3D texture mapping

Question

In the .obj file, you can specify 3 values ​​for the vt line.

vt 0.769645 0.729072 0.00000000

The .obj specification indicates "depth." What does it actually do, and when is it useful?

Answer 1

If you have a 3D texture, it defines the third coordinate. In fact, you can have an image with pixels in 3D instead of 2D and use it for a texture map. This is very common in procedural texture generation because it allows you to create much better “materials” than a 2D image, with much smaller “seams” or “repeating” sections on the texture map.