Punch a hole into a texture in OpenGL ES 2.0 (Android)
===

I'm drawing a background texture to the screen, and then a foreground texture, now i wan't to punch a hole into the foreground texture where the user touches the screen. The result should be the foreground texture with a hole, and through the hole you see the background texture. How do i achieve this via OpenGL ES 2.0. I know i can do it with canvas and PorterDuff, but this method is too slow for me.