実験 2.8 collapse 操作の境界問題

May I ask what the structure of virtual facets looks like? Does it cause v3 or v4 to be missing and lead to issues when traversing neighborhoods? Or does each boundary have an independent virtual facet outside? The file provides no explanation, making the code incomplete. Or is this part not being tested?

The bunny_hole file has non‑closed shapes, and it can be tested now.