shader utility functions

progs/util/shaderutil.c

@@ -0,0 +1,159 @@
+/**
+ * Utilities for OpenGL shading language
+ *
+ * Brian Paul
+ * 9 April 2008
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <GL/glut.h>
+#include "extfuncs.h"
+#include "shaderutil.h"
+
+
+static void
+Init(void)
+{
+   static GLboolean firstCall = GL_TRUE;
+   if (firstCall) {
+      GetExtensionFuncs();
+      firstCall = GL_FALSE;
+   }
+}
+
+
+GLboolean
+ShadersSupported(void)
+{
+   const char *version;
+
+   version = (const char *) glGetString(GL_VERSION);
+   if (version[0] != '2' || version[1] != '.') {
+      printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
+      return GL_FALSE;
+   }
+   return GL_TRUE;
+}
+
+
+GLuint
+CompileShaderText(GLenum shaderType, const char *text)
+{
+   GLuint shader;
+   GLint stat;
+
+   Init();
+
+   shader = glCreateShader_func(shaderType);
+   glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
+   glCompileShader_func(shader);
+   glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
+   if (!stat) {
+      GLchar log[1000];
+      GLsizei len;
+      glGetShaderInfoLog_func(shader, 1000, &len, log);
+      fprintf(stderr, "Error: problem compiling shader: %s\n", log);
+      exit(1);
+   }
+   else {
+      /*printf("Shader compiled OK\n");*/
+   }
+   return shader;
+}
+
+
+/**
+ * Read a shader from a file.
+ */
+GLuint
+CompileShaderFile(GLenum shaderType, const char *filename)
+{
+   const int max = 100*1000;
+   int n;
+   char *buffer = (char*) malloc(max);
+   GLuint shader;
+
+   FILE *f = fopen(filename, "r");
+   if (!f) {
+      return 0;
+   }
+
+   n = fread(buffer, 1, max, f);
+   /*printf("read %d bytes from shader file %s\n", n, filename);*/
+   if (n > 0) {
+      buffer[n] = 0;
+      shader = CompileShaderText(shaderType, buffer);
+   }
+   else {
+      return 0;
+   }
+
+   fclose(f);
+   free(buffer);
+
+   return shader;
+}
+
+
+GLuint
+LinkShaders(GLuint vertShader, GLuint fragShader)
+{
+   GLuint program = glCreateProgram_func();
+
+   glAttachShader_func(program, fragShader);
+   glAttachShader_func(program, vertShader);
+   glLinkProgram_func(program);
+
+   /* check link */
+   {
+      GLint stat;
+      glGetProgramiv_func(program, GL_LINK_STATUS, &stat);
+      if (!stat) {
+         GLchar log[1000];
+         GLsizei len;
+         glGetProgramInfoLog_func(program, 1000, &len, log);
+         fprintf(stderr, "Shader link error:\n%s\n", log);
+         return 0;
+      }
+   }
+
+   return program;
+}
+
+
+void
+InitUniforms(GLuint program, struct uniform_info uniforms[])
+{
+   GLuint i;
+
+   for (i = 0; uniforms[i].name; i++) {
+      uniforms[i].location
+         = glGetUniformLocation_func(program, uniforms[i].name);
+
+      printf("Uniform %s location: %d\n", uniforms[i].name,
+             uniforms[i].location);
+
+      switch (uniforms[i].size) {
+      case 1:
+         if (uniforms[i].type == GL_INT)
+            glUniform1i_func(uniforms[i].location,
+                             (GLint) uniforms[i].value[0]);
+         else
+            glUniform1fv_func(uniforms[i].location, 1, uniforms[i].value);
+         break;
+      case 2:
+         glUniform2fv_func(uniforms[i].location, 1, uniforms[i].value);
+         break;
+      case 3:
+         glUniform3fv_func(uniforms[i].location, 1, uniforms[i].value);
+         break;
+      case 4:
+         glUniform4fv_func(uniforms[i].location, 1, uniforms[i].value);
+         break;
+      default:
+         abort();
+      }
+   }
+}

progs/util/shaderutil.h

@@ -0,0 +1,34 @@
+#ifndef SHADER_UTIL_H
+#define SHADER_UTIL_H
+
+
+
+struct uniform_info
+{
+   const char *name;
+   GLuint size;
+   GLenum type;  /**< GL_FLOAT or GL_INT */
+   GLfloat value[4];
+   GLint location;  /**< filled in by InitUniforms() */
+};
+
+#define END_OF_UNIFORMS   { NULL, 0, GL_NONE, { 0, 0, 0, 0 }, -1 }
+
+
+extern GLboolean
+ShadersSupported(void);
+
+extern GLuint
+CompileShaderText(GLenum shaderType, const char *text);
+
+extern GLuint
+CompileShaderFile(GLenum shaderType, const char *filename);
+
+extern GLuint
+LinkShaders(GLuint vertShader, GLuint fragShader);
+
+extern void
+InitUniforms(GLuint program, struct uniform_info uniforms[]);
+
+
+#endif /* SHADER_UTIL_H */