Inverse Kin CHOP

From TouchDesigner 099 Wiki


The Inverse Kin CHOP calculates an inverse kinematics simulation for Bone objects.

PythonIcon.png inversekinCHOP_Class

Parameters - Kinematics Page

Solver - This parameter defines the method used to determine the motion of the Bone object when it, its ancestor, or its children are moved.

  • None - No motion solution is applied to the Bone object.
  • Show Rest Position - This solver is used to show the rest position of the bones. It orients the bones at the rest position defined by the rest angles in the chain. These rest angles are used in the Inverse Kinematics solver. Therefore, this solver can be used as a helper utility to show you the rest positions of the chain.
  • Show Capture Position - This solver is used to display the rotation values in the capture angles parameter. These parameters are set in the Skeleton sop when a "capture points" operation is performed, or by using the Grab Capture Angles menu. Like the Show Rest Position solver, this solver can be used to return a chain to its capture orientation.
  • Inverse Kinematics - The IK solver tries to position the bones such that the end of the last bone in the chain touches the origin of the object defined as the end affector. The shape of the chain is derived from the rest angles of each the bones in the chain.

In order to adjust the results of the IK solver, you can adjust the rest angles of the bones. Note that the IK solver's solutions are guaranteed to be continuous only for a given set of rest angles. If you animate the rest angles you may end up with chains that jump around. When using kinematics, the rotations given by the kinematic solver can be exported to the bones using by enabling the export flag on the Inverse Kin CHOP. Adding rotation values to bone objects in a kinematic chain is not recommended, as those values will be over-written by the kinematic solver.

  • Follow Curve - This solver positions the bones to be aligned along the first curve in an object. It is useful for animating things such as tails and spines.

Root Bone - The starting bone of the chain; where the chain starts.

End Bone - If you specify a bone as the last bone in chain, then you will be defining a bone chain that has the current bone as the first in the chain and the bone chosen from the menu as the final bone in the chain. This chain includes all bones in between those just chosen.

End Affector - This specifies which object will serve as the chain's end affector.

Twist Affector - If you specify a twist affector, the entire bone chain will twist along the axis from the chain's root to its end-affector so that the first bone is pointing as much as it can at the twist affector. The twist value can be specified as well, and is applied on top of the twist generated for the twist affector.

IK Twist - Amount of twist allowed by the kinematics solution.

IK Dampening - Amount of damping (slows down at the extremes of angular allowability).

Curve Object - Curve object to follow.

Standard Options and Local Variables