Box2dLights
This is an example app that creates a 2D Shadow effect. There are a ton of
examples and tutorials online to achieve this. Here are some of the sites I used:
http://www.youtube.com/watch?v=fsbECSpwtig&list=PLFAAD0C6715AF1CE6
http://forums.tigsource.com/index.php?topic=8803.0
https://github.com/mattdesl/lwjgl-basics/wiki/2D-Pixel-Perfect-Shadows
Requirements
OpenFrameworks 008 - http://github.com/openframeworks/openFrameworks
Addons usded ofxBox2d - http://github.com/vanderlin/ofxBox2d