View Full Version : jack in the box rig

04 April 2007, 08:15 PM
I know there's got to be stuff on this ( which I haven't been able to find ) but what's the best way to make a jack in the box rig?

I'm thinking of doing it through IK although it would only have a few joints. Any ideas? I'm assuming the best way would have a lot of joints, like a spine ....

04 April 2007, 03:41 PM
Well, you could create the same effect as a stretchy IK setup.

Like, for example, you create a distance tool, and you can write an expression like this:

if (distanceBetweenShape1.distance <= 10)
//You can replace it with whatever axis your joint scales along
joint1.scaleX = (distanceBetweenShape1.distance / 10)
joint2.scaleX = (distanceBetweenShape1.distance / 10)
joint3.scaleX = (distanceBetweenShape1.distance / 10)

If i'm not mistaken, it should work out. (Don't have access to Maya at the moment. Will test this out when i get a chance.)

To all those uber awesome MEL coders, forgive any errors, i'm horrid at scripting. :/

Or, another method i can think of is, using non linear deformers, like bend and squash. You could add the squash, and use that to squash the geo, along with the bend. (Simple setup, but if you can pull this off correctly, it'll work.)

04 April 2007, 02:51 PM
I made a jack in the box like rig a while ago, I think i did it just with a chain of bones and a IK handle..worked perfectly, Ill try to find the file when i get home,

cheers Koen

04 April 2007, 02:20 AM
dynamically a great touch woulld be to put a spline IK through the skeleton then delete the IK handle, convert the curve to dynamic with the hairsystem, make a NEW spline ik using your new dynamic curve (set the auto create curve option off when you make the IK and make sure to select the new dynamic hair curve instead of the original boring old curve), so you have animated ability to blend between dynamic and hand animation. by animating the base curve of the hair system the dynamic hair will follow it with nice lag, and the amount it follows is keyframable between 100% follow the curve and 100% dynamic motion.. further the BASE curve could be smooth bound to a skeleton with whatever sort of IK rig or other rig, if you arent comfortable directly animating CVs on the curve.. so in the end you could have the head pop up with keyframed animation then bobble around dynamically once it clears the box... cool eh?

it takes longer to type than to really do it :)

04 April 2007, 06:52 PM
you don't even really have to rig it. you could just have the geometry pop out of the box, and use a bend curve to animate the flexible parts. this would create a simple back and fourth action, and you could add more deformation using other deformers. to animate a bend just grab the geometry go to non-linear deformers and select bend. then go into the geometry's inputs and click on the bend. you can key frame the amplitude and direction. would be quick, and easy if that is what you are looking for.

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04 April 2007, 06:52 PM
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