//Makes a 3D coordinate
   //===================================================================
   function Point(x,y,z) {
    this.x = x;
    this.y = y;
    this.z = z;   //if omit z value, just make point 2D
    return this;
   }
   
   //Makes a 3D vector A(x,y,z) -> B(x,y,z)
   //===================================================================
   function Vector(a,b,c) {
    this.a = a;    //Point
    this.b = b;
    this.c = c;
    return this;
   }
   
  
   //The points are projected onto the plane defined by the viewport vector
   var viewport = new Vector(new Point(-100,-190,-100),new Point(100,10,-100), new Point(50,50));
  
   //The camera's position is used for calculating focal length and where
   //the points should be plotted on the viewport
   var camera = new Point(0,-90,-200);