package{
	//point3D class
	//
	//Constructor sets up a 3D point in x,y,z and performs perspective 
	//projection into two-D using the vp(vanishing point) and fl(focal length)
	//

	import flash.geom.Point;
	public class point3D{
		public var twoD:Point; //holds the two-D projection of the point
		public var x:Number, y:Number, z:Number; //3D location of point
		private var xcp:Number, ycp:Number, zcp:Number; //x,y,z copies 
		private var vp:Point, fl:Number; //vanishing point and focal length
		public function point3D(x:int, y:int, z:int, vp:Point, fl:Number) {
			xcp=this.x=x; ycp=this.y=y; zcp=this.z=z;
			this.vp=vp; this.fl=fl;
			calcPerspective();	
		}
		private function calcPerspective():void{
			//do perspective projection
			var scale:Number = fl/(fl+z);
			var x2:Number=vp.x+x*scale;
			var y2:Number=vp.y+y*scale;
			twoD=new Point(x2, y2);				
		}
		public function resetTransformation():void{
			//restore point3D to original position:
			x=xcp; y=ycp; z=zcp;
			calcPerspective();		
		}
		public function translate(tx:Number, ty:Number, tz:Number):void{
			x+=tx; y+=ty; z+=tz;
			calcPerspective();
		}
		public function rotateAboutY(angle:Number):void{
			var cos:Number=Math.cos(-angle*Math.PI/180);
			var sin:Number=Math.sin(-angle*Math.PI/180);
			x=x*cos-z*sin;
			z=x*sin+z*cos;
			calcPerspective();		
		}
	}
}