what is self.model.mat:J() ?

[AggrorJorn]

I've been trying to adjust the lua scripts from the metal01 door out of the sdk. The door can rotate around it's axis in the y axis. However I want to rotate my object (copied the script) around the x axis.

When the hinge joint is created it uses some parameter I don't understand.

self.joint = CreateJointHinge(self.body,self.model,pos,self.model.mat:J()

I get the first 3 parameters, but then this last parameter uses ".mat:J()".

First: was does this do? and second: is this effecting the axis direction.

[Canardia]

J is one finger direction of the matrix (up, right, forward). Although many people believe mathematics should use the right hand rule ( http://en.wikipedia.org/wiki/Right-hand_rule ), I think it's better to use the left hand rule ( http://en.wikipedia.org/wiki/Left-hand_rule ), since all good things should grow in positive direction (up=good, right=good, forward=good). Also in 3D graphics, X+ means always right, Y+ means up, Z+ means forward, although many 3D programs do it wrong.

[TylerH]

I, J, and K will give you the local axes of the model relative to itself. The parameter it is passing to the hinge function I believe is the "pin", which is the axis it rotates on.