NewtonBallGetJointAngle - how is this done?

[mandy]

Hey all,

I noticed this function (NewtonBallGetJointAngle) in the api, and I would like to do something exactly the same with my custom ball and socket joint. Would anyone care to show how to implement something like this?

[Julio Jerez]

what are you doing?

[mandy]

Hi,

I am trying to figure out the current angles of a joint on each axis.

[Julio Jerez]

The angule of a joint can be determine by projecting the definition axis,
for example on a hinge the angle is calcultether liek this

form teh code

Code: Select all

   // the joint angle can be determine by getting the angle between any two non parallel vectors
   dFloat angle;
   dFloat sinAngle;
   dFloat cosAngle;
   sinAngle = (matrix0.m_up * matrix1.m_up) % matrix0.m_front;
   cosAngle = matrix0.m_up % matrix1.m_up;
   angle = m_curJointAngle.CalculateJointAngle (cosAngle, sinAngle);

su if you wna to control a hinge all you need to do is subclass tha hinge and oveload the submitcontraol function.
the after you call eh base call funtion you can adda noteh angular row to control the joint angle.
you can do the same fo universal,

Ball and socke are more difficult because teh thre euler angle are no indenedent, but you can calculate the angle that aligne teh tow matroces and usin that as one row.
follow but tow perpedicul roiw for stability.
look at the CustomKinematicController.cpp code to see how you can make a joint aligne to a desired oriention, also teh raddoll jpoin des this.