ActionScript: The Definitive Guide

Some Applied Examples

We’ve had an awful lot of variable theory. How about showing some of these concepts in use? The following examples provide three variable-centric code samples. Refer to the comments for an explanation of the code.

Example 2.6 chooses a random destination for the playhead of a movie.

Example 2-6. Send the Playhead to a Random Frame on the Current Timeline

var randomFrame;            // Stores the randomly picked frame number
var numFrames;              // Stores the total number of frames on the timeline
numFrames = _totalframes;   // Assign _totalframes property to numFrames

// Pick a random frame
randomFrame = Math.floor(Math.random( ) * numFrames + 1);

gotoAndStop(randomFrame);   // Send playhead to chosen random frame

Example 2.7 determines the distance between two clips. A working version of this example is available from the online Code Depot.

Example 2-7. Calculate the Distance Between Two Movie Clips

var c;         // A convenient reference to the circle clip object
var s;         // A convenient reference to the square clip object
var deltaX;    // The horizontal distance between c and s
var deltaY;    // The vertical distance between c and s
var dist;      // The total distance between c and s

c = _root.circle;       // Get reference to the circle clip
s = _root.square;       // Get reference to the square clip
deltaX = c._x - s._x;   // Compute the horizontal distance between the clips
deltaY = c._ y - s._ y;   // Compute the vertical distance between the clips

// The distance is the root of (deltaX squared plus deltaY ...