How to properly remove physics joint

[mwissink]

I have recently run into a problem with the physics joints in Babylon. I add a distance joint between two impostors in my scene, but after some time, I would like to remove that joint. Currently on the docs, there is no reference to a removeJoint function, and after looking into some of Babylon's source code, I found the function

link: https://github.com/BabylonJS/Babylon.js/blob/master/src/Physics/babylon.physicsEngine.ts

However,  the function appears as if it is not complete, and I am unsure of the proper way to access it. 

Is there a way to properly remove a physics joint?

[wo997]

Finally I can help someone  

Keep your jointAB in a variable so you can use it later:

scene.getPhysicsEngine().removeJoint(meshA.physicsImpostor,meshB.physicsImpostor,jointAB);

If you want to see my project with helicopter able to crash when forces between body elements are to high just ask me.

[mwissink]

@wo997

Yes! Exactly what I was looking for, thanks.

[blondegeek]

This doesn't seem to be working for me. Has this by chance changed between when this was posted and now?

Here's a playground example: https://www.babylonjs-playground.com/#4J9JBX#1

[Sebavan]

Pinging @RaananW.

[RaananW]

that's an interesing one

A spring joint is actually not a joint, it is an external constraint that calculates the forces it applies on each frame.

This is why removing a spring joint doesn't work. It is specific to this joint and this physics engine. This should, however, be working, as we do abstract the spring aas a joint. To overcome this (temporarily) you can do the following:

https://www.babylonjs-playground.com/#4J9JBX#2

I will add this as an issue.

 

[blondegeek]

Hi @RaananW,

Thanks for the reply and example. Would you like me to add a github issue?

For the use case I am thinking, I will have many spring joints attached to a given sphere and would like to be able to select which joint I would like to remove. I suppose I could do this by just keeping track of what order constraints are added to the queue but would certainly appreciate another option.

Thanks again!

[RaananW]

hi @blondegeek,

A quick follow up - https://github.com/BabylonJS/Babylon.js/pull/5028

 

[RaananW]

Oh, and please create an issue for the second request (removing a specific joint, if more than one is connected to the same impostors). It requires a small architecture change, which I am not sure we will do in 3.3.

Thanks