3d textures

I think they are basically like 2d textures, only with a 3rd axis. Like, in a 2d texture, you have x*y pixels. In a 3d texture, you have x*y*z pixels. Like a box full of pixels, instead of a rectangle full of pixels.

I've never seen anyone use them before, and I don't really know what the point of using them is. I'm pretty sure lots of medical imaging apps make heavy use of 3d textures. Not exactly sure how they work it, but I'm pretty sure they do do it. Not many consumer videocards support them though.

One specific instance for using 3d textures would be texture animation... possibly for particles. Just think of your volume texture as a flipbook that you can reference multiple versions of an image with a depth variable. This saves you from having to switch texture contexts when updating your animation.