/// <summary>
/// Find the picker's angle of rotation from zero.
/// </summary>
/// <remarks>
/// Once the picker is grasping the pickable object, it will stay on the "surface" of the
/// pickable by maintaining a fixed displacement with a constrain point. The constrain point
/// is a game object that will rotate together with this one. E.g. it can be the edge of the
/// lever. When picker is moved to new position, the position of the new constrain point can
/// be found in turn. Picker's angle of rotation can be calculated from the angle that needs
/// to rotate from zero deg to the direction from centre of rotation to new constrain point.
/// </remarks>
/// <param name="picker">The picker that is grasping the object.</param>
/// <returns>Picker's angle of rotation from zero.</returns>
protected override float GetPickerAngleInRotationAxis(IPicker picker)
{
PickerDexmo pickerDexmo = picker as PickerDexmo;
Transform pickerReference = pickerDexmo == null ? picker.Transform : pickerDexmo.PalmCenter;
// We want the picker transform to maintain a fixed displacement in world space with the
// constrain point, so when picker transform is moved to a new point, the new
// constrain point can be obtained by subtracting the fixed displacement from
// the picker transform.
Vector3 newConstrainPoint = pickerReference.position - PickerFixedDisplacementWrtConstrainPoint;
// Since the object itself is the centre of rotation and will rotate during runtime,
// all the directions here is calculated in parent transform's coordinate.
// transform.position is the centre of rotation. Find the direction pointing from
// centre of rotation to new constrain point position.
Vector3 pickerRelativeDirectionInParentCoordinate =
Miscellaneous.InverseTransformDirectionInParentCoordinate(transform,
newConstrainPoint - transform.position);
// Find the angle of rotation from zero reference to the direction connecting the
// centre of rotation to new constrain point position.
float angle = RotationUtils.AngleInPlane(LocalRotationAxisInParentCoordinate,
ZeroReferenceDirectionInParentCoordinate, pickerRelativeDirectionInParentCoordinate);
return(angle);
}
/// <summary>
/// Get this pickable object's current angle of rotation from zero.
/// </summary>
/// <returns>The current angle of rotation.</returns>
private float GetCurrentAngle()
{
// _zeroReferenceDirection is in local local coordinate, so it will rotate together with
// the pickable object, so _zeroReferenceDirection is more like the minute hand in clock
// that makes an angle with the zero direction determined by _zeroReferenceDirectionInParentCoordinate.
Vector3 currentRotationReferenceInParent = TransformDirectionFromLocalToParent(
_zeroReferenceDirection);
// Get the angle of rotation from zero in the plane normal to the rotation axis
float angle = RotationUtils.AngleInPlane(_localRotationAxisInParentCoordinate,
_zeroReferenceDirectionInParentCoordinate, currentRotationReferenceInParent);
return(angle);
}
/// <summary>
/// Find the target angle of rotation from zero based on current picker's rotation.
/// </summary>
/// <remarks>
/// The picker will maintain a fixed relative rotation with knob since the start of
/// grasping, so given the current rotation of picker, we can compute the new target
/// rotation of knob.
/// </remarks>
/// <param name="picker">The picker that is grasping it.</param>
/// <returns>Target angle of rotation of knob based on the picker's rotation.</returns>
protected override float GetPickerAngleInRotationAxis(IPicker picker)
{
PickerDexmo pickerDexmo = picker as PickerDexmo;
Transform pickerReference = pickerDexmo == null ? picker.Transform : pickerDexmo.PalmCenter;
// Calculate the target rotation of knob based on current rotation of the picker
Quaternion newKnobTargetRotation = pickerReference.rotation *
Quaternion.Inverse(_pickerRelativeRotationWrtKnob);
// Convert the current angle reference from world coordinate to parent transform's
// coordinate. Angle reference is the direction that indicates the current angle
// of rotation from zero.
Vector3 newAngleReferenceDirectionInWorld = newKnobTargetRotation * ZeroReferenceDirection;
Vector3 pickerRelativeDirectionInParentCoordinate =
Miscellaneous.InverseTransformDirectionInParentCoordinate(transform,
newAngleReferenceDirectionInWorld);
// Find the target angle of rotation from zero in the plane normal to rotation axis
float angle = RotationUtils.AngleInPlane(LocalRotationAxisInParentCoordinate,
ZeroReferenceDirectionInParentCoordinate, pickerRelativeDirectionInParentCoordinate);
return(angle);
}
