Unity is adding edges to imported fbx

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I noticed that Unity is adding edges to my model. Here you can see the model inside Sketchup (where it was made)

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Now here's how Unity is changing my model.

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As you can see Unity is adding an extra edge between some vertices, this is the only place where unity seems to be doing this. Does anyone know why Unity is doing this?

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Answer by Bunny83 · Jul 29, 2015 at 04:06 AM

That makes no sense. Those faces has to be inside the model. Maybe you have somehow disabled them in sketchup but they are still there. At those points shouldn't be vertices and Unity never adds vertices or faces.

My guess is you did not make that model yourself but downloaded it somewhere and you (or someone else) tried to remove those faces which the original author had added. However the faces are not removed but just hidden in sketchup. I never used sketchup, but a quick google showed that it has a "hide faces" feature and here's how you can show them again. You might want to look at some tutorials how to delete a face.

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Rotary-Heart · Jul 29, 2015 at 04:26 AM 0

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You are guessing wrong. It appears to be an issue with that kind of roof shape. Tried the same thing with blender and as soon as I added the face it added that edge by itself.

Here you can see the edges that should contain the face. Similar to the ones to the left.

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Here you can see how blender created the face. As you can see it created an invisible edge (I can't select it and erase it).

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blender-noface.jpg (100.0 kB)

blender-face.jpg (80.0 kB)

Teadaddy · Jul 29, 2015 at 04:37 AM 0

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is that face visible from the opposite side? perhaps you need to flip the normals on it. As far as the original problem, I suggest you take a look at the model and be sure there are onlu 3 and 4 sided faces in it- sometimes it will create a face like that on faces with 5 or more sides.

Rotary-Heart · Jul 29, 2015 at 04:41 AM 0

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No the normals are pointing to the outside. I thought that too, but as you can see in the picture it doesn't do that to the other side (right side of the roof, right side of picture) and its the exact same shape and design, its just flipped.

Bunny83 · Jul 29, 2015 at 04:47 AM 0

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Ok, I'm sorry ;)

However, I have no idea what that blender example has in common with the one in your question... What exact faces in your original mesh do you think that Unity has "created"? You should have highlighted them.

faces

I though you talk about the red marked faces since those aren't visible in the sketchup model. However those seem to be overlapping fragments from the large roof part in the back as i marked green. $$anonymous$$aybe sketchup has some voodoo magic to hide those overlapping faces but failed to export it properly. Did you export the model as fbx? Have you another FBX viewer or could you import the fbx in blender?

I just found out that sketchup seems to have some problems. Did you export as collada? A bit more information would be helpful i think...

edit
Ahh, now i get what you mean in the blender example ^^. Well that happens because you have a polygon there. I'm not an artist, so i can't really give an advice in sketchup of blender. However from a pure program$$anonymous$$g point of view at least in OpenGL (as well as other rendering engines like Halflife forexample) polygones are always convex. So when you make a concave vertex it will still connect the outer corners. For a shape like that you should add an edge from the top of the roof to the concave vertex. I'm not sure if those programs will turn them automatically into triangles or if you have to do something special.

saschandroid · Jul 29, 2015 at 07:08 AM 1

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to triangulate the faces in blender:

 - select the roof
 - go to edit mode
 - select all faces
 - ctrl+t

and the 'edges' will disappear

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Unity is adding edges to imported fbx

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