Manipulating IK objects on the stage with the picker tool

Once you have movie clips defined on the stage and centered properly, you can begin to create your IK chain. This is done by selecting objects in the order that they depend on each other for movement. For example to create an IK chain of an arm that has a 3 bones made up of an 'arm bone' (closest to shoulder), a 'forearm bone', and a 'hand bone' you would first select the movie clips representing the bones in that order... so the 'arm bone' is seen as the anchor and its rotation point remains fixed as the forearm and hand moves.

Creating an IK chain

1. Position your 'bone' movie clips as they would appear in their initial state.
2. Each movie clip that will be in the chain MUST BE ON ITS OWN LAYER.
3. Select the iK'motion Picker Tool on the Tools panel.
4. Select the bones in order from anchor bone to the lowest level bone (ie. arm->forearm->hand)
5. You will see information in the Output panel as each bone is successfully added to the chain.
6. To create a new chain, click the 'NEW SEGMENT' button on the control panel interface.

Adding a 'null' end cap to the chain

The only limitation to the way the chain is set as per steps 1-4 is that there is no way to get rotation in the lowest item in the chain (ie. the 'hand'). In order to overcome this a null bone can be added to the chain. The null is just used to affect the low item in the chain and does not appear in the final animation when the movie is exported. To add a null bone, hold down the SHIFT key and click on the stage the on the position where you would like it to appear. A small circle with crosshairs drawn in the current stroke and fill colors is added to the stage:

The null end cap is the red circle with black cross-hairs. Also notice the messages in the output window explaining what movie clips are part of the chain.

Positioning bones with the Picker Tool

Once you have created your chain, you can use the iK'motion picker tool to drag individual bones while affecting the rest of the chain. Dragging a low-level bone like the 'hand' or 'null', causes all higher-level bones to rotate and drag in response to the movement. Dragging a higher-level bone like the 'arm' moves all children bones along with it.

You may also 'lock' a bone with the Picker Tool by holding down ALT and selecting the bone movie clip. This toggles on/off the locked property. If a bone is locked, it will not move as lower level bones are dragged around. Locking/unlocking can also be achieved in the control panel interface.

One caveat: if you try to position the chain after a motion-path guided tween has been generated with the 'ReAnimate' button you will get the following error message:

You can only position a chain on the last active frame of the timeline or if you remove the motion path for that frame. One way to remove the motion path is to use the 'split animation' button if the current frame is in the middle of a tween. The other way is to manually delete the motion path guide curve in the guide layer. Both of these options require that you hit 'ReAnimate' again for both the current frame and on the next keyframe of the animation.