Understanding HingeConstraint in jBullet

Question

I'm using the java port of BulletPhysics engine jBullet. I'd like to make a joints between 2 triangles so that one edge of the first and one edge of the seconds act like a hinge.

But I don't understand how to use the HingeConstraint class because it lacks documentation. What pivotInA and pivotInB are? They are the pivot points of the hinge in respect to the object centre? And axisInA? How does it differs from axisInA?

For two triangles do I have to make 2 Hinge constrains in 2 vertex or 1 in the middle point of the 2 edges of the hinge?

Where can I find a simple working example of this?

Answer 1

When I ported from OpenDE to Bullet, I was puzzled about this as well. I asked on the forum, and the author answered.

In Bullet you can initialize a Hinge constraint that is in a unsatisfied condition.

Only when the axes from both point of views (body A and body B) coincide, the constraint is satisfied.

He makes a good point. Could be useful to serialize a simulation exactly as-is, with constraint error and all.

Answer 2

Hinge constraint between two rigid bodies each with a pivot point that descibes the axis location in local space. Axis defines the orientation of the hinge axis. I have found documentation on this here.