Constraining PhysicsSpace into 2 axis

How to constrain a physics space to calculate only x/y or any 2 axis-es. Ignoring another one.

something like this video.


Not possible just like that with jbullet, setAngularFactor is a singular float and not a Vector like in native bullet, people tried this in various ways, basically applying counter-forces, just look in the forum. (and no, its also not available in the native bullet wrapper as its 1:1 with the jbullet version as long as that is the default implementation)

The solution would be creating 2 invisible physics walls with the stones between it.

Hey, I’m curious, how was the moto cross jme game made then?

I think it didn’t have “real” physics… But if it did, jME2 was using ODE, maybe there was some option to do 2d physics, I never got far with it though, it frequently crashed…

I have stumbled upon, jBox2d. I think i should check it out. :slight_smile:

it’s really 2D -.-

well, its those controllers. :stuck_out_tongue: You attach your mesh to those. There is no way to ignore the extra d in jBullet.

@iamcreasy : This was discussed here (you even commented to that post :slight_smile: ):[java]@Override

public void prePhysicsTick(PhysicsSpace space, float f){

Vector3f linearVelocityVector = getLinearVelocity();

Vector3f angularVelocityVector = getAngularVelocity();

linearVelocityVector.z = 0;

angularVelocityVector.x = 0;

angularVelocityVector.y = 0;



}[/java] ended up working for mt4x, sounds like this is exactly what you want.

An integration of jBox2d or another 2d physics library for jme3 would be cool though :slight_smile: It would save quite a lot of computational costs removing one dimension.


yes, I remember that thread :slight_smile:

As said, when we use native bullet by default (or maybe if jbullet adds it, I didn’t sync with jezeks version for long, he’s not very cooperative…) we can constrain both rotation and movement in three dimensions. Any kind of add-on library is welcome though if done the jme3 way :slight_smile:

@normen said:
As said, when we use native bullet by default we can constrain both rotation and movement in three dimensions.

Cool:) Does this mean that it's not at all computed or that it's just constrained?

It doesn’t make such a great difference as it sounds but the axis would “just” be multiplied with the given factor, so its “constrained”.

@makeshift thanks, missed following posts on that thread. I’ll post back if i can make it work.