Backface not showing properly. What am I missing?

Hello everyone!

I have been working with 3D for product vis for a while now, but I’m new to modeling/texturing for real time rendering, so I’m probably missing something.

I have this model of a trophy with ribbons tied to its handles. To decrease polycount, I decided to create the ribbons as double-sided polygons, so then I could untick Backface Culling and get the two sides of the ribbons properly rendered. However, whenever I untick it, I’m getting black polygons on the back side of the ribbons. (See attached image)

I’ve read this topic about someone who was having trouble with Backface Culling and the solution was related to the fact that his GLB had a Root Node. ( GLB - Backface culling ) I have to say that I don’t know exactly what this means, but judging by the picture @Deltakosh shared of the tree and comparing it to mine, I believe I have one as well. Not only one, but several folders (childs?) as you can see in the screenshot.

I’ve used MODO for the model and Substance Painter to create the textures. The GLB is exported directly from Substance Painter.

I’ve searched for hours yesterday before posting, although I believe my problem is simpler than I think.
Can anyone help this clueless soul? XD Thank you very much in advance!

It is extremely difficult to debug a 3D model without the model itself.
Could you share it somehow (Github, Dropbox etc)?

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Hello again @labris and thank you very much for the help.

I’ve followed the doc and I believe I got the model to show in the playground. You need to untick “backface culling” under Trofeu_Mat material to see the issue. Heres the link:

Seems that GLTF format doesn’t understand your trick with double-sided polygons :slight_smile:
The second ribbon doesn’t have any normals at all - see screenshot.

Meanwhile the mesh itself is there

It is not related to Babylon (you can open this file in other viewer and have the same results) but seems that this property doesn’t export properly to GLTF. I had no success with making double-sided cube in C4D.
So while it is in the GLTF specification I would suggest to make the ribbon in a more classical way with usual material so it will work in all cases.

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Hello again Andrei! Thank you very much for your help!

Yes, I agree. Since this is a time sensitive issue (it is a project for a client), I believe that for the time being I’ll choose a more classical route. I think I’ll duplicate the ribbons and flip them, adding a small displacement so it is not overlapping with it’s othe side. Although I’ll add more polys, this way I won’t need to change the texturing style at all, since I already have a couple of items that follow this same style.

After I’m done with the project I’ll get back to this and test a little bit with some ideas I got from your insights. I’ll post the results here.

Once again, I really appreciate all the help! Have a great week!

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