Cinema 4D Cinema 4D Prime Character Menu Character Tags IK
Function available in CINEMA 4D Prime, Visualize, Broadcast, Studio & BodyPaint 3D
IK

Basic Tag Display Advanced Dynamics

Advanced

Keep Goal

If this option is enabled, the IK goal will move along with the FK when you animate the FK pose for the chain.

Constrain Goal

If this option is enabled, you can no longer move the goal away from the IK chain. The goal then tends to stay at the end of the chain.

Update On Goal

If this option is enabled, the IK solver only updates when you move the goal.

Align Goal

Gives the goal the same rotation as the object at the end of the chain. This can be useful, for example, to keep the hand at the same angle relative to the arm when moving the IK goal.

Update IK on FK

The difference in an IK Chain’s behavior when this option is enabled will differ only nominally to its behavior when this option is disabled - a somewhat different solution will merely be selected. In most cases, slightly better results can be achieved when this option is enabled. Hence, the option is enabled by default.

Use this option to freeze the current FK state, i.e., all changes made to the IK chain (e.g., via keys, interaction, Expressions) will not affect the (internally) saved FK pose.

Usually this option should first be activated once the character pose and IK have been set and you want to make sure no changes will be made.

Max Iterations [0..9999]

Defines the maximum number of calculation loops the IK solver is allowed to go through in order to calculate the IK. In most cases, the default of 9,999 is far greater than is needed, but in any case the solver will stop looping as soon as it has found the best position for the chain, therefore preventing unnecessary slowdown.

For a simple chain, the solver usually only needs about 5 to 20 iterations to calculate the best result. However, there are some situations and options that lead to an increase in the number of iterations required. For example, a stretched chain requires more iterations than a bent chain. The more joints a chain has, the more iterations it requires. Limits can also increase the number of iterations needed, especially if Strength is not set to 100%.

The Max Iterations value is a type of safety net. If the maximum value is reached, the solver stops its calculations and you may find that the chain hasn’t quite reached its goal or the joints aren't in the optimum position.

If you are working with IK chains that you know are very complex and slow to calculate, you can speed up the animation in the viewport by lowering this value. Then, when you're ready to render the animation, you can increase the value again.

Threshold [0..100000m]

This function also stops the IK calculation at a certain point, in this case, when the end of the chain is within a certain distance of the goal. Changing this value usually makes little difference, however, because the solver has its own internal functions to tell it when to stop solving. If the IK chain seems to be taking a very long time to calculate, try increasing this value.