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View Full Version : Riging Gag Boxing Glove extendible criss cross

michaelhussar
04-03-2008, 01:56 AM
Sorry for the poor title. I really don't know what this thing is called. However
you can see what I created here so far here: http://www.hitlabstudios.com/testing/criscross1.mov

I'm running Max 9 on Xp pro sp 2


I rigged this to do the animation but I know I that there had to be a better way to do it.

Can someone suggest a good solution for rigging such a gadget? I tried using multiple IK Chains but in the end that didn't quite work out. I had to hand animate a good deal of the
motion to cover up the poor rigging.

thanks Michael
drdubosc
04-05-2008, 03:03 PM
I think you could call it a pantograph. Here's a rig which worked for me:

====
All construction in Z=0. X to the right, Y up in view attached.

Grid spacing in diagram is c system units (substitute your spacing for c in expression below)

Straight splines in red, labeled Ln, Point Helpers green, blue, labeled Pn.

L0: Pivot:(0,0), and aligned to world.
(L0 is root element, controls overall position, rotation)

P0: Parent: L0, (locked to move in Y only, controls extension)
P1: Parent: L0, Wired: Ypos = -P0.Ypos (P0 & P1 are the handles)

P2: Parent: L0, Wired: Xpos = sqrt((2*c*c)-(P0.Ypos * P0.Ypos))
(Pythagoras keeps the length P0-P2 constant)

P5: Parent: P2, Wired: Xpos = 2*P2.Xpos
P8: Parent: P5, Wired: Xpos = P5.Xpos
P11: Parent: P8, Wired: Xpos = P8.Xpos

L1: Pivot: at P0 (local X along its length), Parent: P0, Lookat Constraint: X to P2
L2: Pivot: at P1 (local X along its length), Parent: P1, Lookat Constraint: X to P2

P3: Parent: L2
P4: Parent: L1

L3: Pivot: at P3 (local X along its length), Parent: P3, Lookat Constraint: X to P5

And so on. Remaining points and lines follow same principles.
====

I you want to swing the whole thing around in space, you'll have to set the upnodes on the Lookats carefully. You can put a limit contorller on P0 to stop the whole thing going too far.
michaelhussar
04-09-2008, 01:50 AM
Robin

Thanks so much for the post and the illustration. I'm looking forward to working it out in max now.

Cheers

Michael
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