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PostPosted: 16.09.2010, 12:05 
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Joined: 16.05.2009, 12:43
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I've exported this mesh from max and I'm getting some weird results. Can someone take a look and let me know if they get some nasty vertex positions also?

http://mindflock.com/wp-content/uploads/2010/09/swatguy.zip

I suspect its down to the number of bone weights being applied. But thats only a vague guess.

Ta.


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PostPosted: 16.09.2010, 12:26 
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Looking at the weights, it looks like there are max 3 weights per vertex. Is there a hard limit? Anyone know how to reduce the number of bones influencing any given vertex in max other than using the weight table?


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PostPosted: 16.09.2010, 14:20 
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Joined: 15.02.2009, 02:13
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Location: Sydney Australia
Hi zoombapup,

I can't seem to import that model into maya for some reason, but about skin weights you should be able to have up to 4 influences per-vertex. The hard-limit right now is having a limit of 75 bones influencing the one mesh if you do hardware skinning but that can be solved by splitting the mesh so it's 2 draw calls or just hacking the glsl file to have more (provided your hardware supports a lot of uniforms) or use plain software skinning.

Hope this helps a little bit. What collada exporter are you using, the newer opencollada one or the older fcollada from feeling software?

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PostPosted: 16.09.2010, 14:50 
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Hmm, I cant see any of the verts having more than 4 bone weights. So I guess it cant be that. I guess I should try software skinning and see if that fares any better. There's a switch to enable that somewhere isnt there :)

The collada exporter is the stock one that comes with max 2011, so no idea where its origins are. It seems ok if I dont export the skin, so its likely something thats happening with the skin weights thats messed up. But not sure exactly what yet.


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PostPosted: 16.09.2010, 15:09 
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Hmm, looking at the scene file, it only seems to have 67 or so bones, so I doubt its running into the limits on number of bones. Which definitely suggests the weights are borked somehow.


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PostPosted: 16.09.2010, 15:26 
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Hmm, tried software skinning and if anything it appears worse then hardware!

Wonder whats up here.


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PostPosted: 17.09.2010, 02:32 
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The built-in one for max might be rubbish, I'd say try the opencollada or the one from feeling software. Actually I'm curious to know what exporter they used exactly to export the chicago dude and the knight.... I'm using opencollada for maya and it works ok except animation doesn't export so I think I'll need to try the older one.

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PostPosted: 17.09.2010, 09:15 
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Well, I really need the thing to work. Max 2011 isnt really happy using older plugins. Plus I dont think the open source ones are up to date with max 2011 so I'm screwed if this one doesnt work.


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PostPosted: 17.09.2010, 10:27 
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Ok, I got an opencollada plugin release candidate and exported the mesh:

http://www.youtube.com/watch?v=Ui8CjbOZmjc

The trouble is that the mesh is completely the wrong scale, unfortunately the opencollada plugin doesnt offer the same scale options as the max native one. So I'm stuck again. But its interesting that the file sizes when compared between exporters is massively different. 1 meg for opencollada and 6-7 for max's collada/fbx.


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PostPosted: 17.09.2010, 11:05 
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Joined: 13.11.2007, 11:07
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Could it be that in you video, software and hardware skinning have been applied both? Or is the soldier really that acrobatic? :-)

BTW. concerning the maybe wrong skinning weights,... did you tried to import your original DAE file into another program supporting collada? Would be interesting if that would result in corrupted animations as well (so it's probably an exporter problem) or if it's ok (probably a ColladaConv problem). Note also, that we don't support interpolation in ColladaConv, so animations have to be sampled. Not sure if that was done in your swaguy.dae, just had a quick look at it and stumbled across some BEZIER keywords.


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PostPosted: 17.09.2010, 13:09 
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Hmm, pretty sure I tried both ways. I'll have a look at the samepled options. The animation is meant to be like that (its from a mixamo model, I guess theyre showing off the biped rig, its good for testing the skinning either way).


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PostPosted: 17.09.2010, 17:12 
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Hmmm, weirder and weirder. Ok, so if I export from opencollada I can reimport, if I export from max's collada and then reimport I get what I see in horde. So I guess its a data issue. I'd use opencollada entirely if there were a way to tell what scale the damn model would come out as :) it seems almost entirely weird. Plus the model I'm using has a biped rig on it, which doesnt like scaling at all.

I've managed to get one somewhere near scale now though. So I guess I'll go with opencollada for now. It looks like the main difference is that max's collada file has scale/rotate/translate on the joint nodes and opencollada has a matrix. I'll have to have a look again to see anything else.


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PostPosted: 17.09.2010, 18:32 
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It shouldn't make a difference if the transformation is modeled via a matrix or separate values. Both should be handled fine by the converter. But if reimporting fails even on max itself, I guess there's really something wrong in the exporter. I don't have much experience with modelling tools, but when we coded the exporter for blender I think we had a lot of trouble with the joint matrices. Depending on how the skeleton was assembled the export sometimes worked and sometimes not. I can't remember what was the reason but it might be the case, that the max exporter works just fine with another model but not with this special one. But as aleady mentioned I don't have much experience with asset creation


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PostPosted: 18.09.2010, 04:37 
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I'm hacking the collada converter right now to add options to optionally store or not store normals/tangents/bitangents and to see if I can add vertex colours with morph target ability (for this weirdo skybox I'm making, I want animated coloured transitions which work on ES 1.1, long story) and I saw that the converter does scale internally by like 0.1x so plugging that to a parameter flag might help here.

Depending on the rig it is always difficult to scale one in the 3D application, you need to work out the right stuff to scale all at the same time and then resetting transforms/rotate/scale can wreck havoc very well, it's a nightmare... :)

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