View Full Version : Constrain Rigid at Multiple Points

03 March 2011, 11:17 PM
I've been searching around the forums and the internet and haven't found a solution to this, although I was expecting it to be relatively straightforward. When you create spring constraints between dynamic objects, it looks like it's only possible to have them connected at the center of mass. So what is the best way to get multiple springs attached at different points to an object, such as a plane suspended from its corners? A common example is simple vehicle suspension, where you'd want the chassis to be spring-constrained to the wheels at 4 points.

I'm not super familiar with dynamics, my failed attempts include creating an extra rigid object for each contact point, but I haven't found a way to connect them so that the parent (chassis) affects and is affected by the spring dynamics. All my experiments with multiple nail constraints have had very unpredictable results.

I guess there may be a soft-body solution, attaching springs to vertices, but I'd prefer to have the output be rigid if possible, so that I don't have to do a geometry constraint for other driven objects.

Any insight?

03 March 2011, 06:27 AM
I think with ncloth you can get what you need.

03 March 2011, 08:53 AM
definitely ncloth, you can 'fake' rigids well and use nconstraints to connect any verts anywhere...

Derek Wolfe
03 March 2011, 06:16 PM
Use a rigid body for each corner of your plane.
Spring constrain them to whatever control you wish.
Pin constrain your plane to each of these corner rigid objects.
snap the pins "initial position" to the respective corner of the plane.

03 March 2011, 10:01 PM
Here is a thread about slightly dynamical car setup.
It uses particles for the shocks...probably not what you are looking for...but its there.

03 March 2011, 01:24 AM
Thanks for the responses. Derek, I wasn't having a lot of luck with pin constraints, but I tried again based on what you suggested and I think that might work. A bit annoying having the extra rigids there, but waddaya gonna do? I'll give nCloth a try as well, although I'd still have to use some sort of geo constraint to control a transform with it, right? Thanks all, cgTalk to the rescue again!

03 March 2011, 09:07 AM
no you can use input mesh attract if you need to have the model follow the original...

Derek Wolfe
03 March 2011, 08:25 PM
ncloth would work, I'm sure. If you want to derive a transform from the ncloth, try a rivet, or follicle, perhaps.

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03 March 2011, 08:25 PM
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