Yes, I beleive people have actually . Here''s one example of a good use for a 3d texture. Say you''re writing a landscape engine (terrain engine). Rather then blending multiple textures over a single quad... (what if you have 3 different types on a single quad, that''s 3 redraws!) you have a 3d texture consisting of all the layers you want (in the order that they will blend) and you can set the correct coordinates in your quad, and blend however many of the layers you need in a single pass. I havent'' really seen many other uses for it, maybe another use would be something like... what if you wanted a completely deformable wall. You could use a 3d texture, so when you remove "chunks" from the wall (which can be done dynamically with splitting the wall triangles) you can modify the depth value of the 3d texture, so you can actually see the "inside" of the walls. (This scenario is best visualized with a brick wall, where when things hit it, they could easily be dislodged and the inside of the wall would be solid). Another use, could possibly be for a simulation of sorts, what about a disection simulation, where the 3d textuer holds the insides of a frog, and you could "slice" it however you wanted to be able to see the inners. There are PLENTY of uses for 3d textures if you put your mind to it. Sure, 99% of the people have no use for them, but it doesn''t mean it''s useless .

Crispy: Performance gain, compared to what??

I haven''t really used 3D textures myself, but I''ve fiddled around with the idea of it.

The only problem with 3D textures is that they consume SOOO much memory!

They aren''t hardware accelerated yet? Are you for real? It would take barely anything extra for the manufacturer to add this into their already vast engine. They are already interpolating the texture x,y coords, they''d just have to interpolate a third z coordinate, and implement tri-linear filtering of a 3d texture isntead of using the bilinear of a 2d texture. If you''ve ever written a 3d engine with texturing, you''d know how simple it''d be to interpolate another variable (like they do for vertex colors, etc). I don''t see why they wouldn''t have implemented this yet, as it''s pretty easy to do using the current type of rendering engine being used .