LOD problems when uploading linked mesh

[Senkiya Zsun]

Hello!

Well I've looked and looked but can't see this problem mentioned.

It's actually a two-phase problem. I uploaded some large meshes separately (4 sides and 4 corners of a temple roof), and they all fit together perfectly in SL ... except for one last join where the faces seem to have got slightly twisted since they just won't align. There's always a very small gap or overlap whatever adjustment I make. I've checked and double and triple checked and nothing is out of alignment in the modelling program (Wings 3D). The faces all mate perfectly except on SL. That's the first part of the problem.

So I tried to upload the whole object with its 8 members in one operation to see if that looked any better. It does. The alignment is perfect. But I can only upload the high LOD. The medium LOD is a complete jumble, as if the uploader couldn't find the right correspondence between the parts. Corners are where sides should be and vice versa, and they have kept their original orientation so they now face any old way, and they are all scaled to the size of the part whose position they have taken. I thought maybe changing the corresponding items in each LOD to have the same name might help, but no.

I tried creating the collada file with 3DSMax instead of wings but it gives the same result. I tried working round it by using the same LOD all the way through but that quadruples the LI and it's just not acceptable. I tried uploading just half the roof (2 corners, 2 sides) at a time. This time the medium LOD is orderly but now the low LOD is jumbled, and anyway the non-mating part of the problem comes back when I assemble the two halves.

So I'm at a loss what to do next. Is this a bug or is there a procedure I haven't found yet for uploading multiple meshes?

Any help will be most gratefully received!

 

[Chosen Few]

Wings is a notoriously buggy program.  Without seeing screenshots, my guess is your vertex winding order got borked somehow, and the COLLADA exporter is confused. What happens if you try exporting to a different format, like OBJ or something, and then re-importing that result, and exporting to COLLADA from there?

Since you've got Max, I do have to ask, why not just work from start to finish in that program?  It's at least a couple orders of magnitude more powerful than Wings, and far more reliable.

[Senkiya Zsun]

Nope, I've tried every export-reimport option I can find, and as I say, I even tried directly exporting from Max. No luck.

If I upload the model intended for the medium LOD as the main model, it's fine; it doesn't get jumbled. If I then use an identical copy of this model as the medium LOD, that's OK too.

So everything is pointing to the uploader not being able to identify which component goes with which, which is understandable as I never actually specify that anywhere except in the component names (I repeat: each component is a separate, uncombined object). Is there some kind of tag I don't know about?

Here's what I mean about jumbling.

I do thank you for trying to help.

PS: Why do I use Wings and not Max? It's what I'm most comfortable with.

 

[Drongle McMahon]

In most cases I have tried, the association of multiple objects between LODs is done on the basis of the order of the <goemetry...>....</geometry> sections in the Collada files, although I am not sure that rule always works. In Blender 2.49, that order is the alphabetical order of the object names. I have no idea what determines the order in other software. A few experiments with some very simple objects might tell you. It could be anything, name, creation order, z axis position, size.....

If the worst comes to the worst, you can try moving these sections around in the Collada file so that they correspond in order correctly. Not guaranteed, but it might work. All the <geometry> sections should be within a single <library_geometries>...</library_geometries> pair.

Whatever object is chosen as the lower LOD version of a high LOD mesh is stretched to fill the same bounding box as the high LOD object. (Strictly, they are all stretched/dqueezed to fit a 1x1x1 cube for streaming and the reverse stretching for the high LOD is applied to all the lower LODs as wee when the object is rezzed). That explains your observation about rotations and sizes.

[Senkiya Zsun]

Drongle, that worked a treat. I reorganized the geometry sections and all levels are now orderly.

All that remains is to find out what criterion Wings uses to organize the file and hope it's something I can control. If not, well I guess rearranging 8 sections isn't too big a pain

Thanks again. The alignment is perfect at last.

[Senkiya Zsun]

I did a quick test and it does seem to be the creation date that determines the export order in Wings. Not the most logical of criteria but it is controllable (just duplicate each component at y-5 or whatever in the order you want them to be exported).