To invert a polygon (more accurately, to flip the normals of a face or faces) in Blender, you can use the "Flip Normals" function. Here's how:
- Select the face(s) you want to invert. Enter Edit Mode (Tab) and use face select mode (3 or the face select icon in the header). Click on the face or faces you want to invert.
- Access the Flip Normals function. There are a few ways to do this:
- Mesh Menu: Go to Mesh > Normals > Flip.
- Shortcut: Press Alt + N to bring up the Normals menu, then select "Flip".
- Confirm the inversion. The selected faces will now have their normals flipped. This might be visible depending on your shading settings (e.g., enabling "Backface Culling" in the viewport shading options will make flipped faces invisible from the front). You might also see visual differences if you are using normal-dependent effects, such as shading.
Flipping normals is important because Blender uses normals to determine which side of a face is considered the "outside." If the normals are pointing inward, the face might appear invisible or shaded incorrectly. This is especially important for effects like boolean operations, modifiers like solidify, and rendering.
