Surfaces turn inside out

I have had a problem from time to time and in most recent versions with surfaces that I am working on reversing the normal side.

When it happens the surface turns black, and the texture shows on the inside. Typically when I join two sets of nodes, but occasionally I will open a file that had been fine and discover that it has come up backwards. These surfaces render fine, and seem to act normally in deformation, but the black just makes them hard to edit.

Has anyone come up with a solution, or workaround?

One thing that I have found is to change the drawtype to solid (Ctrl Z) and position lights to see what I am working on.

Hit cntrl + N and recalculate the normals to the outside?

Hope it’s this simple.

Thanks Enzoblue, I should have been more specific. That works for meshs but not for NURB type surfaces.

I think I have an answer tho.

Here are the steps: (In non-edit mode or object mode)

  1. Copy the surface and use the copy to experiment on [Ctrl.]+[D]

  2. Center the object anchor using Blenders “Centre” button in the edit panal [f9].

  3. Move the object NUMERICALLY to the center of the model space. Use the [N] button and zero ALL of the fields. This will save you a lot for trouble, if you are working from an arbitrary angle or location the object will probably “skew” (the nodes that you will be re-sorting should be lined pretty much lined up with the X axis, you might need to rotate and experiment a little here).

  4. Now [Tab] to edit mode and highlight all of the nodes (Hit [a] key).

  5. Press [s] and without bumping your mouse, press [x] then [Enter]. This will re-sort the nodes along the X axis.

  6. [Tab] out of edit mode and the surface has turned inside out (our outside-in depending on your frame of mind) and the object is repaired…exept that it’s backwards (meaning if it was the “right” fender before now its the “left one”).

  7. Press [s] again and then [x] again and you should have the problem solved. The outside will stay on the outside in the second transformation.

I hope this saves someone the trouble next time.

Select your surface and press W key to switch direction!!
it’s much easier!! :slight_smile:

Lol, it was that simple! Just had the wrong key :stuck_out_tongue:

Easier is better!

Thanks Antonio.

(Select all nodes in edit mode Press [W] Choose switch direction).