Normals and disappearing faces in Unity

Sardu · Nov 2013

Hey everyone.

I'm importing a model into Unity that has a hopper at the top. However, with the normals facing outward the inner faces disappear when viewed in the Unity engine. Of course if I reverse the normals, the outside faces disappear.

So how do I approach this? Do I need to extract the faces a bit to provide two faces for the normals to go both ways? Or is there another work around?

Thanks in advance.

Fingus · Nov 2013

Maya has a feature in the Normals menu called Conform which will automatically fix flipped UV's like that.

Sardu · Nov 2013

Fingus wrote: »

Maya has a feature in the Normals menu called Conform which will automatically fix flipped UV's like that.

But if the normals flip won't I just not see the faces from another direction? It seems like I would need to provide another face.

Sardu · Nov 2013

I solved the problem by just remaking the top of the model using a square with extrusions on the inside faces and attaching that to the model.

Bartalon · Nov 2013

I would recommend working with Backface Culling enabled (viewport menu, Shading > Backface Culling) so you can see immediately when an extruded, lofted, or other surface's normals are backwards.

If you find any flipped normals this way, you can use Normals > Reverse to flip them right side out.

electricsauce · Nov 2013

If you want to view a plane from both sides then you need to write a custom shader that has backface culling off. This can be a little more expensive at runtime, so I prefer the method you used most of the time.

Sardu · Nov 2013

electricsauce wrote: »

If you want to view a plane from both sides then you need to write a custom shader that has backface culling off. This can be a little more expensive at runtime, so I prefer the method you used most of the time.

Ah nice. I probably won't use this now but bookmarked for later, just in case.

Normals and disappearing faces in Unity

Replies