Weird uploader behaviour

[BeckHan Ra]

Well, to make it short, I tried to upload a certain model, and when I was getting rid of low LODs, I noticed that model won't degrade further.

Say, usually, by setting lowest LOD to zero, you can make your model look like a bunch of disjoined triangles. But in my case it was actually looking pretty solid, and looking well enough to go even for a "Medium" LOD, with poly count being pretty high.So I ended up having a 5.5+ LI on a model without all three LODs, with a single material, 800 triangles, and a bounding box size of 1.45x1.33x0.52m.

The question is: wtf is this, and is there anything I can do to get it back to the way it used to be?

Thanks in advance!

[Chic Aeon]

I have only had this happen once that I can remember. It was on an mesh that used a few modifiers including solidify which I seldom use, but not sure that was why. The answer is of course to make your own lower LOD model(s). Then it all works as expected.

Some more knowledgable folks will no doubt tell you the "why" of the issue

 

 

[Drongle McMahon]

Have a look at this thread. You may be encountering the same effect. Essentially, the automatic LOD generator has problems with smooth shaded toroidal geometry (things shaped like a distorted torus) when you have no UV map, which can make it fail to reduce the triangle/vertex counts at lower LODs. This can be worked around by UV mapping and/or splitting some vertices (e.g by making a sharp edge). These probably work the same way, as vertices get split (duplicated) in the internal data format by UV seams or sharp edges. So that the vertex duplication seems to get round the problem with the LOD generator, whatever its source.

[BeckHan Ra]

Thanks for the link!

It seems like my kind of issue. With shading set to "flat" it works just as expected. Now I will just enable smooth shading on pieces of my object one by one and see which one gives the biggest trouble.

[BeckHan Ra]

Okay, it looks like uploader doesn't like multiple curved shapes sitting in same place. In my case it was a tissue sticking out from a box, with two same sets of geometry but with normals pointing different direction(to have two-sided material with zero thickness).

After moving one side by 0.00001, I was able to do my stuff properly.

 

[Drongle McMahon]

Interesting. I think you have discovered a whole new class of mesh that confounds the LOD generator (GLOD). I can reproduce this with a simple flat square plane subdivided into 8x8. Even just duplicating two rows (16 quads) without flipping normals, stops  GLOD working from med-lowest. Duplicating the whole thing stops it completely. In this case, UV mapping or flat shading didn't help, but moving the duplicated ones 0.0001 in Z direction (perpendicular to the plane)  let GLOD work poroperly again. It's good to have that documented because duplicating and flipping is going to be used a lot to make 2-sided things.