理解四元数的一些文章
http://www.open-open.com/doc/view/46baac6a6b3d4fbfaf6cf0a260add9fc
http://www.3dgep.com/understanding-quaternions/
http://www.cnblogs.com/wqj1212/archive/2010/11/21/1883033.html
http://www.open-open.com/doc/view/46baac6a6b3d4fbfaf6cf0a260add9fc
http://www.3dgep.com/understanding-quaternions/
http://www.cnblogs.com/wqj1212/archive/2010/11/21/1883033.html