Model turns black when I weld verts - how to avoid?

[b.Schulz]

Check the normals.

[Jon Jones]

Okay, what am I looking to be doing exactly?

The problem seems to go away when I do Set Vertex Normals on the whole model, but then when I try to adjust the smoothing groups or anything like that, and then weld verts again, the problem occurs again...

So ... um... what am I missing?

[b.Schulz]

What do you mean weld verts??

What I usually do is when I have the 2 pieces. I go into custom poly display. Say, show normals and hard edges on both objects/meshs. make sure they are all going in the right direction on both objects. Then point snap my verts together. Then I combine the object making it one surface. Then I merge verts on the hard edges. Is that what your doing? "but then when I try to adjust the smoothing groups or anything like that" What does that mean? I have no idea what your talking about right there. :surprised :D

[Jon Jones]

Okay, I guess I should have clarified. It's not two pieces... it's one object, and I'm welding verts together to optimize. I'm not doing anything dumb like welding verts that aren't on either side of an edge or anything. heh

What I do to weld the verts is point snap the two together, select, then I have a keyboard shortcut set to Edit Polygons -> Merge Vertices -> 0.0010 threshold.

Okay, when I say adjusting the smoothing groups, I mean selecting a series of edges and doing Edit Polygons -> Normals -> Soften \ Harden. As far as I knew, that's how smoothing groups were done in Maya... aren't they?

Okay, this is weird. I just repeated what I did before and now, in this one instance, it seems to be working. If I select the entire model's verts, click 'Set Vertex Normal', it'll smooth it out, then I can go through and make whatever changes I want to the smoothing groups and the verts (moving, welding, etc) and it won't 'break' the model like it did before.

I guess I should just start out by selecting all verts and clicking 'Set Vertex Normal' then?

This is weird and confusing. :\

[b.Schulz]

sounds like you got it then?

[Jon Jones]

I think... it kind of looks that way right now but I'm not totally sure. I guess if that works for now I'll do it, but I could well be completely wrong and have to do something differently later as I encounter it. heh

Well, in any case, you did help me find the way to do it. Thanks for your help and your time. :)

[iC4]

hm, I often get the same error

after merging some vertexes the model turns black, and after setting the normals to face all is ok again..........it's annoying :scream:

[Marcel]

I've found that 'set to face' fixes this problem once, but then it'll come back.
If you use 'set to vertex' (perhaps with the 'unlock' option on?) the problem is fixed permanently :)

[Electrofirma]

In the set normals to face options is a check box for "set user normal", make sure that this is shut off. If set user normal is on, it creates an actual normal vertex for each face and that normal doesn't float to follow changes in the face. Also when the number of face/vertices changes the model gets confused and normals jump around to different faces.

When the "set user normal" option is off, the normal is automatically recalculated on the fly to remain oriented to the face. You'll find that once you stop setting user normals, you won't use 'set to face' anymore either, because the normals stay correct.

I usually start a model with a subdivided cube. The first thing I do is harden all edges. As I do extrusions I harden those edges. When the model is getting down to where the shape is fairly well defined, I harden/soften edges to get the surface flow I'm looking for.

Works really great, and I don't even touch set to face or average normals anymore. I can imagine situation where user normals might be needed, but I haven't come across it in average use.

Good luck!

EDIT: I said "I can imagine situation where user normals might be needed, but I haven't come across it in average use.". I want to expand on that by saying... If I did come to a situation where I needed user normals, I absolutely would not set them on the entire model, unless that was the effect I was looking for. User normals should be the exception, not the rule.

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