Directions: Draw a polygon by clicking the canvas below to add vertecies in a clockwise order. If the vertecies are not in clockwise order or the polygon self-intersects then the algorithm doesn't know what is "inside" the polygon and will give a nonsense triangulation or an error. Click Triangulate to triangulate your polygon and clear to start over. To see some examples click Chvátal's Comb or Godfried's Favorite Polygon.
An implementation by Nicholas Wellcome - Source