Reverse Normals
From Nevercenter 3D Modeling Wiki
Default Shortcut: None
Menu Path: Modify > Reverse Normals
Description
The Reverse Normals command will reverse the direction of each selected face's normal vector. If you are in object selection mode, all the normal vectors on the selected objects will be reversed. Normal vectors determine which direction a face considers to be pointing "out".
Notes
- You can set an object to display its normals by choosing Show Normals. (See Object Display Mode.)
- Several operations, such as Shell and Boolean, require that an object's normals be aligned in a certain way (usually all pointing out).