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RIGGING

Limits and IK stops

A limit keeps a bone's turn inside a range, so an elbow or a knee only bends the way it should. An IK stop ends a chain at a bone: dragging a tip below it turns only the bones from there down.

Do it in the editor: guided tour6 steps · about 3 minutes · opens a practice scene

Step by step

  1. Select the forearm's bone

    With the Select tool, click Bone 2, the bone along the forearm. The inspector shows its Bone section.

  2. Turn on Limit rotation

    In the Bone section, tick Limit rotation. A Range row appears with a min and a max, −90° and 90° to start with: how far the bone may turn either way from the angle it was drawn at.

  3. Let the elbow bend one way

    Type 0 in max and press Enter. Bone 2 can now bend the elbow further, up to 90°, but never open it wider than it was drawn.

  4. Reach down with the hand

    Drag the round tip of Bone 3, at the hand, down and to the right. The elbow stays bent and the shoulder turns instead: IK keeps every bone inside its limits.

  5. Make Bone 2 an IK stop

    Click Bone 2 again, then tick Pin: IK stops at this bone. Its joint turns square: a chain dragged from below now starts there.

  6. Drag the hand again

    Drag the tip of Bone 3 up. Only Bone 2 and Bone 3 turn: the upper arm stays where it is.

Good to know. Limits apply while you drag bones, with FK and with IK; a value you type in Rotate isn't limited. An IK stop changes only IK: the pinned bone still turns with the chain below it, and dragging the bones above it works as before.