glsl.cpp

/* -------------------------------------------------------- */
/* -------------------------------------------------------- */
/*

    TP OpenGL - Graphics and Sound Synthesis course

George Drettakis, Adrien Bousseau, Sylvain Lefebvre

mailto: FirstName.LastName@inria.fr

REVES / INRIA

History:
- Created 2006-10-10 (SL)
- Update 2013-02 (AB)

*/
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/*

Helper functions for GLSL

*/
/* -------------------------------------------------------- */

#include <stdlib.h>
#include <iostream>
#include "glsl.h"

#define	GLhandle GLuint

#define printOpenGLError() printOglError(__FILE__, __LINE__)

int printOglError(char *file, int line)
{

    GLenum glErr;
    int    retCode = 0;

    glErr = glGetError();
    if (glErr != GL_NO_ERROR)
    {
        printf("glError in file %s @ line %d: %s\n",
			     file, line, gluErrorString(glErr));
        retCode = 1;
    }
    return retCode;
}

#ifdef	_WIN32
GLuint 
#else
unsigned int
#endif
loadGLSLShader(const char *prg,GLuint type)
{
	
#ifdef _WIN32
	int id;
#else
	GLhandle id;
#endif
	printOpenGLError();
	// create shader object
	id = glCreateShader(type);
	printOpenGLError();
	// setup string as source
	glShaderSource(id,1,&prg,(const GLint*)NULL);
	// compile the shader
	glCompileShader(id);
	// check for errors
	printOpenGLError();
	GLint compiled;
	glGetShaderiv(id,GL_COMPILE_STATUS, &compiled);
	if (compiled != GL_TRUE) {
		// there was an error => display

		GLint maxLength;
		glGetShaderiv(id, GL_INFO_LOG_LENGTH, &maxLength);
		GLchar *infoLog=new GLchar[maxLength+1];
		glGetShaderInfoLog(id, maxLength, (GLsizei*)NULL, infoLog);
		fprintf(stderr,"\n\n****%s shader failed to compile ****\n%s",type==GL_VERTEX_SHADER ? "Vertex" : "Fragment",infoLog);
		delete [](infoLog);

		// exit on error
//		exit (0);
	}
	// done, return shader id
	return (id);
}

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/*
 createGLSLProgram
 
 Create a GLSL program and load shaders.
 
 * Inputs
 - vp_code   : null terminated string for vertex program
 - fp_code   : null terminated string for fragment program
 * Output
 - program GL id
 
 */
#ifdef	_WIN32
GLuint 
#else
unsigned int
#endif
createGLSLProgram(const char *vp_code,const char *fp_code)
{
	
	// create program
#ifdef _WIN32
	GLuint vp,fp;
	int id;
#else
	GLhandle vp,fp;
	GLhandle id;
#endif
//	id = glCreateProgramObjectARB();
printOpenGLError();
	id = glCreateProgram();
	// if vertex program code is given, compile it
	if (vp_code) {
		vp=loadGLSLShader(vp_code,GL_VERTEX_SHADER);
		glAttachShader(id,vp);
	}
	// if fragment program code is given, compile it
	if (fp_code) {
		fp=loadGLSLShader(fp_code,GL_FRAGMENT_SHADER);
		glAttachShader(id,fp);
	}
	// link compiled shaders
	glLinkProgram(id);
	// check link success
	GLint linked;
/*
	glGetObjectParameteriv(id,GL_OBJECT_LINK_STATUS_, &linked);
	if (!linked) {
		// there was an error => display
		GLint maxLength;
		glGetObjectParameteriv(id,GL_OBJECT_INFO_LOG_LENGTH_, &maxLength);
		GLchar *infoLog=new GLchar[maxLength+1];
		glGetInfoLog(id, maxLength, (GLsizei*)NULL, infoLog);
		fprintf(stderr,"\n\n**** GLSL program failed to link ****\n%s",infoLog);
		delete [](infoLog);
		// exit on error
		exit (0);
	}
*/
	// free compiled shaders (they are now embbeded into the program)
/*
	if (vp_code) {
		glDeleteObjectARB(vp);
	}
	if (fp_code) {
		glDeleteObjectARB(fp);
	}
*/
	// set as current program
	glUseProgram(id);
	// done, return program id
	return (id);
}
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/*
 Load a string from a file
 
 Returned string must be deleted with delete[]()
*/
const char *loadStringFromFile(const char *fname)
{
  // open file
  FILE *f=fopen(fname,"rb");
  if (f == NULL) {
	  fprintf(stderr,"[ERROR] Cannot open file '%s'\n",fname);
	  exit (-1);
  }
  // get file size
  fseek(f,0,SEEK_END);    // goto end
  long fsize = ftell(f);  // get size
  fseek(f,0,SEEK_SET);    // goto begining
  // allocate string
  char *str=new char[fsize+1];
  // read
  fread(str,fsize,sizeof(char),f);
  str[fsize]='\0';
  // close file
  fclose(f);
  // return string
  return (str);
}

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