Shape tweening



    About shape tweens

    In shape tweening, you draw a vector shape at one specific frame in the Timeline, and change that shape or draw another shape at another specific frame. Flash then interpolates the intermediate shapes for the frames in between, creating the animation of one shape morphing into another.

    Shape tweens work best with simple shapes. Avoid shapes with cutouts or negative spaces in them. Experiment with the shapes you want to use to determine the results. You can use shape hints to tell Flash which points on the beginning shape should correspond to specific points on the end shape.

    You can also tween the position and color of shapes within a shape tween.

    To apply shape tweening to groups, instances, or bitmap images, break these elements apart.

    To apply shape tweening to text, break the text apart twice to convert the text to objects.

    The following video tutorials demonstrate how to create shape tweens. Some videos may show the Flash CS3 workspace, but are still applicable to Flash CS4.

    Create a shape tween

    The following steps show how to create a shape tween from frame 1 to frame 30 of the Timeline. However, you can create tweens in any part of the Timeline that you choose.

    1. In frame 1, draw a square with the Rectangle tool.
    2. Select frame 30 of the same layer and add a blank keyframe by choosing Insert > Timeline > Blank Keyframe or pressing F7.
    3. On the Stage, draw a circle with the Oval tool in frame 30.

      You should now have a keyframe in frame 1 with a square and a keyframe in frame 30 with a circle.

    4. In the Timeline, select one of the frames in between the two keyframes in the layer containing the two shapes.
    5. Choose Insert > Shape Tween.

      Flash interpolates the shapes in all the frames between the two keyframes.

    6. To preview the tween, scrub the playhead across the frames in the Timeline, or press the Enter key.
    7. To tween motion in addition to shape, move the shape in frame 30 to a location on the Stage that is different from the location of the shape in frame 1.

      Preview the animation by pressing the Enter key.

    8. To tween the color of the shape, make the shape in frame 1 a different color from the shape in frame 30.
    9. To add easing to the tween, select one of the frames between the two keyframes and enter a value in the Ease field in the Property inspector.

      Enter a negative value to ease the beginning of the tween. Enter a positive value to ease the end of the tween.

    Control shape changes with shape hints

    To control more complex or improbable shape changes, you can use shape hints. Shape hints identify points that should correspond in starting and ending shapes. For example, if you are tweening a drawing of a face as it changes expression, you can use a shape hint to mark each eye. Then, instead of the face becoming an amorphous tangle while the shape change takes place, each eye remains recognizable and changes separately during the shift.

    Shape hints contain letters (a through z) for identifying which points correspond in the starting and ending shapes. You can use up to 26 shape hints.

    Shape hints are yellow in a starting keyframe, green in an ending keyframe, and red when not on a curve.

    For best results when tweening shapes, follow these guidelines:

    • In complex shape tweening, create intermediate shapes and tween them instead of just defining a starting and ending shape.

    • Make sure that shape hints are logical. For example, if you’re using three shape hints for a triangle, they must be in the same order on the original triangle and on the triangle to be tweened. The order cannot be abc in the first keyframe and acb in the second.

    • Shape hints work best if you place them in counterclockwise order beginning at the top-left corner of the shape.

    Use shape hints

    1. Select the first keyframe in a shape-tweened sequence.
    2. Select Modify > Shape > Add Shape Hint. The beginning shape hint appears as a red circle with the letter a somewhere on the shape.
    3. Move the shape hint to a point to mark.
    4. Select the last keyframe in the tweening sequence. The ending shape hint appears somewhere on the shape as a green circle with the letter a.
    5. Move the shape hint to the point in the ending shape that should correspond to the first point you marked.
    6. To view how the shape hints change the shape tweening, play the animation again. To fine-tune the tweening, move the shape hints.
    7. Repeat this process to add additional shape hints. New hints appear with the letters that follow (b, c, and so on).

    View all shape hints

     Select View > Show Shape Hints. The layer and keyframe that contain shape hints must be active for Show Shape Hints to be available.

    Remove a shape hint

     Drag it off the Stage.

    Remove all shape hints

     Select Modify > Shape > Remove All Hints.