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;
  31
  32    version = (const char *) glGetString(GL_VERSION);
  33    if (version[0] != '2' || version[1] != '.') {
  34       printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
  35       return GL_FALSE;
  36    }
  37    return GL_TRUE;
  38 }
  39
  40
  41 GLuint
  42 CompileShaderText(GLenum shaderType, const char *text)
  43 {
  44    GLuint shader;
  45    GLint stat;
  46
  47    Init();
  48
  49    shader = glCreateShader_func(shaderType);
  50    glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
  51    glCompileShader_func(shader);
  52    glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
  53    if (!stat) {
  54       GLchar log[1000];
  55       GLsizei len;
  56       glGetShaderInfoLog_func(shader, 1000, &len, log);
  57       fprintf(stderr, "Error: problem compiling shader: %s\n", log);
  58       exit(1);
  59    }
  60    else {
  61       /*printf("Shader compiled OK\n");*/
  62    }
  63    return shader;
  64 }
  65
  66
  67 /**
  68  * Read a shader from a file.
  69  */
  70 GLuint
  71 CompileShaderFile(GLenum shaderType, const char *filename)
  72 {
  73    const int max = 100*1000;
  74    int n;
  75    char *buffer = (char*) malloc(max);
  76    GLuint shader;
  77
  78    FILE *f = fopen(filename, "r");
  79    if (!f) {
  80       return 0;
  81    }
  82
  83    n = fread(buffer, 1, max, f);
  84    /*printf("read %d bytes from shader file %s\n", n, filename);*/
  85    if (n > 0) {
  86       buffer[n] = 0;
  87       shader = CompileShaderText(shaderType, buffer);
  88    }
  89    else {
  90       return 0;
  91    }
  92
  93    fclose(f);
  94    free(buffer);
  95
  96    return shader;
  97 }
  98
  99
 100 GLuint
 101 LinkShaders(GLuint vertShader, GLuint fragShader)
 102 {
 103    GLuint program = glCreateProgram_func();
 104
 105    glAttachShader_func(program, fragShader);
 106    glAttachShader_func(program, vertShader);
 107    glLinkProgram_func(program);
 108
 109    /* check link */
 110    {
 111       GLint stat;
 112       glGetProgramiv_func(program, GL_LINK_STATUS, &stat);
 113       if (!stat) {
 114          GLchar log[1000];
 115          GLsizei len;
 116          glGetProgramInfoLog_func(program, 1000, &len, log);
 117          fprintf(stderr, "Shader link error:\n%s\n", log);
 118          return 0;
 119       }
 120    }
 121
 122    return program;
 123 }
 124
 125
 126 void
 127 InitUniforms(GLuint program, struct uniform_info uniforms[])
 128 {
 129    GLuint i;
 130
 131    for (i = 0; uniforms[i].name; i++) {
 132       uniforms[i].location
 133          = glGetUniformLocation_func(program, uniforms[i].name);
 134
 135       printf("Uniform %s location: %d\n", uniforms[i].name,
 136              uniforms[i].location);
 137
 138       switch (uniforms[i].size) {
 139       case 1:
 140          if (uniforms[i].type == GL_INT)
 141             glUniform1i_func(uniforms[i].location,
 142                              (GLint) uniforms[i].value[0]);
 143          else
 144             glUniform1fv_func(uniforms[i].location, 1, uniforms[i].value);
 145          break;
 146       case 2:
 147          glUniform2fv_func(uniforms[i].location, 1, uniforms[i].value);
 148          break;
 149       case 3:
 150          glUniform3fv_func(uniforms[i].location, 1, uniforms[i].value);
 151          break;
 152       case 4:
 153          glUniform4fv_func(uniforms[i].location, 1, uniforms[i].value);
 154          break;
 155       default:
 156          abort();
 157       }
 158    }
 159 }