One of the best things about IK (Inverse Kinematic) in Flash is how easy it is to animate the movement of a bones structure, known as an armature. The Armature Layer can keep track of a series of poses and perform the necessary calculations to move from one pose to another. The Armature Layer has some specific options in the "Properties panel". If you click on an Armature layer, you can access its options in the Properties panel (shown in the image below).
Label - a field which enables you to change the name of the Armature layer.
Ease -> Strength - controls the way the animation speeds up or slows down as it goes along. - A positive value makes the tween to speed up at the end, a negative value slows down.
Ease -> Type - lets you set an "ease type" from a list of options: Simple (Slow), Simple (Medium), Stop and Start (Slow), etc.
Options-> Type - contains two options:
Authoritme - is the default value. When we create multiple poses, Flash animates between them.
Runtime - enables the user to drag your creation around.
Options -> Style - changes the appearance of the bones. It doesn't affect anything except the appearance of the bones.
Springs - enables /disables the possibility of using the "Spring" property, which is located in the Properties panel of each Bone.
Creating Pose Frames and Animation to an Armature
Creating just the right motion is more art than science. There are lots of details in a realistic movement, like the speed at different times, flexibility, naturalness, etc.. Flash has options to add and control these properties by changing the Bones (their position, rotation) in Pose Frames. "Pose Frames" are similar to keyframes, but they are created in the Pose Layer (Armature Layer), and they mark a point in the timeline where you've defined exactly how the animated object is positioned. Flash automatically creates (tweens) the other frames between two Pose frames.
The difference between a Pose Frame and a Keyframe is that a Pose Layer tweens only the position of the symbols or shapes; you can't tween colors, dimensions, or any of the other properties. If you want to change those properties, too, the solution is to create your animation in the Pose Layer, and then convert it in a Movie Clip symbol.
In the next example we create a simple animation to an Armature, we use the Armature created in the previous lesson.
Download and open the Fla file Bone tool with symbol
Click on the Armature_2 Layer. Make sure that in the "Properties panel" the Options -> Type is set to Authortime. Right-click on Frame 25 in the Armature layer, and choose Insert Pose.
At this Pose Frame, change the position of your figure on the Stage (by dragging the shapes). Press "Ctrl+Enter" to test your animation. - The picture below shows the Timeline with the new Pose frame, and the Properties panel of the "Armature layer".
The animation of this example will be something like this:
Like in the Motion Tween, you can apply Ease effect to the Armature Layer, and you can create how many Pose Frames you need to define well your animation. In the Timeline you can Copy, Paste, Clear and Delete Frames from your animation, with the options which appear when you right-click on a Frame.
If you click on a frame of an Armature Animation, the entire layer is selected. To select a single frame, Ctrl+click a frame.
- If you select a frame in an Armature layer and change the position of an object on the Stage, that frame becomes a Pose Frame. - If you want an armature to remain in the same position for a few frames, copy the desired pose (by selecting that Pose frame, then right-click and Copy Pose), and then paste it into another Frame (by selecting that Pose frame, then right-click and Paste Pose). The frames in between two identical pose frames will all be the same. - To delete a frame, select it, then right-click on it and Remove Frame. The Clear Pose option deletes the content on the Stage and keeps the frame in the Timeline.
Properties for Bones
Besides the properties of the Armature Layer, you can edit an IK Bones animation by changing the properties of each Bone. When you select any Bone, the Properties panel displays settings related to that Bone, like in the image below.
The arrows (buttons) in the top of the panel change the selected bone.
Location - Displays the X and Y position, length, and rotation angle. Specify a speed percentage for the bone movement, compared to the other "bones".
Joint: Rotation - Select the Enable check box to allow joint rotation. Select the Constrain check box to constrain the Min and Max angles of rotation.
Joint: X Translation - Select the Enable check box to allow the bone to move along the X axis. Select the Constrain check box to limit the amount of motion along the X axis.
Joint: Y Translation - Select the Enable check box to allow the bone to move along the Y axis. Select the Constrain check box to limit the amount of motion along the Y axis.
Spring - Specify the Strength (stiffness) of the bone spring. Spring makes a child bone resist the movement of a parent bone. - The higher the Strength, the stiffer the spring. - The higher the Damping, the faster the spring diminishes. A 0 value equals full strength.
You can lengthen a Bone by moving the object from the tail of the bone. The object can be moved with the "Free Transform tool". To move a Bone and its childs, without moving its parent, hold down the Shift key and move the bone with the "Selection tool".