卡通渲染Shader

http://www.opengpu.org/forum.php?mod=viewthread&tid=17071
http://www.opengpu.org/bbs/forum.php?mod=viewthread&tid=17072
http://blog.csdn.net/liumazi/article/details/78858811
https://blog.uwa4d.com/archives/usparkle_cartoonshading.html

https://forum.unity.com/threads/guilty-gear-xrd-shader-test.448557/