Category Archives: random

Random Negative or Positive

By Zevan | June 17, 2009
CLICK HERE TO COPY
Actionscript:
  1. for (var i:int = 0; i<10; i++){
  2.   // randomly set a variable to -1 or positive 1
  3.   trace(int(Math.random()*2) - 1 | 1);
  4. }
  5.  
  6. /* outputs something like this
  7. 1
  8. 1
  9. -1
  10. 1
  11. -1
  12. -1
  13. 1
  14. 1
  15. -1
  16. -1
  17. */

The past few days I found myself using this one-liner a few times. Just a quick way to randomly get -1 or 1.

I was brainstorming today and wrote a weird/bad inline version of an old post:

var rand:Number = [-3, 2, 1, 1, 1, 0.5][int(Math.random() * 6)];

I need to install a related posts plugin for WordPress - would be nice if this post were related to my old post about Tausworthe random seeds.

Been posting medium/large snippets and snippets the relate to QuickBox2D - so today I figured I'd get back to basics...

Also posted in one-liners | Tagged , , | 3 Comments

Unique ID

By Zevan | December 17, 2008
CLICK HERE TO COPY
Actionscript:
  1. trace((new Date()).getTime() + Math.random()*0xFFFFFF);

A hacky way to get a unique ID, although this isn't, perfect it works well enough. For a project that you really expect to get huge amounts of traffic... you might consider using php's uniqid() function and passing it into your swf. That said, the odds of two users getting the same two ID values are about as good as the odds of you winning the lottery twice in a row.

Here is a version wrapped in a function, with a prefix argument:

CLICK HERE TO COPY
Actionscript:
  1. trace(uniqid("z"));
  2.  
  3. function uniqid(prefix:String):String{
  4. return prefix + (new Date()).getTime() + Math.random()*0xFFFFFF;
  5. }

Also posted in misc, one-liners | Tagged , | Leave a comment

Simple Particles

By Zevan | November 25, 2008
CLICK HERE TO COPY
Actionscript:
  1. stage.frameRate = 30;
  2. addEventListener(Event.ENTER_FRAME, onLoop);
  3. function onLoop(evt:Event):void{
  4.     if (int(Math.random()*5)==1){
  5.       for (var i:int= 0; i<10; i++) createParticle();
  6.     }
  7. }
  8.  
  9. function createParticle():void{
  10.     var s:MovieClip = new MovieClip();
  11.     s.graphics.beginFill(0);
  12.     s.graphics.drawCircle(0,0,Math.random()*10 + 2);
  13.     s.velX = Math.random()*10-5
  14.     s.velY =  Math.random()*10-5
  15.     s.posX = s.x = 200;
  16.     s.posY = s.y = 200;
  17.     addChild(s);
  18.     s.addEventListener(Event.ENTER_FRAME, onRunParticle);
  19. }
  20.  
  21. function onRunParticle(evt:Event):void {
  22.     var s:MovieClip = MovieClip(evt.currentTarget);
  23.     s.posX += s.velX;
  24.     s.posY += s.velY;
  25.     s.scaleX = s.scaleY -=  .04;
  26.     if (s.scaleX <0){
  27.         removeChild(s);
  28.         s.removeEventListener(Event.ENTER_FRAME, onRunParticle);
  29.     }
  30.     s.x = s.posX;
  31.     s.y = s.posY;
  32. }

Nothing special here. But my students are always asking me about this - in class I have them alter this code to make fire, water and abstract particle systems.

Also posted in motion | Tagged , , , | 6 Comments

Random Choice

By Zevan | November 2, 2008
CLICK HERE TO COPY
Actionscript:
  1. function randomChoice(...args:Array):*{
  2.     return args[int(Math.random()*args.length)];
  3. }
  4.  
  5. // choose randomly from a number of different values
  6. var val:* = randomChoice(10, "Hello", "0xFF0000", 1000);
  7.  
  8. // choose a random color (in this case red, green or blue)
  9. var randColor:uint = randomChoice(0xFF0000, 0x00FF00, 0x0000FF);
  10.  
  11. trace(val);
  12. trace(randColor);

The function randomChoice() takes any number of arguments and spits one of them back randomly. Just a handy function to have around... I especially like to use this function to choose from a handful of colors.

Also posted in functions | 2 Comments