Meshes Point-editing: How to delete from my mesh a loop of vertices points without losing vertex normal?

Rhino Rhino for Windows
1

My simple cone mesh has too many triangles.
I wish to select a loop of mesh points and delete them without destroying the mesh or losing the vertex normal.

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image836Ă—1195 347 KB

How to delete vertices loop?
Is that possible or is a missing feature?

2

You can’t delete vertices without opening a hole in the mesh. A single MeshFace (triangle or quad) is made out of only corner vertices (or “corner points”) with no vertices between these corners.

So, a vertex is a 3D point in space and a compound mesh consists of a long list of such points. These points are the “concrete” parts of a mesh. Therefore, deleting a single MeshFace doesn’t automatically delete any of its vertices (corners), since any individual vertices can be a “corner” also for adjacent MeshFaces. And so on.

But when you delete a vertex you can be sure that one or more MeshFaces disappear. A hole will be the result, in the best case.

So a MeshFace doesn’t define any spatial data like the vertices do, it only holds a list of indexes (references) to that long list of “corner points”. This is why you have a broken MeshFace and a broken mesh if one of the corners go missing.

So, in order to “delete a row of vertices” you have to look up every MeshFace referencing those vertices, and replace the index referencing any of the deleted vertices with the nearest remaining vertex which the surface should "stretch itself over to.

// Rolf

3 Likes
3

Ok, Thanks for the extended answer.
I was expecting a function like _Merge2MeshFaces but having as an input row of vertices or mesh edges.
So I can try using Grasshopper to create a function like this, correct? or there is a better approach?