http://gad.qq.com/article/detail/28328
https://blog.csdn.net/langresser_king/article/details/48914901
https://blog.csdn.net/gongyiling3468/article/details/47803619
https://blog.csdn.net/qq18052887/article/details/80387987
http://www.atool.org/poly_curve.php
https://blog.csdn.net/puppet_master/article/details/79859678
https://blog.csdn.net/lynon/article/details/79018695
https://www.bilibili.com/video/av29599657?share_medium=android&share_source=qq&bbid=BC9E5A29-D393-414E-91FA-1C885826E6DC28946infoc&ts=1534689153066
https://github.com/MaxwellGengYF
https://www.assetstore.unity3d.com/cn/?stay#!/content/119877
https://zhuanlan.zhihu.com/p/34894883?edition=yidianzixun&utm_source=yidianzixun&yidian_docid=0Id1ACoW
http://jcgt.org/published/0003/02/03/paper.pdf
https://www.zhihu.com/people/ycz-19/posts
https://cloud.tencent.com/developer/article/1005933
http://gad.qq.com/article/detail/45224
https://github.com/StarsX/RayTracedGGX
http://gad.qq.com/program/translateview/7166529
https://seblagarde.wordpress.com/2013/01/03/water-drop-2b-dynamic-rain-and-its-effects/
http://www.reedbeta.com/blog/hows-the-ndf-really-defined/
https://zhuanlan.zhihu.com/p/53086060
原文：https://www.cnblogs.com/niomaa/p/10318824.html