Am guessing that this is not in Cocos2d at the moment.
I want to add shadows to sprites, or particles even. I am guessing the only way to do this - unless there is some OpenGL lighting trick - is to replicate a dark shadow of the sprite on the screen at a lower Z order by creatring a dark sprite masked at a black color, it's position dependent on where the light is; and it's opacity, bluriness etc. set by the user of the shadow API.
The position of the shadow would depend on the position of the light and the z order of the sprite being shadowed, I dont need to deal with shadows on sprites but on the background.
Thats a bit of work and it has performance implications, so before I do it can anyone think of something simpler?