A pre release of my JavaScript physics engine, I will release it when I am happy

Physics.js

/*
 Physics MooTools plugin v1.0.0 pre release

 Licenced under GPL v3 (see README.md)
 Copyright 2011 - Oliver Caldwell (olivercaldwell.co.uk)
*/
var Physics={World:new Class({Implements:[Events,Options],options:{fps:16,width:500,height:500},initialize:function(e){e&&this.setOptions(e);this.interval=!1;this.clear=function(){var a=null,b=null;this.particles=[];this.positions=[];for(a=0;a<this.options.width;a+=1)for(b=0;b<this.options.height;b+=1)this.positions[a]=[],this.positions[a][b]=!1;return this};this.start=function(){this.interval===!1?(this.interval=setInterval(this.step,1E3/this.options.fps),this.fireEvent("start")):this.fireEvent("alreadyRunning");
return this}.bind(this);this.stop=function(){this.interval!==!1?(clearInterval(this.interval),this.interval=!1,this.fireEvent("stop")):this.fireEvent("notRunning");return this}.bind(this);this.moveParticle=function(a,b){this.positions[a.options.position.x][a.options.position.y]=!1;this.positions[b.x][b.y]=a;a.options.position=b;return this}.bind(this);this.applyFriction=function(a,b){a.options.velocity[b]!==0&&(a.options.velocity[b]-=a.options.velocity[b]/a.options.weight);a.options.velocity[b]>-0.01&&
a.options.velocity[b]<0.01&&(a.options.velocity[b]=0);return this}.bind(this);this.slideParticle=function(a,b){var e=a.options.position,g={x:b.x-e.x,y:b.y-e.y},j=g.x.abs()>=g.y.abs()?g.x.abs():g.y.abs(),g={x:g.x/j,y:g.y/j},c={},h={},d=null,f=null;for(i=1;i<=j;i+=1)if(c.x=(e.x+g.x*i).floor(),c.y=(e.y+g.y*i).floor(),c.x>=0&&c.y>=0&&c.x<this.options.width&&c.y<this.options.height)if(this.positions[c.x][c.y]){h.particle=!0;break}else d={x:c.x,y:c.y};else{h.wall=!0;break}if(d){this.moveParticle(a,d);if(h.particle){f=
this.positions[c.x][c.y];if(f.options.position.x<d.x||f.options.position.x>d.x)f.options.locked||(f.options.velocity.x+=a.options.velocity.x),a.options.velocity.x=0;if(f.options.position.y<d.y||f.options.position.y>d.y)f.options.locked||(f.options.velocity.y+=a.options.velocity.y),a.options.velocity.y=0;this.fireEvent("collision",[a,f])}if(h.wall){if(d.x===0||d.x===this.options.width-1)a.options.velocity.x=0;if(d.y===0||d.y===this.options.height-1)a.options.velocity.y=0;this.fireEvent("wallCollision",
[a])}}return this}.bind(this);this.step=function(){this.particles.each(function(a){a.options.locked||(a.options.gas?a.options.velocity.y-=a.options.weight:a.options.velocity.y+=a.options.weight,this.applyFriction(a,"x"),this.applyFriction(a,"y"),this.slideParticle(a,{x:(a.options.position.x+a.options.velocity.x).floor(),y:(a.options.position.y+a.options.velocity.y).floor()}))}.bind(this));this.fireEvent("step",[this.particles]);return this}.bind(this);this.addParticle=function(a,b){!this.positions[a.options.position.x][a.options.position.y]||
b?(this.particles.push(a),this.positions[a.options.position.x][a.options.position.y]=a,this.fireEvent("addParticle",[a])):this.fireEvent("inUse",[a,this.positions[a.options.position.x][a.options.position.y]]);return this}.bind(this);this.removeParticle=function(a){var b=this.particles.indexOf(a);b!==-1?(this.particles.splice(b,1),this.positions[a.options.posision.x][a.options.posision.y]=!1,this.fireEvent("removeParticle",[a])):this.fireEvent("noParticle",[a]);return this}.bind(this);this.clear();
this.start()}}),Particle:new Class({Implements:[Options],options:{position:{x:0,y:0},velocity:{x:0,y:0},weight:3,gas:!1,locked:!1},initialize:function(e){e&&this.setOptions(e)}})};