code: function(p, angle) {
              p = point(p);
  	    var center = point(this.x + this.width/2, this.y + this.height/2);
              var result;
              if (angle) p.rotate(center, angle);
              
  	    // (clockwise, starting from the top side)
  	    var sides = [
  	        line(this.origin(), this.topRight()),
  	        line(this.topRight(), this.corner()),
  	        line(this.corner(), this.bottomLeft()),
  	        line(this.bottomLeft(), this.origin())
  	    ];
  	    var connector = line(center, p);
              
  	    for (var i = sides.length - 1; i >= 0; --i){
  	        var intersection = sides[i].intersection(connector);
  	        if (intersection !== null){
  		    result = intersection;
                      break;
  	        }
  	    }
              if (result && angle) result.rotate(center, -angle);
              return result;
          }
docs: Find point on my boundary where line starting from my center ending in point p intersects me. @param {number} angle If angle is specified, intersection with rotated rectangle is computed.