public static Texture2D FixAlpha(Texture2D file)
{
RenderTarget2D result = null;
//Setup a render target to hold our final texture which will have premulitplied alpha values
result = new RenderTarget2D(CakeEngine.staticDevice, file.Width, file.Height);
RenderManager.SetTarget(result);
RenderManager.ClearTarget(Color.Black);
//Multiply each color by the source alpha, and write in just the color values into the final texture
//TODO: blend states should be constracted once.
BlendState blendColor = new BlendState
{
ColorWriteChannels = ColorWriteChannels.Red | ColorWriteChannels.Green | ColorWriteChannels.Blue,
AlphaDestinationBlend = Blend.Zero,
ColorDestinationBlend = Blend.Zero,
AlphaSourceBlend = Blend.SourceAlpha,
ColorSourceBlend = Blend.SourceAlpha
};
SpriteBatch spriteBatch = new SpriteBatch(CakeEngine.staticDevice);
spriteBatch.Begin(SpriteSortMode.Immediate, blendColor);
spriteBatch.Draw(file, file.Bounds, Color.White);
spriteBatch.End();
//Now copy over the alpha values from the PNG source texture to the final one, without multiplying them
BlendState blendAlpha = new BlendState
{
ColorWriteChannels = ColorWriteChannels.Alpha,
AlphaDestinationBlend = Blend.Zero,
ColorDestinationBlend = Blend.Zero,
AlphaSourceBlend = Blend.One,
ColorSourceBlend = Blend.One
};
spriteBatch.Begin(SpriteSortMode.Immediate, blendAlpha);
spriteBatch.Draw(file, file.Bounds, Color.White);
spriteBatch.End();
//Release the GPU back to drawing to the screen
RenderManager.SetTarget(null);
return(result as Texture2D);
}
