Rain Particle Generator

FLASH CLASSES IMPORT
TWEENER IMPORT

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license : All rights reserved
modified : 2009-02-06 14:39:38

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package {
    //	FLASH CLASSES IMPORT
	
	import flash.events.*;
	import flash.display.*;
	import flash.utils.*;
	
	// TWEENER IMPORT
	
	import caurina.transitions.Tweener;

[SWF(backgroundColor="#000000", frameRate=30)]
		
	
	public class Rain extends MovieClip {
		
		
		private var nXDif:Number;          		// x offset based on angle and length
		private var nYDif:Number;          		// y offset based on angle and length
		
		private var iRotDegrees:int;       		// angle to rotate rain clip
		private var nRotRadians:Number;    		// same angle in radians (calculated based on iRotDegrees);
		private var iRotVariance:int;     		// number of randomness offset angle (degrees) to apply to general angle or raindrops. 10 will go +5 or -5 either way
		private var iLen:int            		// length the rain is going to travel
		
		private var iTime:int;             		// call rainTimerHandler every iTime milliseconds...
		private var iDrops:int;         		// new drops to add each time Rain timer is called
		
		private var iDropLengthMin:int;    		// min size of rain
		private var iDropLengthRnd:int;      	// random length of new rain drops to add on to min size
		private var iDropStroke:int;            // stroke width of rain drop
		private var iDropColor:uint;          	// color of rain stroke
		private var iDropAlpha:int;        		// alpha of drop stroke - 0 to 1
		private var iYOffSetStart:int;       	// start new rain drops this y offset so they come on
		private var iYOffSetRnd:int;       		// start new rain drops this y offset so they come on
		
		private var nSpeed:Number;           	// speed in seconds rain takes to fall distance
		private var nSpeedVariance:Number;		// speed variance - will go +1 or -1 either way....
		
		private var __displayList:Array;
		
		
		// 	timer
		private var tRainTimer:Timer;

//	Construct
		function Rain() {
			
			initVars();
			addEventListener(Event.ADDED_TO_STAGE, attach);
			
		}
		
		
		
		private function initVars() : void {
			
			__displayList = new Array(); // in case we want to make a list of all rain objects and loop through and remove when kill function is called.
			
			iRotDegrees         = 100;
			nRotRadians     	= iRotDegrees * Math.PI/180;
			iRotVariance        = 10;
			iLen                = 1400;
			iTime               = 15;
			iDrops              = 12;
			iDropLengthMin  	= 5;
			iDropLengthRnd      = 50;
			iDropStroke         = 1.5;
			iDropColor         	= 0xcccccc;
			iDropAlpha          = 1;
			iYOffSetStart       = -50;
			iYOffSetRnd         = 100;
			nSpeed           	= 1.5;
			nSpeedVariance 		= 1.5;
			
		}
		
		
		
		private function attach(e:Event) : void {
			
			trace("Rain Added");
			
			removeEventListener(Event.ADDED_TO_STAGE, attach);
			
			// 	timer
			tRainTimer = new Timer(iTime, 0); // this means the a new drop is added every (iTime) milliseconds approximately
			tRainTimer.addEventListener(TimerEvent.TIMER, rainTimerHandler);
			
			//rainDelayStart();

// just start the rain and have running constantly for this demo
                        tRainTimer.start();
			
			
		}
		
		
		// 	========================================================================
		
		
		//	PUBLIC & PRIVATE METHODS
                //      this method is used for making the rain start and stop periodically rather than running constantly
		
		private function rainDelayStart() : void
		{
			
			var nStartDelay:Number = Math.random() * 25000;
			var nDuration:Number   = 5000 + (Math.random() * 35000);
			
			setTimeout(function():void{tRainTimer.start();}, nStartDelay);
			setTimeout(function():void{
								 tRainTimer.stop();
								 rainDelayStart();}, nStartDelay + nDuration);
			
			
		}
		
		
		private function addRain() : void {

var tRotDegrees:Number 	= iRotDegrees + (Math.random() * iRotVariance) - iRotVariance/2; // angle to rotate rain clip
			var tRotRadians:Number 	= tRotDegrees * Math.PI/180;	// same angle in radians (calculated based on iRotDegrees);
			
			// create new blank sprite to draw into
			var sRain:Sprite = new Sprite();
			
			// lineStyle(width, color, alpha, hinting);
			sRain.graphics.lineStyle(iDropStroke, iDropColor, iDropAlpha, false);
			sRain.graphics.moveTo(0,0);
			
			// draw rain line - random x from 0 to 100 pixels long, y at zero - based on this being rotation of zero which is horizontal facing right
			sRain.graphics.lineTo(iDropLengthMin + (Math.random() * iDropLengthRnd), 0);
			
			// add rain anywhere between - stage width (stage left minus the width again) and + stage width (stage right)
			sRain.x 			= stage.stageWidth/2 + ((Math.random() * (stage.stageWidth * 2)) - stage.stageWidth);
			sRain.y 			= iYOffSetStart + (Math.random() * iYOffSetRnd);
			sRain.rotation 		= tRotDegrees;
			
			// add to root (or container if you have one)
			addChild(sRain);
			
			// calc the offset based on the angle and distance to travel
			nXDif = iLen * Math.cos( tRotRadians );
			nYDif = iLen * Math.sin( tRotRadians );
			
			
			// move it!
			Tweener.addTween(sRain, {alpha:0, x:sRain.x + nXDif, y:sRain.y + nYDif, time:nSpeed + ((Math.random() * nSpeedVariance) - nSpeedVariance/2), transition:"Linear", onComplete:function():void{ 
																																
										// delete this at end of tween and remove from memory
										removeChild(this);
										
																																  
																																  }});
		}
		
		
		//	========================================================================

//	EVENTS
		
		private function rainTimerHandler (e:TimerEvent) : void {
			
			// each time the timer is called - you can add as many drops as you want. this example adds 3 new drops;
			
			for (var iDrop:int = 0; iDrop < iDrops; iDrop++) {
				
				addRain();
				
			}
			
			
		}
		
		public function kill() : void {
			
			tRainTimer.stop();
			tRainTimer.removeEventListener(TimerEvent.TIMER, rainTimerHandler);
			
		}
		
		//	========================================================================
		
		//	GETTER & SETTER
		
		
	}
}

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