progs/util/shaderutil.c

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