Split edge bug in the mesh uploader

[Rick Nightingale]

EDIT: It's not the SL uploader, it's the Collada exporter doing it (despite my efforts to eliminate Blender as the cause). Sorry LL 😢

 

I posted in the mesh forum wondering what I was doing wrong, but I'm pretty sure this is a bug in the mesh uploader. This happens in the latest versions of both Firestorm and LL's viewer.

When I upload a large set (24 objects) of linked mesh in one go, some of the objects with split edges get unsplit (at least, that's exactly what the resultant dodgy shading looks like). Uploading the very same objects one at a time, or even in a smaller group (five or six objects) gives the expected result (smooth shading, stopping at the split edge with no dodgy shading). See...

You might think my split edge is bad on the left, and that I don't know what I'm doing, but there is nothing wrong with the mesh. I've checked and rechecked, looked at the vertex normals, anything I could think of; the mesh is fine (split edges are not exactly complicated).

I've eliminated Blender as the culprit by re-importing its saved .dae file back into Blender. There is no dodgy shading, the mesh from the .dae is like that on the right still.

Exporting the dodgy mesh object out of SL and importing that into Blender shows the split edge is still there and the object looks like it should in Blender, not like it looks in SL.

Final test: export from Blender and upload the previously failed object alone (not in a linkset; it imported looking good, no dodgy shading), exporting that from SL and back into Blender. That looks identical to the above failed object in Blender. The normals are... normal

So, while I cannot see where it is going wrong, something is clearly wrong and it only happens if I upload a larger linkset.

Edit: really final test: I made a .dae of just one object duplicated 24 times (so 24 linked, identical objects), and uploaded that to SL in one linkset. Two thirds of the objects were perfect. One third (of the identical(!) objects) had dodgy shading faults like the above.

Right... I'm getting back to work now I've learned not upload too many objects at once. I think it's LL's way of making us pay more to upload

Edited September 26, 2021 by Rick Daylight

[Rick Nightingale]

Here's a bit more on it... it seems that having two objects with their split edges coincident is causing at least part of the issue rather than it being caused by a large linkset. It doesn't answer why my final test of 24 duplicated objects above failed (they were not coincident, but lined up neatly so I could see them).

Many of the mesh parts have two versions, in exactly the same place and not intended to be used together. Where the split edges are in the same places on the two objects, that's where dodgyness is happening when uploaded:

Here, I've pulled one fin to the side a bit. You can see that the dodgy shading fits together on the two fins. Weird! It's as if the uploader is getting confused by having two different parts in the same place.

Just for clarity, as I mentioned before, if I upload these alone, they have no dodgy shading.

 

 

Edited September 26, 2021 by Rick Daylight

[Coffee Pancake]

This should probably be made into a JIRA and then followed up in person at the content creators usergroup. Do not assume the relevant Linden's will see this thread (even if you ping them)

https://jira.secondlife.com/

 

 

Edited September 26, 2021 by Coffee Pancake

[Rick Nightingale]

If I get time I will. I seem to spend more time chasing and reporting bugs in other people's software than doing my own work at times. Seriously, I once got nicknamed "bugfinder general" in one of my jobs, lol. I seem to attract them.

It's definitely the coincident split edges causing the problem. Everywhere in the linkset that it happens, that's the case. Still doesn't explain why my 24 identical objects test failed so clearly there's more to it. At least now I know what I can upload together, and what not.

Edited September 26, 2021 by Rick Daylight

[Rick Nightingale]

https://jira.secondlife.com/browse/BUG-231269