var psystem = new ParticleSystem();


psystem.setDamping(1.0);
psystem.setGravity(0.0, 0.4);

// cooefficient of restitution
psystem.setKfr(0.1);

// surface friction for particles
psystem.setFriction(0.5);


// surfaces
var sA = new Surface(new Point(0, 100), new Point(1, 300));
sA.setIsOrientH(false);
psystem.addSurface(sA);

var s0 = new Surface(new Point(1, 300), new Point(100, 300));
psystem.addSurface(s0);

var s1 = new Surface(new Point(100, 300), new Point(300, 300));
psystem.addSurface(s1);

var s2 = new Surface(new Point(300, 300), new Point(600, 350));
psystem.addSurface(s2);

var s3 = new Surface(new Point(600,350), new Point(799, 300));
psystem.addSurface(s3);

var sB = new Surface(new Point(799, 300), new Point(799, 100));
sB.setIsOrientH(false);
psystem.addSurface(sB);


// circle surface
var circA = new CircleSurface(300, 370, 100);
psystem.addSurface(circA);


var leftX = 10;
var rightX = 80
var widthX = rightX - leftX;
var midX = leftX + (widthX / 2);

var topY = 180;

// wheels
var wheelA = psystem.addWheel(leftX, topY, 25);
var wheelB = psystem.addWheel(rightX, topY, 25);
wheelA.coeffSlip = 0.0;
wheelB.coeffSlip = 0.0;

// body
var rectA = psystem.addRectangle(new Vector(midX, topY), widthX, 10);


// wheel struts
var conn1 = psystem.addConstraint(wheelA.wp, rectA.p3);
conn1.setRestLength(5);

var conn2 = psystem.addConstraint(wheelB.wp, rectA.p2);
conn2.setRestLength(5);

var conn1a = psystem.addConstraint(wheelA.wp, rectA.p0);
conn1a.setRestLength(5);

var conn2a = psystem.addConstraint(wheelB.wp, rectA.p1);
conn2a.setRestLength(5);


// triangle top of car
var p1 = psystem.addParticle(midX, topY - 50);
var conn3 = psystem.addConstraint(wheelA.wp, p1);
var conn4 = psystem.addConstraint(wheelB.wp, p1);


// angular constraint for triangle top
var ang = psystem.addAngularConstraint(wheelA.wp, p1, wheelB.wp);
var angDefault = ang.targetTheta;


// trailing body
var rectB = psystem.addRectangle(new Vector(midX, topY - 50), 10, 10);
var p2 = psystem.addParticle(midX, topY);
var conn3 = psystem.addConstraint(rectB.p1, p2);
conn3.setRestLength(20);
var conn4 = psystem.addConstraint(p1, p2);
conn4.setRestLength(20);

psystem.paintSurfaces();



this.onEnterFrame = function() {
	

	var keySpeed = 2.0;
	
	if(Key.isDown(Key.LEFT)) {
		wheelA.rp.vs = -keySpeed;
		wheelB.rp.vs = -keySpeed;
	} else if(Key.isDown(Key.RIGHT)) {
		wheelA.rp.vs = keySpeed;
		wheelB.rp.vs = keySpeed;
	} else {
		wheelA.rp.vs = 0;
		wheelB.rp.vs = 0;
	}

	if (Key.isDown(Key.UP)) {
		if (ang.targetTheta < 2.9) ang.targetTheta += .1;
	} else {
		if (ang.targetTheta > angDefault) ang.targetTheta -= .1;
	}

	psystem.timeStep();
	//psystem.paintParticles();
	psystem.paintWheels();
	psystem.paintConstraints();
	
}