Computers and Programming Experiences

Flash Horizontal Starfield
Simple 4Kb Parallax Scrolling Starfield, the viewable version contains extra functionality to control the amount of Stars and Starfield Speed. On-screen diagnostics have been displayed as they may help influence any changes you decide to make.

The Starfield can be seen on my sister site Flash Experiences it can be found here Flash Horizontal Starfield.

import com.horizontalstarfield.Starfield;
 
var objStarfield:Starfield = new Starfield();
objStarfield.STAR_SPEED = 4;                  // By default this is currently set to 5.
 
addChild(this.objStarfield);

package com.horizontalstarfield
{
  import flash.events.*;
  import flash.display.*;
 
  /**
  * Name        : Starfield
  * Coded By    : Matt Wakeling
  * Date        : 20th November 2011
  * Description : Starfield Class for the main Starfield.
  *
  * @author Matt Wakeling
  */
  public class Starfield extends Sprite
  {
    // Intialise Class Properties
    private const START_STARS:int = 150;
    private const MINIMUM_ALPHA_PERCENT:int = 10;
    private const MAXIMUM_ALPHA_PERCENT:int = 100;
 
    public var STAR_SPEED:int = 5;
 
    // Starfield Constructor
    public function Starfield()
    {
      // Constructor Code
      super();
      this.InitialiseStarfield();
    }
 
    // InitialiseStarfield Method
    private function InitialiseStarfield():void
    {
      if (stage)
        this.InitialiseStage();
      else addEventListener(Event.ADDED_TO_STAGE, this.InitialiseStage);
    }
 
    // InitialiseStage Method
    private function InitialiseStage(e:Event = null):void
    {
      removeEventListener(Event.ADDED_TO_STAGE, this.InitialiseStage);
 
      var objStar:Star;
 
      var intLoopCounter:int = 1;
      while (intLoopCounter <= this.START_STARS)
      {
        objStar = new Star();
        objStar.x = (Math.random() * stage.stageWidth);
        objStar.y = (Math.random() * stage.stageHeight);
        objStar.alpha = ((Math.floor((Math.random() * ((this.MAXIMUM_ALPHA_PERCENT - this.MINIMUM_ALPHA_PERCENT) + 1))) + this.MINIMUM_ALPHA_PERCENT) / 100);
        objStar.STAR_SPEED = this.STAR_SPEED;
        addChild(objStar);
 
        objStar = undefined;
 
        intLoopCounter++;
      }
    }
  }
}
 

package com.horizontalstarfield
{
  import flash.display.Graphics;
  import flash.display.Sprite;
  import flash.events.Event;
 
  /**
  * Name        : Star
  * Coded By    : Matt Wakeling
  * Date        : 20th November 2011
  * Description : Star Class for the Starfield Class.
  *
  * @author Matt Wakeling
  */
  public class Star extends Sprite
  {
    // Intialise Class Properties
    private const MINIMUM_ALPHA_PERCENT:int = 10;
    private const MAXIMUM_ALPHA_PERCENT:int = 100;
 
    private var intStageWidth:int;
    private var intStageHeight:int;
 
    public var STAR_SPEED:int = 5;
 
    // Star Constructor
    public function Star()
    {
      // Constructor Code
      super();
      this.InitialiseStar();
    }
 
    // Initialise Method
    private function InitialiseStar():void
    {
      // Initiailise Stage
      if (stage) this.InitialiseStage();
      else addEventListener(Event.ADDED_TO_STAGE, InitialiseStage);
    }
 
    // InitialiseStage Method
    private function InitialiseStage(e:Event = null):void
    {
      removeEventListener(Event.ADDED_TO_STAGE, InitialiseStage);
 
      this.intStageWidth = stage.stageWidth;
      this.intStageHeight = stage.stageHeight;
 
      // Draw Star
      this.graphics.clear();
      this.graphics.beginFill(0xFFFFFF);
      this.graphics.drawCircle(0, 0, 1);
 
      addEventListener(Event.ENTER_FRAME, FrameEvent);
    }
 
 
    // FrameEvent Method
    private function FrameEvent(e:Event):void
    {
      this.x -= alpha * STAR_SPEED;
 
      if (this.x < 0)
      {
        this.x = this.intStageWidth;
        this.y = Math.random() * intStageHeight;
        alpha = ((Math.floor(Math.random() * (this.MAXIMUM_ALPHA_PERCENT - this.MINIMUM_ALPHA_PERCENT + 1)) + this.MINIMUM_ALPHA_PERCENT)/100);
      }
    }
  }
}