http://msdn.microsoft.com/en-us/library/bb203909(v=xnagamestudio.31).aspx
http://xbox.create.msdn.com/en-US/education/catalog/sample/chasecamera
4.1 Third-Person Camera Navigation, Section 4, Game Programming Gems 4
Getting Started with 3D, 3D Graphics with XNA Game Studio 4.0
Third-person Camera Navigation
原文：http://www.cnblogs.com/lilei9110/p/3522406.html