Rigid body collission

# 1 05-06-2012 , 11:12 AM

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Hi all,

It's been a while since i've been here but once again I'm running into some problems, so I thought I'd check in again.

I'm using maya 2011 and I'm currently working on a sheathed katana that is being drawn. I made the Katana an active rigid body, and the sheath a passive rigid body but there seems to be no interaction.

Is there something I'm missing?

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# 2 05-06-2012 , 12:13 PM

EduSciVis-er
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What kind of simulation do you have on the sword? It seems to me that that kind of animation would be better suited to just key both.

-stwert

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# 3 05-06-2012 , 12:39 PM

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I'm not sure if it's at all possible in Maya (I've been using quite a lot of other programs to simulate animations) but I want to draw the sword out of the sheath, in a way that they don't collision with eachother, but rather the sword cleanly leaving the sheath. That's why I thought it would be easyest to make the sword itself an active rigid body, and the sheath a passive one, that is held in place with a constraint, so that the sword doesn't go through the sheath.

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# 4 05-06-2012 , 03:36 PM

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If you have keyframe animation on both, the collision won't work, maya will respect the keys. If you want to key the sword coming out and have the sheath respond, then I think (I always get them mixed up) you want the sword as a passive body and the sheath as an active, and don't put keys on the sheath.

-stwert

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# 5 06-06-2012 , 12:43 PM

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I tried to do what you told me, but for some reason, they just don't collide with eachother.

Here's the scene:
https://www.mediafire.com/?wkvsv5yk8kbuk2v

maybe you can tell me what I did wrong?

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# 6 06-06-2012 , 01:31 PM

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I see that you're using the nucleus solver... I think it might be easier if you use the regular dynamics. There's something funny with the scene though, because I can't even get gravity to work on a simple sphere, but I can if I create a new scene.

The other option that I got to work with you file is to make the sheath an nCloth object, and make the sword a passive collider. Then just tweak the nCloth settings to harden the sheath.

-stwert

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# 7 07-06-2012 , 12:17 AM

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Well, I figured if you couldn't get it to work in my scene, then neither could I.
So I picked up another sword, imported it into a clean project, and started again. Now they react really violently to eachother. Unless key the position of the Sheath.

The first 2 frames look good"ish", but then the collision seems to stop working, any idea?

file can be found here:
https://www.mediafire.com/?y03bz4ersov73gc

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Last edited by SilverBlood; 07-06-2012 at 12:26 AM.

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# 8 07-06-2012 , 12:42 AM

EduSciVis-er
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1) Make sure you've got "play every frame" on in the timeline settings
2) Key it to a realistic time, right now it's like 5 frames (?) for the sword coming out, which is blazing fast.
3) It is working, so you just need to constrain the sheath to something, perhaps a hinge constraint to a belt or something?

Dynamics are finicky, play around with the friction and damping and things, and you'll get there. The other thing would be to just keyframe animate it and forget the dynamics. If you're careful, there won't be any interpenetration and you'll get a better result faster. If the point is to learn dynamics, then keep experimenting with things.

-stwert

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# 9 07-06-2012 , 10:49 AM

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Well, I went sorta back to the drawing board, and scaled my sword in a little. Then started doing a little slower animation. Here's the result:
(animation done by maya dynamics)
(rending in mental ray)
Katana Animated in Maya - YouTube

Thanks for all the tips user added image