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