var mycode = function(){
  var msg1 = document.getElementById('msg1'),
      msg2 = document.getElementById('msg2'),
      msg3 = document.getElementById('msg3');

  //define variables
  var pad = scrawl.pad.mycanvas,
      ticker = Date.now(), 
      dTime = 0, 
      sTime = 0,
      timeSpeed = 25,
      rope,
      calculatePositions;

  //define sprites
  rope = scrawl.makePath({
    name: 		'rope',
    lineWidth: 	10,
    lineJoin: 	'round',
    lineCap: 	'round',
    data: 		'm0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0 0,0',
    markStart: 	'pin',
    mark: 		'joint',
    precision:	1,
  });

  scrawl.newWheel({
    name: 		'joint',
    radius: 	3,
    fillStyle: 	'gold',
    visibility:	'false',
  });

  scrawl.newWheel({
    name: 		'pin',
    method: 	'fillDraw',
    radius: 	10,
    fillStyle:	'red',
    lineWidth: 	2,
    visibility:	'false',
  });

  //define physics objects
  for(var i = 0; i < 20; i++){							//define particles for animating rope
    scrawl.newParticle({
      name: 	'b_'+i,
      startX:	300+(i * 15),
      startY:	100,
      mass: 	50,
      radius:	0.1,
    }).addForce('gravity');
    scrawl.point['rope_p'+(i + 1)].fixed = 'b_'+i;		//assign rope points to particle objects
  }
  scrawl.sprite.b_0.set({									//fix top of rope to display
    mobile: false,
  });

  for(var i = 0; i < 19; i++){							//add in springs between particles
    scrawl.sprite['b_'+i].addSpring({
      end:			'b_'+(i + 1),
      springConstant:	8000,
    });
  }

  //physics update function
  calculatePositions = function(){
    //update time
    var now = Date.now();
    sTime =  now - ticker;
    ticker = now;
    dTime = (sTime > timeSpeed) ? timeSpeed : sTime;
    scrawl.physics.deltaTime = dTime/1000;
    //calculate springs
    scrawl.updateSprings();
    //calculate particle positions and display results
    pad.render();
  };

  //animation object
  scrawl.newAnimation({
    fn: function(){
      calculatePositions();

      msg1.innerHTML = 'Milliseconds per physics refresh: '+parseInt(dTime);
      msg2.innerHTML = 'Milliseconds per screen refresh: '+parseInt(sTime);
      msg3.innerHTML = 'Frames per second: '+parseInt(1000/sTime);
    },
  });
};

scrawl.loadModules({
  path: 'http://scrawl.rikweb.org.uk/js/',
  modules: ['animation', 'path', 'wheel', 'physics'],
  callback: function(){
    window.onload = function(){
      scrawl.init();
      mycode();
    };
  },
});