Box2D Forums

Hi everyone,
i would like to get some help creating a gear with a revolute and prismatic joint. I would like to create something similar to the attached image from the Box2D Manual:

I understand that it should be prismatic + revolute but can't figure out how to accomplish it with wck. I am a newbie so...
Any help would be really appreciated so thanks in advance!

Were you able to setup the individual revolute & prismatic joints? If not just look at how they're setup in the demos. Then give both your joints instance names and then for one of them set the "pulleyGearPartnerName" property to the name of the other joint.

Hi, thanks a lot for your quick answer!
I am not sure it is that simple though… On another attempt I had two gears (revolute) working properly. In this case, I am trying to get to work the picture attached yesterday. The revolute joint (#1 over the circle) turns but the prismatic joint (#2 over the rectangle) turns around #1. It doesn't constraint its movement to a vertical axis (as shown in the figure). I haven't found an example like this one in the demo.
I also get this error:

Assertion failed: (def->bodyA != def->bodyB), function b2Joint, file ../Box2D/Dynamics/Joints/b2Joint.cpp, line 173.

[object AlchemyExit]
at <anonymous>()
at <anonymous>()
at Box2DAS.Dynamics.Joints::b2Joint()
at Box2DAS.Dynamics.Joints::b2GearJoint()
at wck::Joint/createGearJoint()
at wck::Joint/createJoint()
at wck::Joint/create()
at misc::Entity/ensureCreated()
at <anonymous>()

Thanks again for any ideas.

Ok lets forget the gear for now and just try to get the prismatic working. If you just drop a prismatic over an object it wont work because it doesn't have any direction. Try putting the joint somewhere outside of the object (or over another object) then setting the "target2Name" to the instance name of your rectangle.

The "joints" demo should have a working prismatic somewhere in there...

Wow!
YES, you put me on the right track. Thanks very much. I got it working.
Great tool and great help!