I'm wanting to rig a dog leash for one of my shots but it's not behaving the way I expect.

Can someone who is familiar with dynamic constraints look at this and tell me if this is the way it is supposed to work? And if so, why?

dynamicConstraintMP4.mov

Try it like this...I had to reset it by turning off and on the "Dynamic Options".

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Hmmm, I'm also getting correct results more often from a non-camera view than with the camera.


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Okay, I think this is it...you have to use "Simulate Spring Systems" in the Choreography to get accurate results...at least I think that will cure everything. So, I added a "Target" that is the ground plane and used "Simulate Spring Systems" in the Choreography and it seemed to work fine (I updated the example file). Hope that helps, Robert.

Thanks David. I think I'll report this as a bug because the behavior doesn't conform with what was demonstrated in the tech talk.

I got onto this because I just watched the tech talk.

According to the tech talk, Simulating Spring systems basically bakes the motion into keyframes so the animation can be scrubbed back and forth and/or properly rendered with multipass. But it doesn't make sense that turning the options OFF would actually make some of them work "on the fly".

That smax of 'bug' to me...it's working right, but in the wrong mode. I did not know that SSS(Simulate Spring System...not Sub Surface Scattering) could be used on the dynamic constraint like that...interesting! Once you run a SSS, do you then turn-off the dynamic?

ALSO: David--- you added a 'target'??? I never thought to add a target to a dynamic constraint...is it specifically for collision detection purposes?

you have to simulate first--not a bug. Otherwise you will get unexpected results depending on the number of passes(if using multipass). Simulating first gives a:m channels/keyframes/something to know where the bones should be on each frame.... I always set simulation "off" in the properties and then simulate the dynamics after the animation is complete.

[edit] I just watched your video--that does look like a bug in the refresh. But still: simulate the system before doing final render.

The target would be used for something like a controller on the end of the chain...it shouldn't affect collision detection. It appeared to behave a little better when I made the ground the target...for some reason. It does look like a bug.