e9092110ff
The duplicated edges were caused by 'oversubdivided' edges, i.e. edges where some of the vertices on them are only connected to two polygons. The fix finds these vertices and 'dissolves' them so that only one edge is created. For most 'normal' meshes this shouldn't occurr, or only very little, so the performance impact of this change should be neglegible. In practice this is also avoidable by triangulating the mesh first. Differential Revision: https://developer.blender.org/D13445