Hi!
I’m trying to understand a particular couple of lines of code.
A couple of members here have helped me some so far (much appreciated!).
The code is an AS3 carousel - adapted from Lee Brimelow by Matbury @ actionscript.org.
(I`ve included complete AS3 code at the end of this post.)
I understand the idea of the for Loop - and that it is applying variables to an object created from the class shown below, but where I’m stumped is what the following line…
item.angl = i*((Math.PI*2) / numOfItems);
…means and HOW it relates in particular to the variable angl:Number in the class:
package {
public class Item extends ItemInner {
public var angl:Number;
public function Item() {
//
}
}
}
Anyone explain this briefly?
Thanks for any help - most impressed with the knowledge here & the willingness to share it.
My next step is Moock`s Essential AS3 - got a feeling that will help me a lot with things of this complexity.
Regards, Galland
/*
The ‘reflections’ will only work if ‘bitmap caching’ for the Icon
instance ‘ref’ and the ‘masker’ instance is turned on in the properties panel.
/
var numOfItems:uint = 5; // number of Items to put on stage
var radiusX:uint = 250; // width of carousel
var radiusY:uint = 75; // height of carousel
var centerX:Number = 560; // x position of center of carousel
var centerY:Number = 320; // y position of center of carousel
var speed:Number = 0.05; // initial speed of rotation of carousel
var itemArray:Array = new Array(); // store the Items to sort them according to their ‘depth’ - see sortBySize() function.
init();
// place Items on stage
function init():void {
for(var i:uint = 0; i < numOfItems; i++) {
var item:Item = new Item();
// public var angl:Number; is in Item class.
// Item class extends ItemInner in FLA library.
item.angl = i * ((Math.PI * 2) / numOfItems);
item.ref.mask = item.masker;
item.alpha = 0.5;
itemArray.push(item);
addChild(item);
item.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
// listen for MouseEvents only on icons, not on reflections
item.icon.addEventListener(MouseEvent.CLICK, clickHandler);
item.icon.addEventListener(MouseEvent.ROLL_OVER, rollOverHandler);
item.icon.addEventListener(MouseEvent.ROLL_OUT, rollOutHandler);
}
}
// position Items in elipse
function enterFrameHandler(event:Event):void {
event.target.x = Math.cos(event.target.angl) * radiusX + centerX; // x position of Item
event.target.y = Math.sin(event.target.angl) * radiusY + centerY; // y postion of Item
// scale Item according to y position to give perspective
var s:Number = event.target.y / (centerY + radiusY);
event.target.scaleX = event.target.scaleY = s;
event.target.angl += speed; // speed is updated by mouseMoveHandler
sortBySize();
}
// set the display list index (depth) of the Items according to their
// scaleX property so that the bigger the Item, the higher the index (depth)
function sortBySize():void {
// There isn’t an Array.ASCENDING property so use DESCENDING and reverse()
itemArray.sortOn(“scaleX”, Array.DESCENDING | Array.NUMERIC);
itemArray.reverse();
for(var i:uint = 0; i < itemArray.length; i++) {
var item:Item = itemArray;
setChildIndex(item, i);
}
}
function clickHandler(event:MouseEvent):void {
// clean up your listeners before you do anything else to free up
// user’s CPU resources
for(var i:uint = 0; i < itemArray.length; i++) {
var item:Item = itemArray*;
item.removeEventListener(Event.ENTER_FRAME, enterFrameHandler);
item.icon.removeEventListener(MouseEvent.CLICK, clickHandler);
item.icon.removeEventListener(MouseEvent.ROLL_OVER, rollOverHandler);
item.icon.removeEventListener(MouseEvent.ROLL_OUT, rollOutHandler);
// optional:
removeChild(item);
// to replace the carousel again see reInit() function
}
// put your own code here.
}
function rollOverHandler(event:MouseEvent):void {
event.target.parent.alpha = 1;
}
function rollOutHandler(event:MouseEvent):void {
event.target.parent.alpha = 0.5;
}
addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
/*
Update the speed at which the carousel rotates accoring to the distance of the mouse from the center of the stage. The speed variable only gets updated when the mouse moves over the Item Sprites.
/
function mouseMoveHandler(event:MouseEvent):void {
speed = (mouseX - centerX) / 6000;
}
// click to put Items back on stage
rewButton.buttonMode = true;
rewButton.addEventListener(MouseEvent.CLICK, reInit);
// put items back on stage
function reInit(event:MouseEvent):void {
for(var i:uint = 0; i < itemArray.length; i++) {
var item:Item = itemArray;
item.alpha = 0.5;
addChild(item);
item.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
item.icon.addEventListener(MouseEvent.CLICK, clickHandler);
item.icon.addEventListener(MouseEvent.ROLL_OVER, rollOverHandler);
item.icon.addEventListener(MouseEvent.ROLL_OUT, rollOutHandler);
}
}
