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Necr0Potenc3

easy,fast resizing image to bypass "not a power of 2" problem [+contribution]

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here is the function that does it, I wrote it based on a microsoft article:
void ResizeImage(int Width, int Height, unsigned char *RGB, int *NewWidth, int *NewHeight, unsigned char **NewRGB, int MaxRes)
{
   GLint glMaxTexDim;
   double xPow2, yPow2;
   int ixPow2, iyPow2;
   int xSize2, ySize2;
   
   unsigned char *Data = NULL;

   glGetIntegerv(GL_MAX_TEXTURE_SIZE, &glMaxTexDim);
   if(glMaxTexDim > MaxRes) glMaxTexDim = MaxRes;

   if (Width <= glMaxTexDim)
      xPow2 = log((double)Width) / log(2.0);
   else
      xPow2 = log((double)glMaxTexDim) / log(2.0);

   if (Height <= glMaxTexDim)
      yPow2 = log((double)Height) / log(2.0);
   else
      yPow2 = log((double)glMaxTexDim) / log(2.0);

   ixPow2 = (int)xPow2;
   iyPow2 = (int)yPow2;

   if (xPow2 != (double)ixPow2)
      ixPow2++;
   if (yPow2 != (double)iyPow2)
      iyPow2++;

   xSize2 = 1 << ixPow2;
   ySize2 = 1 << iyPow2;

   Data = (unsigned char*)malloc(xSize2 * ySize2 * 3);
   
   gluScaleImage(GL_RGB, Width, Height, GL_UNSIGNED_BYTE, RGB, xSize2, ySize2, GL_UNSIGNED_BYTE, Data);
   
   *NewRGB = Data;
   *NewWidth = xSize2 ;
   *NewHeight = ySize2 ;
    
    return;     
}
its pretty much plug and play. Width, Height and RGB are the "in" parameters. RGB is a buffer with RGB data. NewWidth, NewHeight and NewRGB are "out" parameters, all of them pointers to the variables where the info will be dumped. NewRGB is actually allocated by the function so you have to take care of freeing the memory once you're done with it "ermm... ok. so how do I use it?" just a sample:
static void GenTextures(void)
{
    int bmWidth = 0, bmHeight = 0, error = 0;
    unsigned char *Data = NULL;
    
    unsigned int newWidth = 0, newHeight = 0;
    unsigned char *newData = NULL;
    
    error = LoadBMP("background.bmp", &bmWidth, &bmHeight, &Data);
    if(error)
    {
        sprintf(ErrorTxt, "Could not load background.bmp error: %d", error);
        return;
    }
    
    ResizeImage(bmWidth, bmHeight, Data, &newWidth, &newHeight, &newData, 800);
    
    glGenTextures(1, &texture[0]);
    glBindTexture(GL_TEXTURE_2D, texture[0]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, 3, newWidth, newHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, newData);
    
    free(Data);
    free(newData);
    
       
    return;
}
hope it helps -gR

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