影子
Dynamic Shadow Projector - Tutorial
http://nyahoon.com/products/dynamic-shadow-projector/tutorial
利用Projector实现动态阴影
http://www.tuicool.com/articles/BRNzEve
ScreenSpaceShadowMask Blur推荐
http://blog.uwa4d.com/archives/ScreenSpaceShadowMaskBlur.html