I’m trying to create some of the extra support arms in the lamp, and trying to get them to rotate as you would expect.
So, I’m starting with the little “Connector” arm between the Lower Arm and the Lower Arm “Support”. See image below for the names:
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I created an extra bone, and unchecked “Connected” to be able to move it halfway along the lower arm bone.
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I added a “Copy Rotation” bone constraint to it so it should copy the “upper arm” bone’s rotation. I figured I would just parent the geometry (the little “connector” that sticks out to the bottom left of the bone), and basically make it stick out in the “negative” direction so it rotates along with the bone.
But I get this really weird flippy behaviour when the Upper Arm bone moves. Not only is the z-rotation of the bone flipping between positive and negative values. The little ‘Connector’ arm is also rotated 90 degrees along it’s local Y-axis causing it to be misaligned. What do?
This is the blend file: https://www.dropbox.com/s/mthrbfhoc791i78/lamp_scene.blend?dl=0
Switch between Rest Position and Pose Position (or scrub the timeline) to see the problem.