Range =  function () {

this.initialize.apply(this, arguments);

}

Range.prototype = function () {};

Range.prototype.constructor = Range;

Range.prototype.initialize = function (start, stop) {

this.start = start;

this.stop = stop;

}

Range.prototype.containValue = function (value) {

return value >= this.start && value <= this.stop;

}

Range.prototype.intersects = function (range) {

return !(this.stop < range.start || this.start > range.stop);

}

AABB = function () {

this.initialize.apply(this, arguments);

}

AABB.prototype = Rectangle;

AABB.prototype.constructor = AABB;

AABB.prototype.initialize = function (x, y, width, height) {

Rectangle.prototype.initialize.call(this, x, y, width, height);

this.setCencter();

this.setCorners();

this.setRange();

}

AABB.prototype.setCencter = function () {

this._cencter = new Point(this.x / 2, this.y / 2);

}

AABB.prototype.setCorners = function () {

this._leftUpPoint = new Point(this.x, this.y);

this._rightUpPoint = new Point(this.x + this.width, this.y);

this._leftDownPoint = new Point(this.x, this.y + this.height);

this._rightDownPoint = new Point(this.x + this.width, this.y + this.height);

}

AABB.prototype.setRange = function () {

this._wRange = new Range(this.x, this.x + this.width);

this._hRange = new Range(this.y, this.y + this.height);

}

AABB.prototype.getCenter = function () {

return this._cencter;

}

AABB.prototype.getCorners = function () {

return [this._leftUpPoint, this._rightUpPoint, this._leftDownPoint, this._rightDownPoint];

}

AABB.prototype.intersects = function (aabb) {

return this._wRange.intersects(aabb._wRange) && this._hRange.intersects(aabb._hRange);

}

AABB.prototype.containPoint = function (point) {

return point.x >= this.x && point.x <= this._rightDownPoint.x && point.y >= this.y && point.y <= this._rightDownPoint.y;

}

AABB.prototype.merge = function (aabb) {

var x = Math.min(this.x, aabb.x);

var y = Math.min(this.y, aabb.y);

var width = Math.max(this.x + this.width, aabb.x + aabb.width) - x;

var height = Math.max(this.y + this.height, this.y + aabb.height) - y;

return new AABB(x, y, width, height);

} 

AABB.prototype.reset = function (x, y, width, height) {

Rectangle.prototype.initialize.call(this, x, y, width, height);

this.setCencter();

this.setCorners();

this.setRange();

}

containPoint 检查点是否在包围盒内 参数是个Point对象

merge 返回一个能容纳两个包围盒的最小包围盒 参数是个AABB对象

reset 重置包围盒对象