05.18.2009
I’ve created a quick demo with APE that allows the user to draw rectangle particles with the mouse. New wheel particles are created every 2 seconds. Particles are removed if they fall outside the stage area so that the demo will not leak memory.
Main.as:
package {
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.events.Event;
import flash.utils.Timer;
import flash.events.TimerEvent;
import org.cove.ape.*;
// Draw APE Rectangle Particles
// built with Actionscript Physics Engine v0.45
// http://www.cove.org/ape/
public class Main extends Sprite
{
private var myRectangle:RectangleParticle
private var wheel:WheelParticle;
private var defaultGroup:Group;
private var beginX:Number; // mouse drag top left x position
private var beginY:Number; // mouse drag top left y position
private var endX:Number; // mouse drag bottom right x position
private var endY:Number; // mouse drag bottom right y position
private const bound:Number = 600;
public function Main()
{
init();
}
private function init():void
{
stage.frameRate = 65;
// Initialize the engine. The argument here is the time step value.
// Higher values scale the forces in the sim, making it appear to run
// faster or slower. Lower values result in more accurate simulations.
APEngine.init(1/4);
APEngine.damping = 0.98;
// set the default diplay container
APEngine.container = this;
APEngine.addMasslessForce(new Vector(0,8));
defaultGroup = new Group();
defaultGroup.collideInternal = true;
//RectangleParticle(x, y, width, height, rotation, fixed, mass, elasticity, friction)
var floor:RectangleParticle = new RectangleParticle(300,490, 600, 20, 0.0, true, 10, 0.4, 0.55);
floor.setStyle(0, 0, 0, Math.random() * 0x111111);
defaultGroup.addParticle(floor);
APEngine.addGroup(defaultGroup);
addEventListener(Event.ENTER_FRAME, run);
stage.addEventListener(MouseEvent.MOUSE_DOWN, beginDrawRect);
stage.addEventListener(MouseEvent.MOUSE_UP, endDrawRect);
setTimer(); // start creating wheel particles
}
private function beginDrawRect(m:MouseEvent):void
{
beginX = mouseX;
beginY = mouseY;
}
private function endDrawRect(m:MouseEvent):void
{
endX = mouseX;
endY = mouseY;
// if we have 2 positive numbers, draw:
if (endX - beginX > 1 && endY - beginY > 1)
{
drawRectangle();
}
}
private function drawRectangle():void
{
//RectangleParticle(x, y, width, height, rotation, fixed, mass, elasticity, friction)
// the more area a rectangle has the more mass we give it:
myRectangle = new RectangleParticle(beginX + ( (endX - beginX)/2 ), beginY + ((endY - beginY)/2), endX - beginX, endY - beginY, 0 , false, (endX - beginX) * (endY - beginY) , 0.4, 0.1);
myRectangle.setStyle(0, 0, 0, Math.random() * 0xffffff);
defaultGroup.addParticle(myRectangle);
}
private function createParticle(e:TimerEvent):void
{
//WheelParticle(x, y, radius, fixed, mass, elasticity, friction, traction)
var rand:Number = Math.random();
// the more area a wheel has the more mass we give it:
wheel = new WheelParticle(rand * stage.stageWidth, -20, rand * 55, false, rand * 55, 0.4, 0.1);
wheel.setStyle(0, 0, 0, Math.round(Math.random() * 0xffffff));
defaultGroup.addParticle(wheel);
checkForBounds();
}
// Check location of particles & remove if out of bounds so that we don't leak memory:
function checkForBounds()
{
/* particles:Array [read-only] The Array of all AbstractParticle
instances added to the AbstractCollection */
for (var i:Number = defaultGroup.particles.length -1; i > 0 ; --i){
/* Check to see if particles is past the 'bound' number, if is then remove it from system
py & px give the X & Y location of the partical, view AbstractParticle in APE api */
if ( defaultGroup.particles[i].py > bound )
{
defaultGroup.removeParticle( defaultGroup.particles[i] ); // Removes an AbstractParticle from the AbstractCollection.
}
}
}
private function setTimer():void
{
var myTimer:Timer= new Timer(2000, 0);
myTimer.addEventListener("timer", createParticle);
myTimer.start();
}
private function run(e:Event):void
{
APEngine.step();
APEngine.paint();
}
}
}
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