UVW mapping question.

[jggibz]

oops

[Iain McFadzen]

There is no problem with unwrapping UVs like that. In fact, if two parts of the texture on any given model are going to be completely identical it would be inefficient not to.

[robinb]

It depends what it's for. If that's going to be for a game, then it's not a good idea because it won't form a good tri-strip. The uv-coordinates have to be continuous for a strip to be formed. You shouldn't use face mapping for the same reason.

In that case it works better to tile the mapping. Map the strip of geometry outside the 0-1 uv range, from 0-4, or 6 or whatever. You will have to crop the map so that all of it's used though.

If it's not for game use, or if stripping isn't a concern, then no, don't bother.

[jggibz]

Originally posted by robinb
It depends what it's for. If that's going to be for a game, then it's not a good idea because it won't form a good tri-strip. The uv-coordinates have to be continuous for a strip to be formed. You shouldn't use face mapping for the same reason.

In that case it works better to tile the mapping. Map the strip of geometry outside the 0-1 uv range, from 0-4, or 6 or whatever. You will have to crop the map so that all of it's used though.

If it's not for game use, or if stripping isn't a concern, then no, don't bother.

It is for a game, but I'm not sure if I need to be concerned about tri-strips b/c I'm uvw mapping a weapon. What is tri-strip/ stripping?
Also, what is the uv range?

[robinb]

If you're mapping a weapon then you'll be using one larger map and tiling won't be relevant. That was more for scenery mapping.

The UV range I meant is when you map something and click the fit button it fits the UVs as closely as possible to the square from 0 to 1. When you unwrap it, you see this square, but you can map outside that and the UV values are just larger than 1 (or smaller than 0). If you set the UVs to high values you'll see the texture wrap around.

Tristrips are more efficient (usually) than simple lists of triangles as you can extend a triangle to make a strip by adding one more vertex. A quad for instance isn't made of two individual triangles (6 vertices altogether) in this case, but the first triangle, then another vertex to build a new triangle (total of four verts).

This can be continued so long as the verts are identical. If they're welded, share normals (smoothing), have the same UV values and use the same material, then they can be made into strips.

There's more info on the game forum-

http://www.cgtalk.com/showthread.php?s=&threadid=112189

[jggibz]

Thanks for your help guys.

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