Fix object patches

Sometimes an object will retain some surface patches with reversed normals. In this case, you cannot change the surfaces by clicking on them in the Show Normals tool. Instead, you can use the Fix Object Patches tool to isolate the patches and reverse their normals.

The tool also lets you delete unneeded patches; for example if they are duplicated or occluding other objects.

Unify the normals of all patches on a surface

1. Press F7 to show normals.
2. Press F8 to reverse normals for any yellow surfaces. (See Check surface normals.)
3. You may find that when you reverse the normals for a surface, there will always be parts of the surface that stay yellow.
   
4. In this case, select Edit > Fix Object Patches > Reverse Patch Normals.

   The Fix Object Patches window appears.

5. Make sure Reverses Its Normals is selected.

   (This lets you click on yellow patches in the 3D view and reverse their normals.)

   
6. Click on a yellow patch in the 3D view. It changes to blue to indicate its normals are now facing outwards.

   The patch number is highlighted in the Fix Object Patches window, with a check mark under the Reverse column to indicate the change.

   
7. Continue to click on yellow patches to correct all patch normals.

   When you click on another surface with yellow patches, the Fix Object Patches window updates to show the patches for that surface.

Delete patches

In some cases, you may want to delete patches from an object; for example, if they are duplicated or occluding other objects.

1. Press F7 to show normals. (This view is recommended so that you can easily see the patches.)
2. Click on the surface you want to work with.
3. Select Edit > Fix Object Patches > Delete Patches.

   The Fix Object Patches window appears.

4. Select Does nothing.
5. Click over the patch you want to delete. It will appear yellow and its patch number will be highlighted in the Fix Object Patches window.
   
6. Click in the Delete column in the highlighted row.
   
7. The patch disappears, revealing objects beneath it. The Delete column indicates the patch is deleted.
8. You can easily show the patch again by clicking over the Delete column again.
   Note

   You can also select Deletes it in the Fix Object Patches window to delete patches as you click on them, but you will not be able to see the patches until after you delete them.