Sets preferences for inverse kinematics.
The Inverse Kinematics preferences panel contains the following options:
The threshold and iterations settings are a trade-off between accuracy and speed. The two groups of settings let you individually tune the behavior of Interactive IK and Applied IK. Interactive IK provides fast, real-time response, so Interactive IK preferences should be set for speed. Applied IK provides the IK solution to match the follow objects very closely. Applied IK preferences should be set for accuracy.
Position: Sets how close the end effector has to get to the follow object or cursor position to be considered a valid solution. The value represents a distance in the current unit system. Small values increase accuracy but take longer to solve.
Rotation: Sets how accurately the end effector has to match the orientation of the follow object to be considered a valid solution. The value represents a rotation angle in degrees. Small values increase accuracy but take longer to solve.
Iterations: Sets the maximum number of times 3D Studio MAX repeats the IK calculations to find a valid solution. A high iterations value increases the chance that 3D Studio MAX can calculate a valid solution but takes longer to complete.
Use secondary threshold: Compares the second derivative of the end effector to a very small threshold. If it is within the threshold, IK terminates.
Always transform children of the world: This option applies when IK is turned on in both move and rotate mode. It affects only an object that is a direct child of the world and is selected.
For example, if the root of an IK chain is a child of the world, and you are manipulating an object at the end of the chain (the root object is not selected), any constraints set for the root object will be observed. However, if you select the root object and try to move it, its constraints will be ignored.
Single, unlinked objects are hierarchies of one. An unlinked object is its own root and is also a child of the world, so clearing Always Transform Children of the World prevents you from transforming single objects in IK mode.