I’ve spent the day reading up on shadowing techniques for real-time rendering which can be used in the Ogre3D project I’m working on. I was not familiar with the details of the shadow volume method using stencil maps. It’s actually pretty clever, and it’s interesting to read how John Carmack (ID Software) developed the depth-fail-method (also known as Carmack’s Reverse) to be able to use the stencil shadow technique in scenes where the player/camera was inside the shadow volume. This is how they established the shadows of those things creeping up behind you in Doom 3.
Here’s a comparison I performed in Ogre3D:
Some good resources (some outdated, but the basics still apply):