Interface for specifying meaning of generalized coordinates of BallJoint and FreeJoint

[jslee02]

The meaning of generalized coordinates of BallJoint and FreeJoint is not clear.

BallJoint has rotation matrix R as configuration. Possible coordinate charts are:

r1 = log(R)
r2 = inverseEuluerXYZ(R)

FreeJoint has transformation matrix T as configuration. Possible coordinate charts are:

(q1, q2) = log(T)
(q1, q2) = (log(R), p)
(q1, q2) = (inverseEulerXYZ(R), p)

So we need member functions for the coordinate charts of BallJoint and FreeJoint.

enum CoordinateChart
{
  CC_EXP,
  CC_EULER_XYZ,
  // ...
  CC_EULER_ZYX
}

BallJoint::setCoordinateChart(CoordinateChart _chart);
CoordinateChart BallJoint::getCoordinateChart() const;