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View Full Version : Expressions disable joint chain rotation???


rich8606
08-25-2007, 12:47 PM
Hi I have this cockroach character with antennae. I have a problem with his antennae setup.

I have this joint chain which work as a controller for another set of joint chain (with softbody spline IK). I setup each of these joints on this joint chain with both connection editor (direct connection) and expressions, so if I rotate the root joint in X axis and Y axis the antennae curls perfectly and drives the softbody spline atennae (sweet!!). however when I rotate it in the Z axis... 2 of the joints (both of which has expressions) refuse to rotate despite that in the channel window the rotation value registers.

Here's a pic:
http://img262.imageshack.us/img262/204/001oj0.jpg

Here's the expressions I use:

On joint4 rotate X: joint4_l.rotateX=joint3_l.rotateX*1.5
joint4 rotate Y: joint4_l.rotateY=joint3_l.rotateY*1.5
joint4 rotate Z: joint4_l.rotateZ=joint3_l.rotateZ*1.5

the same problem on joint8 (only that the expressions is on joint9)

The problem only occurs on Z axis, X and Y works fine. I check and rechecked my expressions and connection functions, I'm pretty sure I didn't mistype anything. The problem still occurs even after I delete the expressions on joint4_l.rotateZ. strangely It goes away if I delete all three expression functions (joint4_l.rotateX, Y, Z).

JohnPark
08-28-2007, 04:26 PM
Is there any chance the two problem joints are gimbal locked?

rich8606
08-30-2007, 11:18 AM
Errr... What's gimbal locked? Say.. somehow the problem appears and reappears. What gives?

JohnPark
08-31-2007, 06:58 PM
Gimbal is worth searching on these forums for a better explanation, but essentially it is when two rotation axes line up with each other, which effectively removes one axis of rotation.

yenvalmar
09-11-2007, 01:05 AM
the maya hair system dynamic curve itself can easily be used to create a blendable dynamics in a far more elegant manner.

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