function Spiral() {
    Geometry.apply(this, arguments);
    this.point = null;
	this.point1=null;
	this.point2=null;
	this.points = [];
	this.sAngle=0;
	this.eAngle=1.5*Math.PI;
	this.selectIndex=null;
	this.symbolType="Stair";
};

Spiral.prototype = new Geometry();
Spiral.prototype.geoType = "Spiral";