JS1k: The JavaScript code golfing competition

_='setInterval(rn,337pG,lG,H=3,mx,my,ck,U=-1,dsmove$mx%X;my%Y}down$ck_Qmx,my)F(U=i)}up$ck;U=-1};
 gl(H++;pG;lGpLx:Cy:y=D})k=i+1lLf:i,:k}7k=4i=kidd,fgAb9;bAbmAe9;eAehAd9;dAdnAf9;fAf@; 0>((fzme(fzgb)F0>(qbhdqbnf)?0:1did,f(bzb-d)+qfe-f)dtdd;;8arc15,0,67Vda(8lineWid`=2;Oc,,8mov^f9jf@),8lin^9j@),OVch(s_kKN,p)if(i!=kFQk9jk@)KZ;s;break}cNl)i==kfJfJfJJf||id(lf,l,f,)||(lcZ,s7 srn("#aaa";Rect(0,0,CD7ckF-1<UF(U9=mxjU@=my7chVFglVdtK7da(71E3<ds++F(ds,)};
function[i	l[k	Ma`.randomV*for(;i<H;i++)l.splice(~~(l.leng`),1) in 	].(px,pyjp[8fill)*(;onmouse-h)/(n-h+.1)+d--g)/(m-g+.1)+b-var (b,e,8beginPa`V){;i}
 returnStyle=;k<H;k++)||l=0tokl)$=
(b%=b.client7);8c.9	x@	yA=Ca.wid`,Da.heightF&&G=[]HlvlJ==KpclL.push({N="Blue"O8strokeQ400>diUdpV()Z="Red"^eTo(_=1p)`thj,q(e-z-d@;';for(Y in $='zqj`_^ZVUQONLKJHGFDCA@987%$	
')with(_.split($[Y]))_=join(pop());eval(_)

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

setInterval(run, 33);
var points=[];
var links=[];
var level=3;
var mx;
var my;
var clicked=false;
var draggingPoint=-1;
var desperation=0;
a.addEventListener("mousemove", function (e) { mx=e.clientX; my=e.clientY;});
a.addEventListener("mousedown", function (e) {
  clicked=true;
  for(i in points)
    if( distance(points[i].x, points[i].y,mx,my) < 400)
      draggingPoint=i;
      
});
a.addEventListener("mouseup", function (e) { clicked=false; draggingPoint=-1;});
function generateLevel()
{
  level++;
  points=[];
  links=[];
  //points
  for(i=0;i<level;i++)
    points.push({ x: Math.random()*a.width , y:y=Math.random()*a.height});
  //links
  for(i=0;i<level;i++)
    for(k=i+1;k<level;k++)
      links.push({from: i, to: k});
  //make it solvable, kinda.
  for(k=4;k<level;k++)
    for(i=k;i<level;i++)
      links.splice(~~(Math.random()*links.length),1)
}
function indipendenti(a,b,a1,b1)
{
  //console.log("Controllo "+a+"-"+b+"  con  "+a1+"-"+b1);
  var x = points[a].x;
  var y = points[a].y;
  var x1 = points[b].x;
  var y1 = points[b].y;
  var x2 = points[a1].x;
  var y2 = points[a1].y;
  var x3 = points[b1].x;
  var y3 = points[b1].y;
  //TRUST PAST ME.
  if (
    ((y3-y2) * (x1-x2) / (x3-x2+0.1) + y2 - y1) * 
    ((y3-y2) * (x-x2 ) / (x3-x2+0.1) + y2 - y ) < 0 
    && 
    ((y1-y)  * (x2-x) /  (x1-x +0.1) + y  - y2) * 
    ((y1-y)  * (x3-x) /  (x1-x +0.1) + y  - y3) < 0)
    return false;
  return true;
}
function distance(ax,ay,bx,by)
{
  return (ax-bx)*(ax-bx)+(ay-by)*(ay-by);
}
function drawPoint(x,y,color)
{
  c.fillStyle=color;
  c.beginPath();
  c.arc(x,y,15,0,6);
  c.fill();
}
function drawAllConnections()
{
  c.lineWidth=2;
  for(k in links)
  {
    c.strokeStyle=links[k].c;
    c.beginPath();
    c.moveTo(points[links[k].from].x,points[links[k].from].y);
    c.lineTo(points[links[k].to].x,points[links[k].to].y);
    c.stroke();
  }
  return;
}
//controlla e colora
function check()
{
  allSafe=true;
  //collisioni dei punti
  for(i in points)
  {
    points[i].color="Blue";
    for(k in points)
    {
      if(i==k)
        continue;
      if(distance(points[i].x,points[i].y,points[k].x,points[k].y)<400)
      {
        points[i].color="Red";
        allSafe=false;
        break;
      }
    }
  }
  //reset colori
  for(k in links)
    links[k].c="Blue";
  //collisioni dei link
  for(i in links)
    for(k in links)
    {
      if(i==k || links[i].from==links[k].from || links[i].to==links[k].to || links[i].from==links[k].to || links[i].to==links[k].from)
        continue;
      if(!indipendenti(links[i].from, links[i].to, links[k].from, links[k].to))
          {
            links[i].c="Red";
            //links[k].c="Red";
            allSafe=false;
          }
    }
  return allSafe;
}
function run()
{
	//draw the background
	c.fillStyle="Silver";
	c.fillRect(0,0,a.width,a.height);

  if(clicked && draggingPoint > -1)
  {
    points[draggingPoint].x=mx;
    points[draggingPoint].y=my;
  }
  if(check())
    generateLevel();
  //Draw the points
  for(i=0;i<level;i++)
    drawPoint(points[i].x,points[i].y,points[i].color);
    

  drawAllConnections();
  //if you are desperated, we make the game easier
  if(desperation++>1000)
  {
    desperation=0;
    links.splice(~~(Math.random()*links.length),1)
  }
}