   [web] Actionscript 3: Alpha blending using BitmapData.draw
  Recently, I've taken to playing around with ActionScript 3 development using Flex, and I've run across something that puzzles me. Perhaps I'm missing something completely obvious, but...Is there a way to perform (SourceColor*SourceAlpha)+(DestColor*(1-SourceAlpha)) style blending using a BimapData.draw() call without using a Pixel Bender shader? I've perused the possible parameters for BlendMode but none of them seem to offer this sort of blending. I currently use a pixel shader to perform the operation, but I was wondering if there is a more obvious solution, particularly one that doesn't force the requirement of Flash Player 10 as shaders do (not that that is a bad thing, imo).[Edited by - JTippetts on June 22, 2009 11:36:45 PM]
  You could use one ColorTransform each to transform your "source" and "destination" images, then draw them with blend mode set to ADD. I have no idea what the performance of that would be.ie, something like:var src:BitmapData = new BitmapData(100, 100, false, 0xFF000000);var dst:BitmapData = new BitmapData(100, 100, false, 0xFFFFFFFF);var srcXfrm:ColorTransform = new ColorTransform();srcXfrm.alphaMultiplier = 1.0;var dstXfrm:ColorTransform = new ColorTransform();dstXfrm.alphaMultiplier = 0;var rect:Rectangle = new Rectangle(0, 0, 100, 100);while (xfrm.alphaMultiplier > 0) {  srcXfrm.alphaMultiplier -= 0.1;  dstXfrm.alphaMultiplier += 0.1;  dst.draw(..., dstXfrm, BlendMode.NORMAL, ...);  src.draw(..., srcXfrm, BlendMode.ADD, ...);}I didn't test this, so you'd have to give that a shot and let us know if it's tweakable or a waste of time.   