Perl Graphics Programming

The SWF::Morph Module

A Morph is an object that encapsulates all the different transition states that represent the transformation of one shape into another. To use a Morph, you set an initial state and a final state (both SWF::Shape objects). As the first shape is transformed into the second, all of the original shape’s attributes (color, rotation, etc.) are gradually adjusted to match those of the final state. Once the Morph is placed within a frame, you can set the state of the Morph to any of the infinite number of transitional states between the two extreme shapes using the setRatio( ) method. A value of .5 displays an item that is halfway morphed between the starting and ending state. In the following example, the Morph changes from a square to a star in 10 frames, then changes back to a square in another 10 frames.

Both the initial and final shapes must contain an equal number of points. If the two states are defined by shapes with different numbers of points, you’ll get inconsistent results in the final movie (typically random lines and noise).

In Example 9-4, a red square morphs into a blue eight-pointed star over the course of 10 frames, then morphs back into a square. Figure 9-6 shows a few of the stages.

Figure 9-6. In a morph, the starting and ending shapes must have the same number of points

Example 9-4. Morphing between two shapes

#!/usr/bin/perl -w # # Example 9-4. Morphing ...