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Modding, Mission Design, and Coding => The Modding Workshop => Topic started by: Rga_Noris on May 06, 2010, 01:58:17 am

Title: Edgesplit = non-manifold? (Blender)
Post by: Rga_Noris on May 06, 2010, 01:58:17 am
Sorry to be filling the forums with NoobQ's  :D

Couldnt really find a previous topic that answered this, but I noticed that when making smooth groups in Blender, the edgesplit modifier causes the mesh to become non-manifold (it also creates plenty of extra vertices) along the edges of the smooth groups. According to the wiki, this is a huge no-no, however I have yet to notice any problems with using this modifier.

Any clarification would be awesome.
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: blowfish on May 06, 2010, 02:03:26 am
I haven't noticed any problems with edgesplitting models.  The wiki may be a bit misleading - non-manifold geometry can be used with no problems, but it can be abused too, and weird meshes can be created.
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: headdie on May 06, 2010, 02:14:11 am
What technique are you using to smooth the model? I have been playing with blender for a few months and not hit a split edge issue outside from the supplied polly reduction scripts
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: blowfish on May 06, 2010, 02:25:06 am
Technique?  Depends.  If I'm lazy and the mesh is pretty simple, I will just set the edgesplit to whatever degree measure works best.  For more complex tasks I manually set edges as sharp (though I usually start off by using select->sharp edges).
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: Rga_Noris on May 06, 2010, 02:40:45 am
Technique?  Depends.  If I'm lazy and the mesh is pretty simple, I will just set the edgesplit to whatever degree measure works best.  For more complex tasks I manually set edges as sharp (though I usually start off by using select->sharp edges).

Roughly the same here. I'm a bit of a control freak, so I typically just select the edges by hand and then use the edgesplit mod. As mentioned earlier, in game all is well.
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: Water on May 06, 2010, 05:40:09 am
Couldnt really find a previous topic that answered this, but I noticed that when making smooth groups in Blender, the edgesplit modifier causes the mesh to become non-manifold (it also creates plenty of extra vertices) along the edges of the smooth groups. According to the wiki, this is a huge no-no, however I have yet to notice any problems with using this modifier.
Don't worry about the extra vertices too much. The worst possible thing you can do is have no smoothing -  just Faceted. This page talks about vertex splits -  http://www.ericchadwick.com/examples/provost/byf2.html (http://www.ericchadwick.com/examples/provost/byf2.html)
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: FreeSpaceFreak on May 06, 2010, 06:13:57 am
Indeed, Edgesplit makes the mesh non-manifold - but in the good way. You'll want to check if the mesh is manifold (Ctrl-Shift-Alt-M) before applying the Edgesplit, to make sure that there's no awkward geometry or gaping holes left in the mesh. Then again, especially in detailing, non-manifold add-ons can greatly improve on polycount - but you should only use that when you really know what you're doing.
After applying Edgesplit, each smooth surface is a separate mesh - IIRC, that is the way FS handles smoothing too, so no problem there.
Title: Re: Edgesplit = non-manifold? (Blender)
Post by: Rga_Noris on May 06, 2010, 01:22:22 pm
Thanks everyone for the responses!