var nDots = 7;
if (document.all&&window.print)
//document.body.style.cssText="overflow-x:hidden;overflow-y:hidden"
var Xpos = 0;
var Ypos = 0;

var DELTAT = .01;
var SEGLEN = 10;
var SPRINGK = 10;
var MASS = 1;
var GRAVITY = 50;
var RESISTANCE = 10;
var STOPVEL = 0.1;
var STOPACC = 0.1;
var DOTSIZE = 11;
var BOUNCE = 0.75;

var isNetscape = navigator.appName=="Netscape";
var followmouse = true;
var dots = new Array();
init();

function init()
{
    var i = 0;
    for (i = 0; i < nDots; i++) {
        dots[i] = new dot(i);
    }
    
    if (!isNetscape) {
    }
    
    // set positions
    for (i = 0; i < nDots; i++) {
        dots[i].obj.left = dots[i].X;
        dots[i].obj.top = dots[i].Y;
    }
    
    
    if (isNetscape) {
        startanimate();
    } else {
        setTimeout("startanimate()", 0);
    }
}



function dot(i) 
{
    this.X = Xpos;
    this.Y = Ypos;
    this.dx = 0;
    this.dy = 0;
    if (isNetscape) {	
        this.obj = eval("document.dot" + i);
    } else {
        this.obj = eval("dot" + i + ".style");
    }
}


function startanimate() {	
    setInterval("animate()", 20);
}


function setInitPositions(dots)
{
    var startloc = document.all.tags("LI");
    var i = 0;
    for (i = 0; i < startloc.length && i < (nDots - 1); i++) {
        dots[i+1].X = startloc[i].offsetLeft
            startloc[i].offsetParent.offsetLeft - DOTSIZE;
        dots[i+1].Y = startloc[i].offsetTop +
            startloc[i].offsetParent.offsetTop + 2*DOTSIZE;
    }

    dots[0].X = dots[1].X;
    dots[0].Y = dots[1].Y - SEGLEN;
}

function MoveHandler(e)
{
    Xpos = e.pageX;
    Ypos = e.pageY;	  
    return true;
}

function MoveHandlerIE() {
    Xpos = window.event.x + document.body.scrollLeft;
    Ypos = window.event.y + document.body.scrollTop;	  
}

if (isNetscape) {
    document.captureEvents(Event.MOUSEMOVE);
    document.onMouseMove = MoveHandler;
} else {
    document.onmousemove = MoveHandlerIE;
}


function vec(X, Y)
{
    this.X = X;
    this.Y = Y;
}

function springForce(i, j, spring)
{
    var dx = (dots[i].X - dots[j].X);
    var dy = (dots[i].Y - dots[j].Y);
    var len = Math.sqrt(dx*dx + dy*dy);
    if (len > SEGLEN) {
        var springF = SPRINGK * (len - SEGLEN);
        spring.X += (dx / len) * springF;
        spring.Y += (dy / len) * springF;
    }
}


function animate() {	
    var start = 0;
    if (followmouse) {
        dots[0].X = Xpos;
        dots[0].Y = Ypos;	
        start = 1;
    }
    
    for (i = start ; i < nDots; i++ ) {
        
        var spring = new vec(0, 0);
        if (i > 0) {
            springForce(i-1, i, spring);
        }
        if (i < (nDots - 1)) {
            springForce(i+1, i, spring);
        }
        
        // air resisitance/friction
        var resist = new vec(-dots[i].dx * RESISTANCE,
            -dots[i].dy * RESISTANCE);
        
        // compute new accel, including gravity
        var accel = new vec((spring.X + resist.X)/ MASS,
            (spring.Y + resist.Y)/ MASS + GRAVITY);
        
        // compute new velocity
        dots[i].dx += (DELTAT * accel.X);
        dots[i].dy += (DELTAT * accel.Y);
        
        // stop dead so it doesn't jitter when nearly still
        if (Math.abs(dots[i].dx) < STOPVEL &&
            Math.abs(dots[i].dy) < STOPVEL &&
            Math.abs(accel.X) < STOPACC &&
            Math.abs(accel.Y) < STOPACC) {
            dots[i].dx = 0;
            dots[i].dy = 0;
        }
        
        // move to new position
        dots[i].X += dots[i].dx;
        dots[i].Y += dots[i].dy;
        
        // get size of window
        var height, width;
        if (isNetscape) {
            height = window.innerHeight + document.scrollTop-20;
            width = window.innerWidth + document.scrollLeft-20;
        } else {	
            height = document.body.clientHeight + document.body.scrollTop-20;
            width = document.body.clientWidth + document.body.scrollLeft-20;
        }
        
        // bounce of 3 walls (leave ceiling open)
        if (dots[i].Y >=  height - DOTSIZE - 1) {
            if (dots[i].dy > 0) {
                dots[i].dy = BOUNCE * -dots[i].dy;
            }
            dots[i].Y = height - DOTSIZE - 1;
        }
        if (dots[i].X >= width - DOTSIZE) {
            if (dots[i].dx > 0) {
                dots[i].dx = BOUNCE * -dots[i].dx;
            }
            dots[i].X = width - DOTSIZE - 1;
        }
        if (dots[i].X < 0) {
            if (dots[i].dx < 0) {
                dots[i].dx = BOUNCE * -dots[i].dx;
            }
            dots[i].X = 0;
        }
        
        // move img to new position
        dots[i].obj.left = dots[i].X;			
        dots[i].obj.top =  dots[i].Y;		
    }
}

function PopUp(URL, w, h) {
	day = new Date();
	id = day.getTime();
	eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=' + w + ',height=' + h);");

}


function validate_form() {
  validity = true; 
  if (!check_empty(document.form.naam.value))
        { validity = false; alert('U heeft geen naam ingevuld!'); }
 
  if (!check_empty(document.form.straat_huisnummer.value))
        { validity = false; alert('U heeft geen straat + huisnr. ingevuld!'); }
        
  if (!check_empty(document.form.postcode_plaats.value))
        { validity = false; alert('U heeft geen postcode + plaats ingevuld!'); }
 
  if (!check_box(document.form.C2.checked))
        { validity = false; alert('U dient akkoord te gaan met de voorwaarden!'); }
 
  if (!check_email(document.form.email.value))
        { validity = false; alert('Het E-mail adres is ongeldig!'); }

return validity;
}

function check_empty(text) {
  return (text.length > 0); // returns false if empty
}

function check_box(mchecked) {
  if (mchecked == 0){
  	return false;
  }else{
  	return true;
	}
}

function check_email(adres) {
  if ((adres == "")
    || (adres.indexOf ('@') == -1)
    || (adres.indexOf ('.') == -1))
      return false;
  return true;
}