Welding Meshes

[laurent_delrieu]

@Michael_Pryor continuing here our discussion on meshes

Discretizations of vectorfield in equidistant curves / aligned stripe pattern

It is not my algo, and I am also speaking on mesh welding. Rhinocommon uses an angle tolerance. Mesh edits weld and Petras weld use distance tolerance. That is point I was making The issue with angle is very often (depending how the mesh is made) mesh faces will have microscopic gaps larger than Rhino tolerance, even though it can join because meshes can join even when not touching as you know. The issue is if there is little gaps an angle calc between faces won’t work because it requir…

With same data and same script
Here the result in Rhino 5

Here the result in Rhino 6, so it failed I am obliged to use a special script to do the job

here the script and mesh. 20180819_test_weld.gh (1.3 MB)

@Petras_Vestartas I try to use your component from you plugin Ngon and it tooks 2.3 minutes !!

[Michael_Pryor (ekim)]

Damn it R6, you win again!

[laurent_delrieu]

Yes R6 brings solutions and new problems. @dale, mesh vertices welding works well in Rhino 6 can you tell us what rhinocommon method to use to have the same result?
Thanks

[Petras_Vestartas]

In the component when you add radius these methods are performed:

        mesh.HealNakedEdges(radius);
        mesh.Vertices.CombineIdentical(true, true);
        mesh.Vertices.CullUnused();
        mesh.Weld(3.14159265358979);
        mesh.FaceNormals.ComputeFaceNormals();
        mesh.Normals.ComputeNormals();

        if (mesh.SolidOrientation() == -1)
            mesh.Flip(true, true, true);

        mesh.Compact();

If there is faster method let me know, I can change this.
You can also check method by method which one is slowing down the welding.

Before I used rtree search for welding, but as Michael mention closest distance has its own issues even if it is fast it may result in invalid meshes. Heal naked edges use edge graph to merge adjacent vertices.
This was the topic in this forum (the last comment of @menno I believe it is what heal naked edges is):

Welding mesh vertices by distance

Maybe there is smarter way, but I used as your suggested method: //Store naked mesh vertices and their ids List<Point3f> pts = new List<Point3f>(); bool[] flag = M.GetNakedEdgePointStatus(); allPointsFound = new List<List<int>>(); //History is need to stop searching rtee //When all point groups are found history.Clear(); //Create Rtree RTree tree = new RTree(); for(int i = 0; i < flag.Length; i++){ if(flag[i]){ tree.Insert(M.Vertices[i], i); pts.Add(M.Vertices[i]); } } //Search…

Maybe @dale can give a faster suggestion for welding.

[laurent_delrieu]

Thanks @Petras_Vestartas for the answer HealNakedEdges is the only one I never used and didn’t know. I suspect it is slow. I need to do some test… Your rtree method is fastest on this mesh. I have also to test the exact speed of Rhino weld.