Command: _ShowEdges fails to detect naked edges in meshes

Rhino Rhino for Windows
21

Hi Yianni- as I see it, if you want the exact same result as Join followed by SplitDisjointMeshes, that assumes that edges and vertices match up in order for a Join to occur. IOn the other hand if Join is decided by proximity of the meshes as a whole, then intersecting meshes would be joined, two closed meshes that are very close to one another, or have coincident faces or vertices, would be joined… I’m not sure which is useful.

-Pascal

22

In that case, edges and vertices matching is the safe choice to go with.
Thanks

23

I had an idea while driving home -

  • Make a copy of the meshes
  • Join the copy and split disjoint as per my original script
  • Compare the results to the original meshes. Whatever is identical
    geometry to original is what should NOT be joined. Put the rest of
    the original meshes (to be joined) into an array
  • Delete the copied meshes
  • Join the meshes in the “to be joined” array

Whaddya think? Might it work? I don’t have time to script this right now, maybe later…
–Mitch

24

Large disappointment… The script was easy enough to write. It fails miserably however. Once 2 disjoint mesh parts have been joined and then re-split, Rhino.CompareGeometry (the equivalent of SelDup) no longer considers them identical… despite the fact that they are. Here’s an example:

mesh  
  ID: 6b49ad4f-e36e-40b6-9afc-2f5f438c01ad (17)
  Layer name: Default
  Render Material: 
    source = from layer
    index = -1
  Geometry:
    Valid mesh.
    Open polygon mesh: 9 vertices, 4 polygons with normals
      bounding box: (12.358,-23.1209,0) to (0,-18.3185,)
mesh  
  ID: bc5af1c2-e1f5-4a9d-82d1-e7a5e6717bd3 (95)
  Layer name: Default
  Render Material: 
    source = from layer
    index = -1
  Geometry:
    Valid mesh.
    Open polygon mesh: 9 vertices, 4 polygons
      bounding box: (12.358,-23.1209,0) to (0,-18.3185,)

I suppose there are other, more painful ways to check to see if the meshes are more or less identical, same number of faces, same vertices, but that’s plain painful…

Attached are 2 mesh planes and the copies via copy/join/split disjoint, can you tell me why they aren’t considered "identical?
–Mitch

NoDup.3dm

25

Looks like it re-orders the vertices… :disappointed:
–Mitch