How to properly move ProBuilderMesh vertices

Hello !

I try to make a simple stand-alone mesh editor with Unity. As long as ProBuilder exposes a public runtime API I'm currently prototyping a solution built on top of it.

I already have some encouraging results but so far I could not manage to conveniently modify the verticies positions of a ProBuilderMesh.

I looked around a bit in the source code of ProBuilder and actualy the most part is sealed/internal (for good reasons I assume) so that the only way I found to modify vertices is :

Code (CSharp):

1. namespace UnityEngine.ProBuilder
2. {
3.    public static class VertexPositioning
4.    {
5.  
6.        ///The rest of the VertexPositioning class ...
7.  
8.        public static void TranslateVertices(this ProBuilderMesh mesh, IEnumerable<int> indexes, Vector3 offset)
9.            {
10.                if (mesh == null)
11.                    throw new ArgumentNullException("mesh");
12.                mesh.GetCoincidentVertices(indexes, s_CoincidentVertices);
13.                TranslateVerticesInternal(mesh, s_CoincidentVertices, offset);
14.            }
15.  
16.        ///The rest of the VertexPositioning class ...
17.    }
18. }

It fits perfectly for my "move selection" operation but unfortunatly not for the "rotate/scale selection" one.

I tried an ugly workaround to achieve a "rotate selection" operation using VertexPositioning.TranslateVertices(...) individualy on each vertices :

Code (CSharp):

1. public static class ProbuilderMeshExtention
2. {
3.     public static void RotateVertices(this ProBuilderMesh proBuilderMesh, IEnumerable<int> indices, Vector3 pivot, Quaternion offset)
4.     {
5.         List<int> sharedVertices = proBuilderMesh.GetCoincidentVertices(indices);
6.  
7.         foreach (int idx in sharedVertices)
8.         {
9.             Vector3 initPos = proBuilderMesh.positions[idx];
10.             Vector3 rotatedPos = offset * (pivot - initPos) + pivot;
11.             Vector3 translation = rotatedPos - initPos;
12.  
13.             proBuilderMesh.TranslateVertices(new int[] { idx }, translation);
14.  
15.             //proBuilderMesh.SetSharedVertexPosition(idx, rotatedPos);
16.         }
17.     }
18. }

But the result seems ok for some frames and randomely wrong for others (vertices seems swapped) :



Anyway even if it worked I strongly doubt this is a good solution.

Can you show me the appropriate way to modify vertices positions of a ProBuilderMesh please ?

Thanks in advance