Multiply blend mode?

For over 2 years I've been using the additive blend mode daily for almost everything I do. It's ability to brighten colors and use blacks as a mask has proved mighty useful. I now have a need for the complete opposite. In most graphics software there's a blend mode called multiply that darkens colors and leave whites invisible. I need this for a specific case in my game, but the current blend modes aren't giving me much luck.

Any recommendations on how to achieve this effect in C2?

Thanks

There's a WebGL shader that does multiply blend.

This page explains different blending modes, including multiply, in Photoshop and GIMP:

http://emptyeasel.com/2008/10/31/explai ... ay-screen/

I tried those images with the multiply shader in C2 and it looks the same.

I think it's better to think of it more like making the dark colors deeper than removing the white.

That makes it nice for shadows, but it's too expensive as an fx, imo.