Creating Falling Snow in AS3/Flash - actionscript-3

Question

So I am trying to create random, falling snow in a Flash application. Using the following code I have my snow appearing at a random point on the screen.
var mc:snowFalling = new snowFalling();
addChild(mc);
var result:Number = Math.random() * 100;
var randomX:Number = Math.random() * stage.stageWidth;
mc.x = randomX;
snowFalling is the linkage name.
I am unsure how to have the snow both appear multiple times and respawn. Could someone give me a rundown of the code I will need to do this.

Answer 1

First, you need to create as many snowflakes on the screen as you'd like to have. Then, you need to move each snow flake every frame tick. Something like the following is ONE way you could do it. (there are many ways to accomplish this).
var flakes:Vector.<snowFalling> = new Vector.<snowFalling>(); //an array to store all your snow flakes
var mc:snowFalling;
var mc2:snowFalling;
var columns:int = 5;
var rows:int = 7;
var columnWidth:Number = stage.stageWidth / columns;
var rowHeight:Number = stage.stageHeight / rows;
//make 5 columns
for (var i:int = 0; i < columns; i++) {
mc = new snowFalling();
mc.x = (columnWidth * i);// + (Math.random() * (columnWidth * .25)); //to randomize the x position within the column size
addChild(mc);
flakes.push(mc);
//make 7 rows in each column
for (var j:int = 0; j < rows; j++) {
mc2 = new snowFalling();
mc2.x = mc.x;
mc2.y = (rowHeight * j);// + (Math.random() * (rowHeight * .25)); //to randomize the y within the row size
addChild(mc2);
flakes.push(mc2);
}
}
//run the enterFrame function below every frame tick of the application
this.addEventListener(Event.ENTER_FRAME, enterFrame);
function enterFrame(e:Event):void {
//loop through each snowflake in the flakes array
for (var i:int = 0; i < flakes.length; i++) {
flakes[i].y += 2; //move it down 2 pixels
//check to see if it's off screen, if so, move back to the top of the screen (less it's height so it's just off screen at the top)
if (flakes[i].y > stage.stageHeight) flakes[i].y = -flakes[i].height;
}
}
Or, if you wanted a traditional spawn type method, this:
//create a container to hold all the snowflakes
var snowContainer:Sprite = new Sprite();
addChild(snowContainer);
//this function creates a snowflake and puts it at the top of the screen in a random x spot
function spawnFlake(e:Event = null):void {
var mc:snowFalling;
snowContainer.addChild(mc);
mc.x = Math.random() * (stage.stageWidth - mc.width);
mc.y = -mc.height; //just off screen at the top
}
//create a timer that will call the spanFlake function every second
var timer:Timer = new Timer(1000);
timer.addEventListener(TimerEvent.TIMER, spawnFlake);
timer.start();
this.addEventListener(Event.ENTER_FRAME, enterFrame);
//every frame, iterate through all the children of snowContainer and move the flakes down 2 pixels
function enterFrame(e:Event):void {
var flake:snowFalling;
var i:int = snowContainer.numChildren;
//we need to iterate backwards because we are potentially removing items (which would throw our i value out of whack if iterating forwards)
while(i--){
flake = snowContainer.getChildAt(i) as snowFalling;
flake.y += 2;
//if out of bounds, remove the flake
if (flake.y > stage.stageHeight) {
snowContainer.removeChild(flake);
}
}
}