Just started getting into C2 and I'm really enjoying how user friendly it is.
I made a quick test of a 2d lighting solution.
<img src="http://dl.dropbox.com/u/5478701/Shadowtest_orig/shadowtest.jpg" border="0">
You can try it out here.
And here's the Capx file.
One problem I'm having with it is the Additive blending mode on the light. It works fine as long as there's a background sprite is on the same layer as the light and shadows, but it won't work if the background sprite is on a layer below it. I can make the Additive blending work by setting "Force Own Texture" to No on the Light and Shadows layer, but this breaks the shadows. So it seems like I can't have both an 'additive' light and 'destination out' shadows at the same time, only one or the other. At the moment in the capx file, there's a second copy of the background sprite in the Light and Shadows layer (as well as one on the Background layer), if you delete this you'll see what I mean by the Addtive mode no longer working .
If there's a way to get that Additive mode working with the shadows, then you should be able to have multiple light sources in different colours, which could be pretty cool.
I hope somebody finds this useful, or could point me in the right direction to get the rest of it working. Thanks!
Edit: I'm getting 60 fps in IE9, but for some reason it only works locally. In firefox I'm getting 50 fps, and in Chome I'm only getting 20! No idea why.