Rigid joints

Troubleshooting physics
1

I’m trying to make rigid joints in jme3(jbullet). But somehow i doesn’t work. Is it possible to make rigid joints? And how do you do them when it’s possible?

2

You would set their limits to zero but they never get completely stiff in bullet, also you might get unexpected results with too low values for some joint types… What you could do is use slider joints, they are the most “stable” by design and set their limits low.

Cheers,

Normen

3

I tried it already with the 6dof and played with the limits but the joint still moves. I have tested it with the sliders joints but the same problem. Any tips for the limits(a lot of limits!)? I have tested it with various settings but it still moves significantly.

4

I wanted to tie up this loose end. The solution that I found that works REALLY well to “link up” rigid bodies that exhibit no forces between them is this…

[java]

joint=new HingeJoint(holderNode.getControl(RigidBodyControl.class), hammerNode.getControl(RigidBodyControl.class), Vector3f.ZERO, new Vector3f(0f,-1,0f), Vector3f.ZERO, Vector3f.ZERO);

getPhysicsSpace().add(joint);[/java]

…The important parameter to notice is the Vector3f.ZERO constants that restrict the axis of the hinges to zero. Thus nullifying any movement between the 2 objects. This doesn’t not lock the physical objects in space, but merely locks them unto each other!

5

I think i achieve this once, doing testing for the ragdoll.

But the rigid joints keep some “elasticity” and bend upon hard collision, i don’t know if it’s the behavior you expect.

It was with a 6dof joint and all the freedom angles were set to 0.