OBJ Import: PreTriangulate or not?

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OBJ Import: PreTriangulate or not? // SDK, Plug-in & 3rd Party Area

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Post by frootee // Mar 6, 2009, 5:34pm

frootee
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I have a question.


When you want to import an OBJ file, are there times when you absolutely must avoid triangulation when exporting to OBJ, for import into truespace?


If so, what are the reasons?


On the other hand, are there times when you absolutely must triangulate the mesh prior to OBJ export?


I'm running into issues with meshes which are not pretriangulated prior to import into Workspace: Missing triangles primarily because I am finding some situations where I have concave NGon faces.


This is for the Workspace OBJ importer I am working on.


thanks!


Froo

Post by jamesmc // Mar 6, 2009, 7:16pm

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Total Posts: 2566
Depends on the modeler for imports.

I think Lightwave exports just about anything, including n-gons in the OBJ format.

3D max I believe only exports triangulated meshes in the OBJ format.

As far as exporting, i would think that triangulation gives the best opportunity for an OBJ to render properly in another application if there are n-gons or holes.

That and the normals being, well normal. :D

Then you get meshes like the one below that have both triangles and quads. :D

Post by RAYMAN // Mar 7, 2009, 12:57am

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Luuv imports and exports just about anything....

and yes ngons IS the preferred way of importing most objects I do...

Why because most of the mesh is imported as quad and only where

it doesnt come together it makes ngons....

thats were you can do a manual transformation to quads.....

But I will throw some ngon meshes with curvature at you maybe these will

help you figure out what aint working.

Post by RichLevy // Mar 7, 2009, 1:12am

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One of the main reasons for the popularity of the obj format was it's use of quads... or more correctly in this case, the lack of converting everything to tris as 3ds and other formats do. Leave it the way I modeled it would be my preference.


Rich

Post by Tiles // Mar 7, 2009, 1:42am

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When you want to import an OBJ file, are there times when you absolutely must avoid triangulation when exporting to OBJ, for import into truespace?

When you need SDS is one case. With tris you can kill the edgeloopflow when you SDS your mesh. Not good for animation needs for example ...

Unwrapper like Roadkill also dislikes tris under some circumstances.

Rich is right, keep it the way it was modeled when possible.

Post by frootee // Mar 7, 2009, 3:21am

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Total Posts: 2667
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ok thanks everyone for your replies. :)
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