Stencil buffer question, in Warcraft III

[eden]

As some may have read in a topic a while ago, I had trouble knowing what stencil buffers are. If some have played Warcraft III (kick ass of course), and seen the Human Alliance Arcane Sanctum building, look at the spheres on the roof. They are 2d obviously if you can rotate and get the same image. Now are these the result of stencil buffers? If I read correctly it means applying 2d on 3d?

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[cakecake]

Yes those are stencil buffers. It can be applying 2D on 3D or 3D on 3D. The reason why you would want to use it to apply 3D on 3D is that stencil buffers allow you to easily isolate 3D elements on a screen from each other. For example, if you only wanted a table inside of a 3d room to be alpha blended, you could do this more easily by using stencil buffers.

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