A Graphics object draws circles and squares, but can also draw
more complex forms, particularly when the drawing methods are used
in combination with the properties and methods of the Math class.
The Math class contains constants of common mathematical interest,
such as
Math.PI
(approximately 3.14159265...),
a constant for the ratio of the circumference of a circle to its diameter.
It also contains methods for trigonometry functions, including
Math.sin()
,
Math.cos()
,
and
Math.tan()
among others. Drawing shapes using
these methods and constants create more dynamic visual effects, particularly
when used with repetition or recursion.
Many methods of the Math class expect circular measurements in
units of radians rather than degrees. Converting between these two
types of units is a common use of the Math class:
var degrees = 121;
var radians = degrees * Math.PI / 180;
trace(radians) // 2.111848394913139
The following example creates a sine wave and a cosine wave,
to highlight the difference between the
Math.sin()
and
Math.cos()
methods
for a given value.
var sinWavePosition = 100;
var cosWavePosition = 200;
var sinWaveColor:uint = 0xFF0000;
var cosWaveColor:uint = 0x00FF00;
var waveMultiplier:Number = 10;
var waveStretcher:Number = 5;
var i:uint;
for(i = 1; i < stage.stageWidth; i++)
{
var sinPosY:Number = Math.sin(i / waveStretcher) * waveMultiplier;
var cosPosY:Number = Math.cos(i / waveStretcher) * waveMultiplier;
graphics.beginFill(sinWaveColor);
graphics.drawRect(i, sinWavePosition + sinPosY, 2, 2);
graphics.beginFill(cosWaveColor);
graphics.drawRect(i, cosWavePosition + cosPosY, 2, 2);
}
