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tamat
Posts: 21
Registered: ‎07-24-2007

Wrong UVs that get corrected after reexport it

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07-30-2008 02:51 PM
I've got an FBX with only one quad, this quad has two polygons with only one material. This material uses a texture on Ambient and another texture on Diffuse, and everyone of them uses its own UV Channel (despite the texcoords in both channels are pretty the same). I can see it in 3dsMax 2008 and it looks perfect.

The thing is that when I open the FBX using the ImportScene tutorial (2009.1) one of the UV Channels shown is wrong (some texcoords are just 0,0 or other numbers, it looks like they are wrong indexed). My rendered used this example as a base to the importer so my application obviously looks horrible.

You can see an example of the output here, check that the first polygon looks right, but the second has problems:

Mesh Name: entorn
Polygons
Polygon 0
Coordinates: -242.527298, 236.276749, 0.000000
Texture UV UVChannel_1 (layer 0): 0.966771, 0.504206
Texture UV UVChannel_2 (layer 1): 0.966771, 0.746730
Coordinates: -242.527298, 236.276749, 130.069016
Texture UV UVChannel_1 (layer 0): 0.966771, 0.746730
Texture UV UVChannel_2 (layer 1): 0.546403, 0.746730
Coordinates: -242.527283, 0.023589, 130.069016
Texture UV UVChannel_1 (layer 0): 0.546403, 0.746730
Texture UV UVChannel_2 (layer 1): 0.546403, 0.504206
Polygon 1
Coordinates: -242.527283, 0.023589, 130.069016
Texture UV UVChannel_1 (layer 0): 0.546403, 0.746730
Texture UV UVChannel_2 (layer 1): 0.966771, 0.504206
Coordinates: -242.527283, 0.023581, 0.000000
Texture UV UVChannel_1 (layer 0): 0.546403, 0.504206
Texture UV UVChannel_2 (layer 1): 0.000000, 0.000000 <-- !!!!!!!!!!
Coordinates: -242.527298, 236.276749, 0.000000
Texture UV UVChannel_1 (layer 0): 0.966771, 0.504206
Texture UV UVChannel_2 (layer 1): 0.000000, 0.000000 <-- !!!!!!!!!!


Here comes the mistery. If I open the FBX in 3dsmax and change slightly the uvs of the problematic channel then when I reexport it they look fine. But if I don't modify them then they look bad. So I guess the UVs are stored in some kind of Mapping mode that it is not fully supported by the FBX but after modifying them they are transformed to the regular mode.

This is very annoying first because I have lots of FBX and I don't want to go layer by layer modifying the UV Coords for every mesh, the other is because I can't ensure my clients won't have this problem again.

Any idea? I will really appreciate any suggestion.

If you want to try it by yourself... FBX Scene (it has big textures enveded, sorry)
Please use plain text.