Bug: mesh ruined after moving edge with gumball

[Viterkim (Viktor)]

identical to this thread, but for meshes

Visual bug after extruding/moving edge with Gumball

Hi all. While working on some simple models today I encountered a strange visual bug/glitch when using the Gumball on an edge. This happened on the latest build of Rhino 8. [example 2] [example 3] When moving one edge over an existing one, it left a strange surface behind as seen in the screenshots. It can’t be removed as it is seen as part of the closed polysurface. I hope this can be resolved in an update. Thanks!

works on nurbs, but on a mesh it will be broken and you cannot MeshToNURB (no error but it wont happen). whereas if you do the polysurface first you can flip back and forth between conversions fine.

trying to extrude the sides will just move that side out.

steps:

1. make a MeshBox (1, so not subdivided)
2. grab an edge and slide it down with the gumball (now we have a pretty ramp)
3. try extruding the side face, it will slide out
4. try MeshToNurb, it will not do anything and not complain

[martinsiegrist]

@Viterkim

2. now we have a pretty ramp

Did you move the edge all the way down so it is coincident with another edge?

[Viterkim (Viktor)]

i don’t even get that popup haha. and ye i have grid snap on and it snaps down. you can even grab it as a single edge and the other follows.

but in the nurbs fix, i also bugged out in the same way in 8, but was fixed in 9.

MoveEdge: Prevents creation of bad objects when planar faces are collapsed :...

[martinsiegrist]

I also don’t really need the popup. In some situations it is quite annoying…

Is your mesh a bad mesh?

Run _SelBad or _What

[Viterkim (Viktor)]

yeye it is. but the point is, if you do it in nurbs it doens’t do it(only in rhino 9 has it been added as a fix, which is great).

and other mesh/polygon editing tools it would always be fine when you merge the edges. it’s quite common when dealing with meshes that you want to slide edges together and merge them.

mesh  
  
  ID: faa18abc-57a5-4e4e-adcc-52b54698f785 (4762)
  Object name: (not named)
  Layer name: Default
  Render Material: 
    source = from layer
    index = -1
  
  Geometry:
    Invalid mesh.
    Open double precision polygon mesh: 24 vertices, 6 faces with normals
      Bounding box: (0.000,-5.000,0.000) to (7.000,3.000,6.000)

[martinsiegrist]

@Viterkim

quite common when dealing with meshes that you want to slide edges together and merge them

I see, you’re expecting the result to automatically stitch together the vertices.
I’m using _Stitch for this.

There are two options for merging faces with the gumball

[Viterkim (Viktor)]

But this is different right? i haven’t actually enabled that option, isn’t that for 2 faces joining when you extrude something up into another thing? (so you don’t have to faces inside the model huggin each other having a good time).

Ideally this behaviour that got fixed for nurbs, would also be toggleable and not try to merge/ruin the object, but leave 2 edges alone (if you wanted it). but default behaviour to merge properly (like it does in nurbs in 9) would be very good. (in blender for example you have automatic merge by distance etc, but here just having automatic merge when they align like the nurbs one would be so good).

BUT stitching basically does the correct behaviour, so that is a great workaround in some cases thank you!

actually, for nurbs and version 8 you dont have stitch, so how would you do that without the gumball corrected behaviour?

anyway the buggy behaviour in nurbs that got fixed, would be great to also have it on meshes

edit: and appreciate you helping and using your time!!

[piac (Giulio Piacentino)]

Thanks Viktor

I filed this as RH-97370 for @Joshua_Kennedy to look at.

It the gumball modifies the mesh and makes degenerate faces, those faces should be mended before the new object is added to the document.