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Creare un realistico effetto fumo con ActionScript 3

Posted on 26. Sep, 2009 by daniele in flash, tutorials

Questa classe permette di creare un effetto fumo davvero realistico. Nella directory dov'è localizzato il file .fla create una nuova cartella e rinominatela "script". Adesso aprite un editor di testo qualsiasi e copiate e incollate il seguente codice:

/*
*The smoke effect is achieved by creating small circles
*They are continuously moved upwards
*A BlurFilter is applied to make them look realistic
*As they float above their dimensions are increased and the alpha reduced
*Actually only 40 particles are present and they are continuosly
recycled to prevent the main memory occupied by the .swf file
from increasing.
*/

package script{

import flash.display.Sprite;
import flash.display.Shape;
import flash.display.MovieClip;
import flash.events.Event;
import flash.events.TimerEvent;
import flash.filters.BlurFilter;
import flash.utils.Timer;

public class Smoke extends Sprite
{
/*this will be the parent container*/
private var smoke_mc:MovieClip = new MovieClip();

/*color of the smoke*/
private var color:uint;

/*radius of each smoke particle*/
private var partRadius:Number = 1;

/*BlurFilter for the smoke particles*/
private var blur:BlurFilter = new BlurFilter(8,8,2);

/*timer to attach smoke particles*/
private var timer:Timer = new Timer(100);

/*
the constructor takes 3 parameters-
X and Y coordinates of the point of origination
and the color of the smoke
*/
public function Smoke(xc:Number,yc:Number,col:uint)
{
/*attach the parent movieClip*/
smoke_mc.x=xc;
smoke_mc.y=yc;
addChild(smoke_mc);

/*assign the color*/
color=col;

/*start the timer*/
timer.start();

/*listener for the timer. the function startSmoke
is called every 100 miliseconds*/
timer.addEventListener(TimerEvent.TIMER,startSmoke);
}

/*attaches one smoke particle to the stage*/
private function startSmoke(e:TimerEvent)
{
/*if 40 particles has been attached
stop attaching any more */
if(smoke_mc.numChildren>40)
{
/*stop the timer*/
timer.stop();

/*remove the timer listener*/
timer.removeEventListener(TimerEvent.TIMER,startSmoke);
}

/*atach a particle to the parent movieclip*/
smoke_mc.addChild(smokeParticle());
}

/*Create and return a fully formed smoke particle*/
private function smokeParticle():Sprite
{
var smokePart:Sprite = new Sprite();

smokePart.graphics.beginFill(color);

/*create the particle at a random point
between +2 and -2 pixels from the given
X coordinate*/
var randX = -2+Math.random()*4;
smokePart.graphics.drawCircle(randX,0,partRadius);

smokePart.graphics.endFill();

/*blur the particle*/
smokePart.filters=[blur];

/*add more randomness to the X coordinate*/
var randDist = -10+Math.random()*20;
smokePart.x+=randDist;

/*move the particles*/
smokePart.addEventListener(Event.ENTER_FRAME,moveUp);

return smokePart;
}

/*
move and resize the particles
change the values to see their
effects on the smoke
*/
private function moveUp(e:Event)
{
/*if the particle is visible*/
if(e.currentTarget.alpha>0)
{
/*move it upwards*/
e.currentTarget.y-=1;

/*increase the width*/
e.currentTarget.width+=0.5;

/*incraese the height at a lesser rate*/
e.currentTarget.height+=0.3;

/*reduce the alpha*/
e.currentTarget.alpha-=.004;
}
/*if the particle is not visible
restore Y to 0 ,X to a random
value, width and height to the
original radius and the alpha to 1*/
else
{
e.currentTarget.y=0;

var randDist = -5+Math.random()*10;
e.currentTarget.x+=randDist;

e.currentTarget.width=partRadius;

e.currentTarget.height=partRadius;

e.currentTarget.alpha=1;
}
}
}
}

Adesso salvate il file col nome "Smoke.as", aprite il vostro file flash e premete Ctrl+J, impostate la larghezza e l'altezza a 200 x 300, premete F9 e nella finestra delle azioni copiate e incollate il seguente codice:

/*import the custom class*/
import script.Smoke;

/*call the constructor to create a new instance of the Smoke class
change the X and Y coordinates and the Color of the smoke here.
*/
var smoke:Smoke=new Smoke(100,150,0xBBBBBB);

/*add the instance to the stage*/
addChild(smoke);

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