View Full Version : Cloth exploding on intersection of colision objects

06 June 2011, 09:40 PM
p { margin-bottom: 0.08in; } Cloth explodes on the shoulder and neck area as the character raises his arm above his head. The shoulder geometry goes throw his head, I know its not physically possible to do something like that. But I need to find a solution, I tried painting all the cloth attributes out of the geometry so its only attached to the skin cluster. That solution works for that shot, after the character puts his arm down then the garment does not act like cloth and I can not animate or set keys on the part when I want it to be cloth or skin cluster only.

How would you guys approach this problem? Has any found a solution or a way around it?

06 June 2011, 12:29 AM
Lowering the collideStrength can help with it exploding and selfTrappedCheck on the cloth also helps if the rigid objects force the cloth into self penetration.

06 June 2011, 12:34 AM
use input mesh attract or constraints and either paint and key mesh attract or key the constraint strength or glue...

06 June 2011, 01:01 AM
It is also worth noting that nCloth has special code to deal with trapped clothing when rigid objects interpenetrate( like a hand going through the belly ), however a bug introduced in Maya2011 broke some of this. SelfTrappedCheck no longer worked, but was fixed in 2012. However there was another aspect of the same bug that was missed that also broke some aspects of trapped check. This has not yet been fixed but hopefully a future hotfix will deal with this second problem( although I can't say when such a fix might be available). TrappedCheck is enabled by default on nRigid nodes and it normally helps keep vertices from getting stuck inside the nRigid when forced inside. With this bug, however, vertices can become stuck providing both the cloth and nRigid are using face collisions. If the cloth was using vertex collisions then one can use pushout to force vertices out, while interlocking faces require the trapped check.
One can use things like input attract or constraints to work around this problem for now. As well when items are forced into interpenetration the thickness of collisions can create a strong repulsive force. Lowering the collideStrength basically weakens the repulsion due to thickness without weakening the resistance to pass through each other.( unless you make it zero in which case the collisions are disabled) This can avoid the huge forces resulting from interpenetration that can cause vertices to explode outward.

06 June 2011, 07:44 PM
Thanks guys I will try this out. The animators will take a couple of days to break my rig, so check back some time next week with updates. LOL

07 July 2011, 05:54 PM
Ok I have one more question. I have noticed that cloth has to be set up in the animation file not in the rig file, for some reason referencing makes the cloth not respond. Is that the truth or am I missing something.

In previous projects that was not a problem, now we have a good hand full of shots with charaters with cloth. I would like to not have to create and play with the settings for every shot. I can write something to where creating the cloth and setting the attributes on it, but what about if painting of some sort is needed? Or constraints need to be created and attached. Doing everything shot by shot is something I would like to avoid.

How would you guys recomend I do this?
Can the cloth be set up on the rig file and referenced in the animation file?

07 July 2011, 06:59 PM
should work fine...

but exactly what are we talking about?

are you making one reference file with a complete character and clothing that you are referencing into a scene, changing the animation, and simming?

07 July 2011, 09:29 PM
Exactlly. I want to set up all the cloth objects and the fully rigged character in one file and then reference that in another file animate and run sim.

In the past I have tryed exactlly that. But when I try to run sim afterwards the cloth does not respond to the colision objects or acts like cloth. Maya does not recognize it as a colth object. The colision objects go throw the cloth objects and the cloth intersects with other piaces of cloth.

Given 10 to 30 frames for the cloth to settle, once the animation kicks in same thing happens. Colision objects go throw cloth objects. Sometimes I have lets say a character that has a cotton shirt and a jacket on top. If I create all the cloth objects in the animation file after the animators are done with the animation the cloth will act acordinglly cotton shirt and jacket act like cloth. Same cloth and attributes settings created in the reference file. When referenced in and then run sim the cloth has the same problem colision objects intersecting cloth and cloth intersecting each other.

It some how feels like the cloth calculations is a little retarded. They are slow to calculate. If cloth is created and run sim it calculates fast even when it settles you can see it settle. If cloth is ferenced in, the calculations are slow and it sems like it misses some frames, it does not calculate acuretlly.

07 July 2011, 11:43 PM
Silly question but do you have different FPS playback settings for different scenes... for example is your reference scene 30 but your shot 24?

07 July 2011, 12:12 AM
24. And the playback speed is every frame.

07 July 2011, 07:58 PM
sorry mate, referenced cloth works fine for me...
maybe you should post which maya, and more details, and someone like Duncan will chime in.
or feel free to post a scene and someone will take a look...

07 July 2011, 11:06 PM
Ok will do. I will put something together and posted.

07 July 2011, 06:40 PM
Ok so I have been testing and simming, testing and simming. Everything seems to work fine now, I was using 2010 when I was having the reference issues, now I'm on 2012 and everything seems to work fine. I feel like such a noob. Thanks guys for watching me fumble around. I appreciate all your input. Now I just have to look for the easy button that makes cloth work good. LOL

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