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View Full Version : Noob Question: UVW map. Whats the W really?



probiner
10-19-2009, 12:20 PM
ok so what does W coordinate stands for?

Cohen
10-19-2009, 12:30 PM
UV is just a standard cartesian system, representing x,y values. Since the UV data is associated with 3d data, which I believe is an "ordinal system" (don't quote me on that though), the data must wrap to 3 places. Hence the W, as in (u,v,w) => (x,y,z). Otherwise, a point (u,v) can not be wrapped to its "ordinal."

Ernest
10-19-2009, 01:49 PM
You might question why you need a depth coordinate like W for a 2D plane. One reason is because it's sometimes useful to be able to flip the orientation of a map, relative to its geometry. To do this, you need the third coordinate. The W coordinate also has a meaning for 3-dimensional procedural materials.

Source is planet Unreal: http://fordy.planetunreal.gamespy.com/gradientssmeshtutorials/uvw.html