I have a problem to solve:
I do a transform (rotation) on some position of a mesh and after the transformation i can see some holes on the mesh.
There is a way to fill the holes created by the rotation?
With setting up the BackMaterial you will be able to see the inner part of your object - so you will not just simply see through the object, but will see what is inside.
But if you want to fill the holes that appeared after you have moved / rotated some of the positions, you will need to insert additional positions and triangles (TrianglesIndices) to fill the holes. I do not know of any generic solution for that - you will need to calculate or otherwise figure that out based on your meshes and the type of transformation you are doing.
To help you with understanding how your mesh is created (to see the position indexes and indexes of triangles), you can use the MeshInspectorOverlay from Ab3d.PowerToys - see the Utilities / MeshInspectorOverlay sample.