GetMemRequired

int GetMemRequired( int width, int height, ImageFormat imageFormat, bool mipmap )
{
    if( !mipmap )
    {
        if( imageFormat == IMAGE_FORMAT_DXT1 ||
            imageFormat == IMAGE_FORMAT_DXT3 ||
            imageFormat == IMAGE_FORMAT_DXT5 )
        {
/*
            DDSURFACEDESC desc;
            memset( &desc, 0, sizeof(desc) );

            DWORD dwEncodeType;
            dwEncodeType = GetDXTCEncodeType( imageFormat );
            desc.dwSize = sizeof( desc );
            desc.dwFlags = DDSD_WIDTH | DDSD_HEIGHT;
            desc.dwWidth = width;
            desc.dwHeight = height;
            return S3TCgetEncodeSize( &desc, dwEncodeType );
*/
            Assert( ( width < 4 ) || !( width % 4 ) );
            Assert( ( height < 4 ) || !( height % 4 ) );
            if( width < 4 && width > 0 )
            {
                width = 4;
            }
            if( height < 4 && height > 0 )
            {
                height = 4;
            }
            int numBlocks = ( width * height ) >> 4;
            switch( imageFormat )
            {
            case IMAGE_FORMAT_DXT1:
                return numBlocks * 8;
                break;
            case IMAGE_FORMAT_DXT3:
            case IMAGE_FORMAT_DXT5:
                return numBlocks * 16;
                break;
            default:
                Assert( 0 );
                return 0;
                break;
            }
        }
        else
        {
            return width * height * SizeInBytes(imageFormat);
        }
    }
    else
    {
        int memSize = 0;

        while( 1 )
        {
            memSize += GetMemRequired( width, height, imageFormat, false );
            if( width == 1 && height == 1 )
            {
                break;
            }
            width >>= 1;
            height >>= 1;
            if( width < 1 )
            {
                width = 1;
            }
            if( height < 1 )
            {
                height = 1;
            }
        }

        return memSize;
    }
}