UV are texture coordinates
that specify how a texture is mapped to a prim's side
. The U is horizontal and V is vertical.
- Q: Why aren't they "HV"? -EepQuirk
- A: The 3D graphics standards use XYZ for positioning, and the three preceding letters, UVW, for the texture coordinates associated with them: U=X, V=Y, W=Z. Yes, there is such a thing as a standard for 3-dimensional textures, and most modern graphics cards support them, but almost nobody uses them compared to 2-dimensional textures which, also by 'accepted practices' means the last axis, Z, is the one dropped from the texture-coordinate specification, meaning that W is also dropped, leaving U and V. That help? - WolfWings
- Z/W is irrelevant since polygons are flat, 2D planes. Using H for horizontal makes more sense. -EepQuirk
- UVW is industry standard, going back maybe as far as 20 years, first appearing in software written by "Wavefront Technologies" who are now known as Autodesk, makers of Maya and connected historical with many other products that shaped the industry. W corresponds to depth not Z; how this differs i cannot say, as i have yet to find any documentation on the topic. Personally i believe it is used for lighting. The only explination as to why it is UVW, like XYZ, they are adjacent; and i have yet to find any documentation giving a reason (and i have been looking). The answer to this question probably has more to do with the temperament of some programer in the 1980's then anything else. -BW
- HPR is industry standard for Heading, Pitch, Roll, the variables used to represent the rotation about an axis. In a left-handed coordinate system, Heading is rotation about the Z axis, Pitch is the rotation about the X axis, and Roll is pitch about the Y axis. -MrShadow