Joint Flexibility

[tonym]

Sometimes Lock Bone doesn't work like you expect it to work and a locked bone will "pop" out of location. Because of this hard-to-predict behavior, some folks get tired of Lock Bone and seldom use it.

To make Lock Bone more user-friendly, add a parameter to Lock Bone called Joint Flexibility.

Joint Flexibility is a measurement of how far a child bone can be pulled away from its parent bone.

This is how it works: After selecting Lock Bone for a bone, you then decide Joint Flexibilty on a scale of 0-5. Zero is the default and means that bone joints do not separate at all (exactly the way it works now). Joint Flexibilty of 1, however, means that a child bone can be pulled a tiny bit away from its parent bone if that separation would keep the locked bone in place. And so forth.

Visualize a foot-shin-thigh-pelvis bone rig, with the foot bone locked. Now imagine using the Translate Bone tool to move the pelvis bone a little, when suddenly--gasp!--the foot "pops" out of location.

Now imagine adjusting the Joint Flexibilty to 1 and the bones forming the knee joint and ankle joint separate a tiny bit and foot bone snaps back into the locked location.

Wow!