable to open shader file %s\n", filename);
  90       return 0;
  91    }
  92
  93    n = fread(buffer, 1, max, f);
  94    /*printf("read %d bytes from shader file %s\n", n, filename);*/
  95    if (n > 0) {
  96       buffer[n] = 0;
  97       shader = CompileShaderText(shaderType, buffer);
  98    }
  99    else {
 100       return 0;
 101    }
 102
 103    fclose(f);
 104    free(buffer);
 105
 106    return shader;
 107 }
 108
 109
 110 GLuint
 111 LinkShaders(GLuint vertShader, GLuint fragShader)
 112 {
 113    GLuint program = glCreateProgram_func();
 114
 115    assert(vertShader || fragShader);
 116
 117    if (fragShader)
 118       glAttachShader_func(program, fragShader);
 119    if (vertShader)
 120       glAttachShader_func(program, vertShader);
 121    glLinkProgram_func(program);
 122
 123    /* check link */
 124    {
 125       GLint stat;
 126       glGetProgramiv_func(program, GL_LINK_STATUS, &stat);
 127       if (!stat) {
 128          GLchar log[1000];
 129          GLsizei len;
 130          glGetProgramInfoLog_func(program, 1000, &len, log);
 131          fprintf(stderr, "Shader link error:\n%s\n", log);
 132          return 0;
 133       }
 134    }
 135
 136    return program;
 137 }
 138
 139
 140 void
 141 InitUniforms(GLuint program, struct uniform_info uniforms[])
 142 {
 143    GLuint i;
 144
 145    for (i = 0; uniforms[i].name; i++) {
 146       uniforms[i].location
 147          = glGetUniformLocation_func(program, uniforms[i].name);
 148
 149       printf("Uniform %s location: %d\n", uniforms[i].name,
 150              uniforms[i].location);
 151
 152       switch (uniforms[i].size) {
 153       case 1:
 154          if (uniforms[i].type == GL_INT)
 155             glUniform1i_func(uniforms[i].location,
 156                              (GLint) uniforms[i].value[0]);
 157          else
 158             glUniform1fv_func(uniforms[i].location, 1, uniforms[i].value);
 159          break;
 160       case 2:
 161          glUniform2fv_func(uniforms[i].location, 1, uniforms[i].value);
 162          break;
 163       case 3:
 164          glUniform3fv_func(uniforms[i].location, 1, uniforms[i].value);
 165          break;
 166       case 4:
 167          glUniform4fv_func(uniforms[i].location, 1, uniforms[i].value);
 168          break;
 169       default:
 170          abort();
 171       }
 172    }
 173 }