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View Full Version : hair driven joint chain tip constraint issue

mindsample
04-04-2009, 10:28 AM
Hi all,

I am using cgTkDynChain.mel from CGToolkit for an auto-creation of a hair driven joint chain.

Whether I do it by hand or use cgTkDynChain.mel I always run into a similar issue with the tip constraint, it seems to be non locked to its locator and swings back and forth a lot. I have been playing with the settings for a while now and can't avoid it, particularly if the forces are strong it bounces quite heavily. Obviously this is quite undesirable as it literally disconnects any wire or cable you might animate from whatever it is you have modelled it with originally.

I dont find any threads on this anywhere and I have not found any way to actually avoid this behaviour.

The base always stays locked to the first joint, the tip appears to be only "spring" constrained to the tip locator?

If you never encountered this try and create a tip constrained joint chain and apply a very strong gravity and you will see what I mean.

Thanks.
mindsample
04-04-2009, 03:18 PM
Upon further investigation I know understand WHY this is actually happening. The joints are a fixed length once they have an IK spline handle (or and IK for that matter) attached to them. For them to mimic the shape of the hair curve they have to slide along the curve to some degree. As a result the tip constraint is not really static.

Any ideas for a work around?
mindsample
04-04-2009, 03:19 PM
One way it works (but very clumsily) is to create another joint, seperate from the others next to the tip and use both the joint chain and the single joint to skin the deformable object. Then if you constrain the standalone joint to the tip (not parent, constrain!) you essentially get the illusion that the tip stays in place as the skinned object will stretch whenever the tip moves away from its original position ...
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04-04-2009, 03:19 PM
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