source: orxonox.OLD/branches/guidedmissile/src/lib/graphics/importer/texture.cc @ 5763

/*
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Benjamin Grauer
   co-programmer: ...
*/

#define DEBUG_SPECIAL_MODULE DEBUG_MODULE_IMPORTER

#include "texture.h"

#include "debug.h"
#include "graphics_engine.h"

#ifdef HAVE_SDL_IMAGE_H
#include <SDL_image.h>
#else
#include <SDL/SDL_image.h>
#endif

/**
 *  Constructor for a Texture
*/
Texture::Texture(const char* imageName)
{
  this->setClassID(CL_TEXTURE, "Texture");
  this->setName(imageName);

  this->bAlpha = false;
  this->texture = 0;
  this->image = NULL;

  if (imageName != NULL)
    this->loadImage(imageName);
}

/**
 *  Destructor of a Texture

   Frees Data, and deletes the textures from GL
*/
Texture::~Texture()
{
  if (this->texture != 0)
    glDeleteTextures(1, &this->texture);
  if (this->image != NULL)
    SDL_FreeSurface(this->image);
}


/**
 *  loads an Image from a file to a Texture
 * @param imageName The image to load
*/
bool Texture::loadImage(const char* imageName)
{
  if (GraphicsEngine::texturesEnabled)
    {
      if (this->image != NULL)
        {
          SDL_FreeSurface(this->image);
          this->image = NULL;
        }
      if (this->texture != 0)
        {
          glDeleteTextures(1, &this->texture);
          this->texture = 0;
        }
      if (imageName != NULL)
        {
          SDL_Surface* tmpSurf;
          if (this->texture)
            glDeleteTextures(1, &this->texture);
          // load the new Image to memory
          tmpSurf = IMG_Load(imageName);
          if(tmpSurf != NULL)
          {
            PRINTF(4)("loading Image %s\n", imageName);
            this->image = this->prepareSurface(tmpSurf);
            this->texture = loadTexToGL(this->image);
            SDL_FreeSurface(tmpSurf);
            return true;
          }
          else
            {
              PRINTF(1)("IMG_Load: %s\n", IMG_GetError());
              this->texture = 0;
              return false;
            }
        }
      else
        {
          PRINTF(2)("Image-Name not specified\n");
          return false;
        }
    }
  return false;
}

bool Texture::rebuild()
{
  if (this->texture != 0)
    {
      glDeleteTextures(1,&this->texture);
      this->texture = 0;
    }

  if (this->image != NULL)
    {
      PRINTF(4)("Reloading Texture %s\n", this->getName());
      this->texture = this->loadTexToGL(this->image);
    }
  
}

/**
 * converts surface to a new SDL_Surface, that is loadable by openGL
 * @param surface the Surface to convert
 * @returns a !!new!! Surface, that is loadable by openGL.
 */
SDL_Surface* Texture::prepareSurface(SDL_Surface* surface)
{
  PRINTF(4)("Loading texture to OpenGL-Environment.\n");
  
  SDL_Surface *image;
  SDL_Rect area;
  Uint32 saved_flags;
  Uint8  saved_alpha;
  
  image = SDL_CreateRGBSurface(SDL_SWSURFACE,
                               surface->w, surface->h,
                               32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */
                               0x000000FF,
                               0x0000FF00,
                               0x00FF0000,
                               0xFF000000
#else
                               0xFF000000,
                               0x00FF0000,
                               0x0000FF00,
                               0x000000FF
#endif
                               );
  if ( image == NULL )
    return NULL;
  
  /* Save the alpha blending attributes */
  saved_flags = surface->flags&(SDL_SRCALPHA|SDL_RLEACCELOK);
  saved_alpha = surface->format->alpha;
  if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
    SDL_SetAlpha(surface, 0, 0);
  }
  
  /* Copy the surface into the GL texture image */
  area.x = 0;
  area.y = 0;
  area.w = surface->w;
  area.h = surface->h;
  SDL_BlitSurface(surface, &area, image, &area);
  
  /* Restore the alpha blending attributes */
  if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) 
    {
      SDL_SetAlpha(surface, saved_flags | SDL_OPENGL, saved_alpha);
      this->bAlpha = true;
    }
  return image;
}


/**
 *  Loads a Texture to the openGL-environment.
 * @param surface the Image to load to openGL
 * @returns The ID of the texture.
 */
GLuint Texture::loadTexToGL (SDL_Surface* surface) const
{
  GLuint texture = 0;
  /* Create an OpenGL texture for the image */
  glGenTextures(1, &texture);
  glBindTexture(GL_TEXTURE_2D, texture);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  // build the Texture
  glTexImage2D(GL_TEXTURE_2D,
               0,
               GL_RGBA,
               surface->w, surface->h,
               0,
               GL_RGBA,
               GL_UNSIGNED_BYTE,
               surface->pixels);
  // build the MipMaps
  gluBuild2DMipmaps(GL_TEXTURE_2D,
                    GL_RGBA,
                    surface->w,
                    surface->h,
                    GL_RGBA,
                    GL_UNSIGNED_BYTE,
                    surface->pixels);
  glBindTexture(GL_TEXTURE_2D, 0);
  return texture;
}