manjav / hx-impulse-engine

HAXE port of a simple, open source, 2D impulse based physics engine for non-view (server-side) use.

Impulse Engine

Impulse Engine is a small 2D physics engine that originaly written in C++ by Randy Gaul. thanks to Philip Diffenderfer for java port. Impulse Engine is intended to be used in an educational manner by other looking to learn the inner workings of physics engines, but you can use in server-side and pure-logic projects.

TestSimple.hx class is demo of haxe-as3 language. based on your needs, build to cpp, java, js, cs, php and other haxe support languages.

Step 1 : Initialize impulse scene

this.impulse = new ImpulseScene(ImpulseMath.DT, 10);

Step 2 : Define static items

// center circle
var b:Body = null;
b = this.impulse.add(new Circle(30.0), 300, 500);
b.setStatic();

// bottom rectangle
var p = new Polygon();
p.setBox(250.0, 10.0);
b = this.impulse.add(p, 300, 600);
b.setStatic();
b.setOrient(0);

Step 3 : Instantiate circle, rectangle and polygon by click

this.stage.addEventListener(MouseEvent.CLICK, this.stage_clickHandler);

private function stage_clickHandler(event:MouseEvent):Void {
  var mx = Math.round(event.stageX);
  var my = Math.round(event.stageY);
  var min = 10;
  var max = 30;
  var b:Body;
  if (event.shiftKey) {
    var p = new Polygon();
    p.setBox(ImpulseMath.random(min, max), ImpulseMath.random(min, max));
    b = this.impulse.add(p, mx, my);
    b.setOrient(0.0);
  } else if (event.ctrlKey) {
    var r = ImpulseMath.random(min, max);
    var vertCount = ImpulseMath.randomR(3, Polygon.MAX_POLY_VERTEX_COUNT);
    var verts = Vec2.arrayOf(vertCount);
    for (i in 0...vertCount)
      verts[i].set(ImpulseMath.random(-r, r), ImpulseMath.random(-r, r));
    b = this.impulse.add(new Polygon(verts), mx, my);
    b.setOrient(ImpulseMath.random(-ImpulseMath.PI, ImpulseMath.PI));
    b.restitution = 0.2;
    b.dynamicFriction = 0.2;
    b.staticFriction = 0.4;
  } else {
    b = this.impulse.add(new Circle(ImpulseMath.random(min, max)), mx, my);
  }
}

Step 4 : Update every frames

this.addEventListener(Event.ENTER_FRAME, this.this_enterFrameHandler);
private function this_enterFrameHandler(event:flash.events.Event):Void {
  var t = Timer.stamp() * 1000;
  this.accumulator += (t - this.dt);
  this.dt = t;
  if (this.accumulator >= this.impulse.dt) {
    this.impulse.step();
    this.accumulator -= this.impulse.dt;
  }
}