That would be tutorial that teaches you “the Carmack's Reverse”. On following tutorial I agree even on siluette construction, I implemented it the same way

http://archive.gamedev.net/archive/columns/hardcore/shadowvolume/page2.html

Hello everyone!

I am very interested in shadow volumes and was wondering how to implement it. I can't really find any good tutorials that walk through some code in webgl (preferably) or opengl. There are a lot of online resources for putting the general steps to words but I don't know exactly how to…