BMesh モジュール
公式サイト：
BMesh Module (bmesh) | Blender Python API [Official]
法線を操作する
参考：
bmesh.types.BMVert.normal | Blender Python API [Official]
bmesh.types.BMFace.normal | Blender Python API [Official]
bmesh.types.BMFace.normal_flip | Blender Python API [Official]
bmesh.types.BMLoop.calc_normal | Blender Python API [Official]
update_edit_mesh
ドキュメント：
bmesh.update_edit_mesh | Blender Python API [Official]
参考：
How to get a list of edges of current face in bpy – Blender Stack Exchange
How to edit information in edit mode via object mode – Stack Overflow
normal_update
参考：
bmesh.types.BMVert.normal_update | Blender Python API [Official]
bmesh.types.BMEdge.normal_update | Blender Python API [Official]
bmesh.types.BMFace.normal_update | Blender Python API [Official]
Update Edge Info when using script in Edit Mode – Blender Stack Exchange
calc_area
ドキュメント：
bmesh.types.BMFace.calc_area | Blender Python API [Official]
calc_volume
ドキュメント：
bmesh.types.BMesh.calc_volume | Blender Python API [Official]
コード：
bpy_bmesh_calc_volume – bmesh_py_types.c at dc6fe73e70 – GitHub
参考：
Select objects based on size – Blender Stack Exchange
How can I extract volume and surface information from objects? – Blender Stack Exchange
What’s the algorithm used in bm.calc_volume()? – Blender Stack Exchange