PivotJoint constraining two anchors points of bodies to be equal.

The equation for this constraint is:

body2.localPointToWorld(anchor2) = body1.localPointToWorld(anchor1)You may view this constraint as being equal to the DistanceJoint constraint when both its jointMin and jointMax are exactly 0 (In such a case a DistanceJoint becomes degenerate). Compared to the DistanceJoint this is a 2 dimensional constraint.

### Constructor

### Variables

First Body in constraint.

This value may be null, but trying to simulate the constraint whilst
this body is null will result in an error.