Inverse Kinematic Poses
Inverse kinematics (IK) is a method for animating an object or set of objects in relation to each other using an articulated structure of bones.
Bones allow symbol instances and shape objects to move in complex and naturalistic ways with a minimum of design effort.
For example, inverse kinematics lets you easily create character animation, such as arms, legs, and facial expressions
Adding bones to symbol instance
When you add bones to symbol instances, Flash moves the instances and the associated armature to a new layer in the Timeline panel. This new layer is called a pose layer. Each pose layer can contain only one armature and its associated instance.
To add bones to symbol instances:
- Start Flash and open a new blank document (ActionScript 3.0).
- Begin by creating the symbols that make up the moving parts of your character.
Note: You can import artwork and convert objects to symbols or can draw your artwork. If you create artwork by drawing shapes, convert each shape to a symbol.
- Arrange the symbols in a rough spatial configuration of the object you wish to animate using IK (Figure 1).
In this example, basic shapes were converted to symbols and instances of those symbols were arranged on the Stage to form the character.
- Click an empty part of the Stage to deselect all symbols.
- Select the Bone tool from the Tools panelor press the “M” key to select the Bone tool.
- With the Bone tool, click the symbol instance that is to be the root or head of the armature. Then drag to a separate symbol instance to link it to the root instance.
- As you drag, a bone appears. The mouse pointer changes to a small bone with a plus symbol (Figure 2).
When you release, a solid bone exists between the two symbol instances. Each bone has a head (the wide end) and a tail (the narrow end). Each symbol instance can have only one attachment point. You can edit these attachment points later.
- To add another bone, drag from the tail of the first bone to the next symbol instance you want to add to the armature.
- Link objects with bones in the order of the parent-child relationships you want to create (Figure 3).
- To create a branched armature, click the head of an existing bone where you want the branch to begin. Then drag to create the first bone of the new branch (Figure 4). An armature can have as many branches as necessary, but a branch cannot connect to another branch except as its root.
- Continue to add bones and branches to the armature as needed (Figure 5)
- As you add bones to instances, Flash moves each instance to a new pose layer named Armature in the Timeline panel (Figure 6).
- To reposition the elements of the armature, use the Selection tool to drag either the bones or the symbol instances themselves. Note: To rotate a bone with its child bones without moving the parent bone, Shift-drag the bone.
- After completing your armature, right-click frame 10 in the pose layer and select Insert Pose.
A keyframe appears in frame 10. You can create a new pose of the armature and Flash will interpolate the frames in between, creating the character animation.
- With frame 10 selected, rearrange the pose as you like.
- Likewise add as many poses as required in further frames to complete the animation.
- Select Control > Test Movie > In Flash Professional to preview the movie. The symbols move in relation to each other.
- Close the preview window.