Collision detection with javascript using interval tree

advanced_collision_detection.js

// Collision detection with javascript using semi-interval tree. 
// Add elements using insert function, then check collision using hasCollision.
	var collisionTree = {
		LEFT: 1,
		RIGHT: 0,
		INTERSECT: 2,
		nodes:null,
		margin: 1,
		init: function(margin){
			this.nodes = new Array();
			if(margin!=undefined) this.margin = margin;
		},
		insert: function(element){
			var node = {
				position:{
					top: parseInt(element.style.top),
					right: parseInt(element.style.left) + parseInt(element.style.width),
					bottom: parseInt(element.style.top) + parseInt(element.style.height),
					left: parseInt(element.style.left),
				},
				divisor: parseInt(element.style.left),
				id: element.id,
				left: null,
				right: null,
			};
			if(this.nodes.length == 0){
				this.nodes.push(node);
			}else{ 
				this.nodes[0] = this._pushDown(this.nodes[0],node);
			}
		},
		hasCollision: function(element){
			if(this.nodes.length == 0) return false;
			var node = {
				position:{
					top: parseInt(element.style.top),
					right: parseInt(element.style.left) + parseInt(element.style.width),
					bottom: parseInt(element.style.top) + parseInt(element.style.height),
					left: parseInt(element.style.left),
				},
			};
			return this._testCollision(this.nodes[0],node);
		},
		debug: function(){
			//console.log(this.nodes);
			this.traverseTree(this.nodes[0]);
		},
		_testCollision: function(root,node){
			if(this._checkCollision(root,node)){
				return true;
			}else{
				var result = this._test(root.divisor,node);
				switch(result){
					case this.LEFT:
						if(root.left == null)
							return false;
						else
							return this._testCollision(root.left,node);
						break;
					case this.RIGHT:
						if(root.right == null)
							return false;
						else
							return this._testCollision(root.right,node);
						break;
					case this.INTERSECT:
						var newNodes = this._splice(node,root.divisor);
						var hasCollision = false;
						if(root.right == null)
							hasCollision = false;
						else
							hasCollision = this._testCollision(root.right,newNodes.right);

						if(hasCollision) return true;

						if(root.left == null)
							hasCollision = false;
						else
							hasCollision = this._testCollision(root.left,newNodes.left);
						return hasCollision;
						break;
				}
			}
		},
		_checkCollision: function(node1,node2){
			var pos1 = node1.position;
			var pos2 = node2.position;
			return ( (pos1.left - this.margin) <= (pos2.right + this.margin) &&
				 (pos1.right + this.margin) >= (pos2.left - this.margin) &&
				 (pos1.top - this.margin) <= (pos2.bottom + this.margin) &&
				 (pos1.bottom + this.margin) >= (pos2.top - this.margin) 
			);
		},
		_pushDown: function(root,node){
			var result = this._test(root.divisor,node);
			switch(result){
				case this.LEFT:
					if(root.left == null)
						root.left = node;
					else
						root.left = this._pushDown(root.left,node);
					break;
				case this.RIGHT:
					if(root.right == null)
						root.right = node;
					else
						root.right = this._pushDown(root.right,node);
					break;
				case this.INTERSECT:
					var newNodes = this._splice(node,root.divisor);
					if(root.right == null)
						root.right = newNodes.right;
					else
						root.right = this._pushDown(root.right,newNodes.right);
					if(root.left == null)
						root.left = newNodes.left;
					else
						root.left = this._pushDown(root.left,newNodes.left);
					break;
			}
			return root;
		},
		_test: function(divisor,newNode){
			if( newNode.position.left < divisor && divisor < newNode.position.right ){
				return this.INTERSECT;
			}else if(divisor <= newNode.position.left) {
				return this.RIGHT;
			}else{
				return this.LEFT;
			}
		},
		_splice: function(node,divisor){
			var nodes = {
				left:{
					position:{
						left: node.position.left,
						top: node.position.top,
						right: divisor,
						bottom: node.position.bottom,
					},
					id: node.id+'-left',
					divisor: node.position.left,
					left: null,
					right: null,
				},
				right:{
					position:{
						left: divisor,
						top: node.position.top,
						bottom: node.position.bottom,
						right: node.position.right,
					},
					id: node.id+'-right',
					divisor: divisor,
					left: null,
					right: null,
				}
			};
			return nodes;
		},
		_traverseTree: function(root){
			if(root == null) return;
			var newElem = document.createElement('div');
			$(newElem).addClass('itemd').width(root.position.right-root.position.left+'px').height(root.position.bottom-root.position.top+'px').attr('id',root.id);
			$(newElem).appendTo('.debug');
			var sep1 = document.createElement('div');
			$(sep1).addClass('clearfix');
			$(sep1).appendTo('.debug');
			this.traverseTree(root.left);
			this.traverseTree(root.right);
			var sep = document.createElement('div');
			$(sep).addClass('clearfix');
			$(sep).appendTo('.debug');
		},
};