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Sep 4, 2009 at 6:53 PM


first of all, what exactly does the "Slop" property do?

I can't find any docs on this and I guess my physics domain knowledge is a little bit limited.

Secondly, is there any difference between a AngleJoint and AngleLimitJoint if Upper/Lower limits are equal? (same questions goes for the fixed variants)

Thanks in advance!

Best regards


Sep 4, 2009 at 8:13 PM

Slop in the AngleLimitJoint is a little bit of error. It is used together with the upper and lower limits of the joint. If  the limit+slop is exceeded, the JointError property will have the value of the amount of distance the joint went past the limit+slop.

And to answer your question: No

The AngleJoint has a target angle and the angle limit joint has a upper/lower limit. If you set both the upper and lower limit to be the same, it will act like a AngleJoint. This is also true for the fixed versions.

Sep 4, 2009 at 8:47 PM

Ok, great!

I guess the same goes for Pin/SliderJoints. A Slider with equal min/max distance is the same as a PinJoint?

In that sense, PinJoint and AngleJoint may be seen as redundant? Or do they give some performance advantage?

Best regards


Sep 4, 2009 at 9:31 PM

Yes, pretty much. The pin joint is a slider joint with a fixed distance.

And yes, they might be a little redundant since they provide the same features when the min/max settings are the same. They are mathematical identical and thus you will gain no performance in using the one over the other. You might gain a tiny amount by using a PinJoint instead of SliderJoint in cases where you don't need the min/max settings. The performance would be from the small bound-checks that are not needed in the PinJoint.

Sep 4, 2009 at 9:38 PM

Excellent, then I'm getting it right.

In my integration I want as few joints as possible (less stuff to handle).

Is there any plans on making a Pin/SliderJoint which only has one body and is attached to the world?

Thanks for a great library!

Best regards


Sep 4, 2009 at 9:48 PM

Never had a request for a fixed version of the slider/pin joint. 3.0 will have a different kind of joint and I might take a look at implementing fixed versions there.