To set up a functional Spline IK system, follow these primary steps as detailed by Autodesk Help :
In MotionBuilder Tutorial - 18: Spline IK , you will learn how to use to animate flexible, multi-joint structures like tails, tentacles, and ropes . This specialized constraint aligns a skeleton joint chain along a curve, providing a smoother and more predictable way to achieve complex, aesthetically pleasing shapes than traditional FK or IK rigs. Core Workflow for Spline IK
Under the tab, enter a value for the Number of control nodes . MotionBuilder will automatically create evenly spaced nodes along the skeleton chain. Motionbuilder Tutorial - 18: Spline IK
: Perfect for automating the physics-like movement of hair, whips, or mechanical cables. Motionbuilder Tutorial - 18: Spline IK
: You can adjust the Control node twist axis , Reverse twist , and Twist interpolation settings to manage how the skeleton rotates along its length as the curve bends. To set up a functional Spline IK system,
: Ideal for any appendage that needs to deform in a serpent-like or "gooey" manner, which standard bipedal rigs can't handle.
: For complex characters, these controls can be added to a Character Extension (like a "Tail" extension) to ensure they are properly recognized and baked with the rest of the control rig. Best Use Cases : Ideal for any appendage that needs to
Drag the from the Asset Browser’s Constraints folder into the viewport. Define the Chain :