Dual Behaviour

A Line Behaviour useful for limbs, and perhaps other two jointed items that stay the same length.

There are three flavours of Dual : Normal, Clockwise and Anticlockwise.

Normal one is the only one that can bend both ways.

If used as a foot, Clockwise is good for a stickman walking from left to right. Anti-clockwise for a stickman walking right to left.

Hopefully the following gif animations will make the differences clear :

Dual Behaviour - can bend both ways

Clockwise Dual Behaviour - walk left to right

Anticlockwise Dual Behaviour - walk right to left

You should apply the Line Behaviour to the "foot". The knee's line behaviour doesn't matter because you never need to drag the knee. In fact you can (and probably should) make the knee fixed (static / locked).