AS3 Polar Coordinates and Radians

Many times I’ve set up interfaces where I need to place different objects equidistant around a central object. The solution to this problem is to first calculate the angle of each object by converting Radians to Degrees. This can be expressed by the following formula

So, you simply need to loop through your collection of objects and assign each a different angle. After that you plug that angle into a new Polar Point.

for(var i=0;i<array.length;i++)
{
	var angle:Number = i*( 180/Math.PI )
	var coord:Point = Point.polar( circumference, angle )
}

Here’s the complete source: radians.zip

package
{
	import flash.ui.*;
	import flash.display.*;
	import flash.events.*;
	import flash.geom.*;

	public class Main extends Sprite
	{

		/*
		========================================================
		| Private Variables                         | Data Type
		========================================================
		*/

		private var array:Array = new Array()
		private var circumference:int;

		/*
		========================================================
		| Constructor
		========================================================
		*/

		public function Main ()
		{
			stage.align = StageAlign.TOP_LEFT;

			// make some balls
			addParticle( 100 )

			menu.txtParticles.text = 'Particles: 100';

			stage.addEventListener( Event.ENTER_FRAME, runParticle )

			menu.slideCircumference.addEventListener( Event.CHANGE, changeCircumference );
			menu.particles.addEventListener( Event.CHANGE, changeParticles );

		}

		private function addParticle( num )
		{
			stage.removeEventListener( Event.ENTER_FRAME, runParticle )

			var tot:Number = array.length

			// kill mc's
			for( var t=0;t<tot;t++ )
			{
				removeChild( array[t].mc );
			}

			// kill array
			for( var r=0;r<tot;r++ )
			{
				array.shift();
			}

			trace( 'removed particles '+array.length )

			for( var d=0;d<num;d++ )
			{
				var c:MovieClip = new MovieClip()
				c.name = "particle"
				c.graphics.beginFill( 0xffffff, 1 )
				c.graphics.drawCircle( 0, 0, 1 )
				c.graphics.endFill()
				addChild( c )

				array.push( { mc:c } )
			}

			trace( 'added particles '+array.length )

			changeCirc( circumference )

			stage.addEventListener( Event.ENTER_FRAME, runParticle )
		}

		private function runParticle( e:Event )
		{
			//trace( 'running' )
			graphics.clear()
			graphics.lineStyle( 1, 0xffffff, .1 )

			for(var i=0;i<array.length;i++)
			{
				graphics.moveTo( stage.stageWidth/2, stage.stageHeight/2 )
				graphics.lineTo( array[i].mc.x, array[i].mc.y )
			}

		}

		private function changeCirc( c:int )
		{
			for(var i=0;i<array.length;i++)
			{
				var angle:Number = i*( 180/Math.PI )
				var coord:Point = Point.polar( c, angle )

				array[i].mc.x = ( stage.stageWidth/2 ) + coord.x
				array[i].mc.y = ( stage.stageHeight/2 ) + coord.y
			}

			circumference = c
		}

		private function changeCircumference( e:Event ):void
		{
			menu.txtCircumference.text = 'Circumference: ' + e.target.value;
			changeCirc( e.target.value )
		}

		private function changeParticles( e:Event ):void
		{
			menu.txtParticles.text = 'Particles: ' + e.target.value;
			addParticle( e.target.value )
		}
	}
}

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