/// <summary>
/// Given a bitmap (GDI+), create for it an OpenGL texture and return its ID
/// </summary>
/// <param name="bitmap"></param>
/// <returns>the OGL texture id</returns>
/// <remarks>in order to allow hardware acceleration, texture size must be power of two.</remarks>
private uint CreateTexture(Bitmap bitmap)
{
try
{
//get the bitmap's dimensions
int h = bitmap.Height;
int w = bitmap.Width;
int s = Math.Max(h, w);
//calculate the closest power of two to match the bitmap's size
//(thank god for high-school math...)
double x = Math.Log(Convert.ToDouble(s)) / Math.Log(2.0);
s = Convert.ToInt32(Math.Pow(2.0, Convert.ToDouble(Math.Ceiling(x))));
int bufferSizeInPixels = s * s;
//get the bitmap's raw data
Rectangle rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
bitmap.RotateFlip(RotateFlipType.RotateNoneFlipY);
System.Drawing.Imaging.BitmapData bitmapData;
bitmapData = bitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
byte[] bgrBuffer = new byte[bufferSizeInPixels * 3];
//scale the bitmap to be a power of two
unsafe
{
fixed(byte *pBgrBuffer = bgrBuffer)
{
GLU.gluScaleImage(GL.GL_BGR_EXT, bitmap.Size.Width, bitmap.Size.Height, GL.GL_UNSIGNED_BYTE, bitmapData.Scan0.ToPointer(), s, s, GL.GL_UNSIGNED_BYTE, pBgrBuffer);
}
}
//create a new buffer to store the raw data and set the transparency color (alpha = 0)
byte[] bgraBuffer = new byte[bufferSizeInPixels * 4];
int posBgr = 0;
int posBgra = 0;
for (int i = 0; i < bufferSizeInPixels; i++)
{
bgraBuffer[posBgra] = bgrBuffer[posBgr]; //B
bgraBuffer[posBgra + 1] = bgrBuffer[posBgr + 1]; //G
bgraBuffer[posBgra + 2] = bgrBuffer[posBgr + 2]; //R
//take care of the alpha
if (255 == bgrBuffer[posBgr] && 255 == bgrBuffer[posBgr + 1] && 255 == bgrBuffer[posBgr + 2])
{
bgraBuffer[posBgra + 3] = 0;
}
else
{
bgraBuffer[posBgra + 3] = 255;
}
posBgr += 3;
posBgra += 4;
}
//create the texture
uint[] texture = new uint[1];
GL.glEnable(GL.GL_TEXTURE_2D);
GL.glGenTextures(1, texture);
GL.glBindTexture(GL.GL_TEXTURE_2D, texture[0]);
//set the texture parameters
GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, (int)GL.GL_LINEAR);
GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MIN_FILTER, (int)GL.GL_LINEAR);
GL.glTexEnvi(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE, (int)GL.GL_MODULATE);
unsafe
{
fixed(byte *pBgraBuffer = bgraBuffer)
{
GL.glTexImage2D(GL.GL_TEXTURE_2D, 0, (int)GL.GL_RGBA, s, s, 0, GL.GL_BGRA_EXT, GL.GL_UNSIGNED_BYTE, pBgraBuffer);
}
}
//unlock the bitmap from memory
bitmap.UnlockBits(bitmapData);
//return the newly created texture id
return(texture[0]);
}
catch (Exception ex)
{
System.Diagnostics.Trace.WriteLine(ex.Message);
}
return((uint)0);
}
