Reuse mesh data that is the same

[Ghostkeeper]

3MF contains several ways to re-use meshes in order to reduce the file size. When exporting, we are not using any of these. The problem with implementing this is that we need to somehow figure out that two meshes are the same but under a different transformation. Blender doesn't provide any information on whether the mesh data is the same (but transformed) and has no easy way to compute that either.

To implement that, we'd need to perform a least squares fit to find the transformation matrix that best matches one mesh on another. This would need to be performed for every pair of meshes, which could become very costly in performance.

That's why this feature would also need to include a check mark in the export menu to decide whether to try and optimise the file size or not. The check mark needs to be disabled by default, because people don't normally care about file size much.