code: function(obj) {
                  if (this.intersects(obj) || this.contains(obj)) { return 0; }
                  if (obj.anchor) {
                    // obj is a plane or line
                    var A = this.anchor.elements, B = obj.anchor.elements, N = this.normal.elements;
                    return Math.abs((A[0] - B[0]) * N[0] + (A[1] - B[1]) * N[1] + (A[2] - B[2]) * N[2]);
                  } else {
                    // obj is a point
                    var P = obj.elements || obj;
                    var A = this.anchor.elements, N = this.normal.elements;
                    return Math.abs((A[0] - P[0]) * N[0] + (A[1] - P[1]) * N[1] + (A[2] - (P[2] || 0)) * N[2]);
                  }
                }
docs: Returns the plane's distance from the given object (point, line or plane)