View Full Version : nCloth armpits problem - avoid cloth to be affected by fingers\hands

03 March 2011, 07:36 AM
Say I have a girl character which is slapping herself on her hips. I make girl's body passive rigid body, and the skirt - nCloth. And everything's perfect till she touches the skirt as it sticks immideately to the interpenetrating fingers. Of course I could animate her hands so that they don't touch the cloth but there are really hard to avoid interpenetration places like armpits where one can't avoid interpenetration when the caracter holds her hands down. Everytime she raises her hands up - the cloth area around her armpits would follow along in an undesired manner. Help! Thanks in advance!

03 March 2011, 08:19 AM

Though The solution might increase your simulation time but I recommend you try the following options
In nucleus > solver attributes> increase substeps and max collision iterations.
nclothshape > quality settings > Increase max self collide iterations
also use
Trapped Check
Self Trapped Check
Push Out options for better understanding i would recommend you should go through the documentation first.

03 March 2011, 08:43 AM
Increasing substeps is the way to go. Note that you only need to increase it at the time the fingers are about to collide with the skirt until it's stabilized. You can reduce substeps afterwards. So you should set keyframes for substeps.

I do not know how her clothes is modeled. If you model the clothes when the character is at its T-pose, it's likely that you'll encounter the problem you mentioned. Think about if you model the clothes when the character's arms are pointing downwards forming an angle less than 90 degrees with the torso. This would reduce the area of cloth under the armpit and thus would avoid the problem. This is a very superficial tailoring problem. Take a look at the proper character pose when I model the blouse in my blouse tutorial (

03 March 2011, 09:04 AM
Thanks guys! Yep, looks like I should crank up those substeps.. Will try that.

Fantasizer - great simulation and modeling )

04 April 2011, 01:53 AM

I'm having almost exactly the same problem. I've tried increasing the substeps on the solver and the maximum iterations on the cloth, but it doesn't seem to help. Even if I go up to like, 100 substeps and 120 max collision iterations. Do I need to go up even higher? Would changing the time scale help at all?

I'm stuck on two projects with this, I really can't find a good workaround.

04 April 2011, 02:33 AM
If increasing substeps can't solve the problem, increasing it further won't solve it as well. As I said, it's a modeling issue. Try to reduce the surface area. Do not model the clothes in T-pose.

04 April 2011, 07:07 PM
fantasizer is very right with the substeps. if you don't see improvement on like 20 or max 50, don't even bother simulating with more... And yes, I'd agree once more about the modeling. one has to always think about how would things behave in a real-world situation, especially when setting up simulations. (but that's just stating the obvious, lets move on to the actual tip, haha..)

a) one thing to watch out for is the collision thickness. have it on while animating a close proximity 'touching' so you see the distance you can afford. If you throw a passive collider into a cloth and the cloth has nowhere to move away from it, of course it's gonna stay trapped...

b) theres tons of paint attributes maps you can paint on. They act as 'multipliers' of the actual settings on nCloth. If you got bend resistance set on 20, then you can paint 1 where you want those 20, and 0 where you want none. This holds true for most of the stats you can set in the attribute panel. For the armpit issue, i'd recommend playing with stretch and compression attributes. so that it compresses when the arm goes down (so there's less cloth to wrinkle - less margin for error) and so that it stretches when you stretch it up.

c) if your mesh has bad deformations in the shoulder region from the start, or if the cloth is there way too tight, don;t expect magic from the nucleus. First get the deformations right, think about the animation as a whole. Is the character gonna at all put away his cloth? if not, you can deform the mesh in the armpits 'unnaturally' in a sense of making a bigger hole when the arm is down - and that way the cloth would have a place to go when the arm is down.)

d) one thing you could do, but i don't particularly recommend that one, although in some cases it might be exactly what you're looking for, is you could bind the mesh to the skeleton of your character and use the input attract attribute. paint vertex maps for just the areas that you have problems with, and it might be what you're looking for.

bottom line
- keep in mind the collision width
- for the armpits you could paint them to be compressive and stretchy as hell using vertex maps
- input attract mesh
- deformations of the mesh itself

hope this makes sense.

enjoy the easter :)

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