IK Constraint

Summary

The IK (Inverse Kinematics) Constraint allows you to control a chain of bones using a single point, rather than rotating each bone individually (Forward Kinematics). This is particularly useful for animating limbs like arms or legs, where moving a hand or foot automatically calculates the necessary joint rotations.

Step by Step

1. 01:11
   Creating a Target

   Create an empty group (G) and change its type in the Inspector from "Group" to "Target" to serve as the control point.
2. 01:52
   Applying the Constraint

   Select the last bone in your chain, go to the Inspector, and add an IK Constraint.
3. 02:03
   Linking the Target

   In the constraint settings, use the target selector to pick the Target group you created in step 1.
4. 02:50
   Setting Bone Count

   Adjust the "Bone Count" property to determine how many bones up the chain are influenced by this specific IK target (e.g., set to 2 for a knee/elbow joint).
5. 03:32
   Inverting Direction

   Use the "Invert Direction" toggle if the joints are bending the wrong way (e.g., an elbow bending backwards).
6. 03:52
   Animating IK Properties

   In Animate Mode, you can key both the "Invert Direction" and "Strength" properties to switch between poses or blend IK with Forward Kinematics.

Notes About Current Rive

• FK vs. IK: Forward Kinematics (FK) is default; IK is superior for limbs that need to stay planted or follow a specific endpoint.
• Visual Feedback: Bones under the influence of an IK constraint appear highlighted in yellow in the viewport.
• Hybrid Rigging: You can animate the "Strength" property down to 0% to temporarily disable IK and return to manual bone rotation (FK) for specific frames.