Performance question

Alrighty so first off I'm using MogreNewt but I figure I should post in here since it's not a language-specific question I have.
Basically my game uses uses this physics engine but I'm using it for 2D-style physics. So I've used the Custon2DJoint or whatever to keep all of the bodies on one plane. However this also stops them from rotating along all three axes, which I don't want. What I've done instead is have a plane-aligned "invisible" (i.e. no entity) body attached to another body (and its corresponding SceneNode has the model entity attached) using a UniversalJoint.

Here is my question:
Which is more efficient?
- Do what I'm doing at the moment
- Have two invisible planes directly "in front of" and "behind" the bodies so they don't move much on that axis
- Write my own CustomJoint (looks pretty daunting D: )
- Something else?

writing your own joint?

That looks really intense though :0

Have you ever written your own?

Yes i did. The new interface for joints in Newton 2.xx is much better.

Right now I aa writing joint for car differential.

oh :0

Where'd you learn how to make them?

hmm, good start would be to see code for allready created joints. You have few functions with which you control which axes are locked and other stuff.

I have no idea what I'm doing <___>


What the hell is a linear/angular row?

linear row is that one which does lock movement in some direction.

angular row is lock in rotation.

Check out some of the articles in NGD wiki:

http://www.newtondynamics.com/wiki/inde ... tle=Joints
http://www.newtondynamics.com/wiki/inde ... ing_Joints

In a nutshell, a linear row tries to move together two points of two bodies along given pin direction and angular row attempts to rotate a body to given angle.

uhh... still not sure I get it.

What I basically want to do is prevent any movement along the Y axis. I'm using "null" as my second "body" since it's not attached to anything

Okay I think I got it now

Although it's a bit jittery and sometimes if I push a lot against a wall then I end up moving into another part of the wall a short distance from it >___>

public override void SubmitConstraint(float timeStep, int threadIndex) {
Vector3 globalPos;
Quaternion globalOrient;
// get the global position and orientation
// Not sure if we need the orientation but we need the position at least
this.m_body0.GetPositionOrientation(out globalPos, out globalOrient);
// Set the Y of the new position to 0
// TODO: since we're only constraining it to Y, couldn't this just be 0?
newGlobalPos = globalPos;
newGlobalPos.y = 0f;
// I wonder if there's a way to do this without needing the two rows. Oh well.
// The first argument is the position we'd like to move, the second argument is where we'd like
// to move it to, and the third argument says which vector we want to move it along
addLinearRow(globalPos, newGlobalPos, Vector3.UNIT_Y);
}

Also while I was at it I cleaned up CustomJoint2D a lot. Is there any way I could submit the cleaned up version to mogrenewt?

EDIT: fixed it up a bit