CGTalk - Trunk Challenge

twohot

03-16-2007, 08:04 AM

I'm rigging an Elephant for a small clip. The rest of the body was relatively easy but the range of motion required for the trunk has drained me of ideas. See attached for the rig (trunk only) and a sketch of the expected roll on the trunk.

Take a look at the Trunk Rig (http://framexframe.ftml.net/cg/trunk_rig)
Take a look at the sketches (http://framexframe.ftml.net/cg/trunk_sketch)
I have set the rig using isolated bones linked by lookat constraints & position constraints for flexibility. I attached point helpers to drive the rig with expression or script controllers. The attempt on expression and script controllers were rather disappointing with bone flying around uncontrollably. I finally settled for reaction controllers - but I feel this is a long route out of the problem

Can someone help me out with scripts, expressions(preferred) that works? -- suggestions very welcome

djlane

03-16-2007, 09:36 AM

Have you considered setting up a splineIK trunk(Not the max default SplineIK which is uncontrollable)?

I think there are a couple of scripts on scriptspot for automating such a setup.

Cheers

Dan

djlane

03-16-2007, 09:53 AM

Here is a quickly knocked up example, i`m not sure if this is the best way to do it but it might give you some ideas.

Cheers

Dan

twohot

03-17-2007, 07:19 PM

Thanks djlane. I have tried that - problem is, animating the trunk with this setup will require a good sense of proportion on the animator's part as the trunk can be easily stretched into an unnatural pose. Again there will be more than one control object holding animation keys...that could mean trouble.

..... reviewing my vector arithmetic.

djlane

03-18-2007, 10:59 PM

That was just a basic setup, you can expand on it. There are ways of limiting the amount the bones are allowed to stretch/reach along the spline. Or if thats a hassle maybe have the main control objects colour change to red if the splines curve length has crossed a certain value.

Hope that helps

Cheers

Dan

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