Weld threshold removed from symmetry in 2022?
Hi @gandhics, thanks for your reply!
Note that I was referring to hidden/internal edges within a polygon. I probably should have made that clearer in the image. It was also an exaggerated example to show clearly what's happening. I've added a second, more subtle example that's more likely to occur in an everyday workflow on the right based on the problem that happened to me at the start of the thread.
While there are simple workarounds, like connecting the edges by hand, they aren't always practical depending on the situation, starting objects and desired degree of automation. Basically, the modifier shouldn't touch edges it doesn't cross, hidden or not.
As for the proximity weld (see the geosphere in the example images), the old Symmetry modifier had a true proximity weld around the seam, which potentially might lead to bad geometry in some cases, but mostly does a good automated job of cleaning up the geometry around the symmetry plane (while leaving vertices further away untouched).
In the new one, I can crank the distance as high as I want and only what Max identifies as vertex pairs are welded (or so it seems). Like said, passing the vertex/edge selection of the slice further up the stack might be an alternate solution to that.
Top image is 2022, lower one 2019 (modifiers applied anew) I attached the files, too. My extreme case (upper left) fails in 2019 as well (hadn't checked that before) but the blue shape works in 2019 while 2022 complete changes the internal/hidden edges in that case, too. Haven't looked further into why, might be because the green shape is sliced and the blue is just the half. Ideally, both would not touch any edges the slice doesn't cross.
As for the geosphere, 2019 does a true proximity weld around the seam while 2022 doesn't.
Thanks for the file. A file is always 1000x better than image. 🙂
So, green case is same as before.
Blue case is because it is poly. If you feed mesh, it doesn't happen.
Poly doesn't have a notion of hidden edges, it would likely just re-triangulate after topology changing operations. 3dsMax doesn't guarantee the hidden edge to be remain same when poly/mesh conversion happens.
Green case is interesting. I guess dev would check. But, I personally OK with the new behavior. IF I really want to force old one. I would just use Vertex Weld.
@Noren2 wrote:
As for the sphere, the weld in 2019 is based on the slice and distance threshhold. Other parts of the mesh aren't affected. To imitate that in an automated way with a vertex weld, I'd need the edge or vertex selection from the slice to be passed up the stack (e.g. selecting open edges wouldn't do the trick as there's no guarantee there aren't any other open edges in the mesh). Maybe you can think of something?
Hmm.. so this is a little bit tricky. It looks like 2019 is choosing verts based on distance from slice plane. Actually this was reported as detect(top elements being affected by weld) and one of reason why the weld logic has been changed.
I assume Symmetry is outputting sliced verts selection, I guess it will be helpful.
But, if there was actual gap, the verts wouldn't be selected so it could be not a complete solution.
I think outputting sliced verts selection and pass up to stack is a good idea in anyway.
