Flash 8 Cookbook

4.2. Animating Along Curved Paths

Problem

You want to animate along a curved path, instead of in a straight line.

Solution

Use a motion guide. Add further realism by checking the Orient to Path modifier.

Discussion

By default, changes in location are animated in straight lines in motion tweens—going from point A to point B in the most direct route. You may want to animate an element across a curved path. Flash enables you to do so by using a motion guide, which is a path that you can assign to an object as it tweens.

To create a motion-guided tween, you draw a path on a special motion guide layer; this line is visible only in the authoring environment. Then you snap the tweened instance to the path at both the starting and stopping points of the tween, and Flash does the rest. Here are the steps in detail:

1. Create a motion tween, using a graphic, movie clip, or button symbol, as described in Recipe 4.1.

2. With the tweened layer selected in the timeline, add a motion guide layer. You may do so by selecting Insert → Timeline → Motion Guide or by clicking the Add Motion Guide button beneath the layer stack. Alternatively, right-click or Command-click the layer, and select Add Motion Guide. Flash inserts a special motion guide layer above the active layer. The active layer is indented to show that it is guided by the motion guide layer.

3. With the motion guide layer active, use any of the vector tools that allow you to draw a line, such as the Line, Pen, or Pencil tool. Tools that draw fills (such ...