texture_manager.cc

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/*
 *  texture_manager.cc
 *  Stage
 *
 *  Created by Alex Couture-Beil on 03/06/08.
 *  $Id$
 */

#include <sstream>
#include "texture_manager.hh"
#include "file_manager.hh"
using namespace Stg;

GLuint TextureManager::loadTexture( const char *filename )
{
//    if( filename == NULL )
  //      return 0;
    
        GLuint texName;
        Fl_Shared_Image *img = Fl_Shared_Image::get( filename );

        if( img == NULL) {
                fprintf( stderr, "unable to open image: %s\n", filename );
                //exit(-1);
                return 0;
        }
        
        //TODO display an error for incorrect depths
        if( img->d() != 3 && img->d() != 4 ) {
                fprintf( stderr, "unable to open image: %s - incorrect depth - should be 3 or 4\n", filename );
                return 0;
        }
        
        //TODO check for correct width/height - or convert it.
        
        uint8_t* pixels = (uint8_t*)(img->data()[0]);
        
        //vertically flip the image
        int img_size = img->w() * img->h() * img->d();
        uint8_t* img_flip = new uint8_t[ img_size ];
        
        const int row_width = img->w() * img->d();
        for( int i = 0; i < img->h(); i++ )
        memcpy( img_flip + ( i * row_width ), pixels + ( ( img->h() - i - 1) * row_width ), row_width );
        
        
        //create room for texture
        glGenTextures(1, &texName);
        
        glBindTexture(GL_TEXTURE_2D, texName);
        
        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
        
        glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        
        glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        
        //glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); //or use GL_DECAL or GL_MODULATE instead of DECAL to mix colours and textures
        
        gluBuild2DMipmaps (GL_TEXTURE_2D, img->d(), img->w(), img->h(), ( img->d() == 3 ? GL_RGB : GL_RGBA ), 
                                           GL_UNSIGNED_BYTE, img_flip );        
        
        glBindTexture( GL_TEXTURE_2D, 0 );
        return texName;
        }