fill_polygon_relative(+Drawable, +Points, +Shape)
     fill_polygon_relative(+Drawable, +Gc, +Points, +Shape)

Draw a filled polygon. Points is a list of point(X,Y) terms, each specifying the location of one vertex of the polygon relative to the previous point. Shape is either complex, meaning the polygon may contain intersecting edges, nonconvex, meaning no edges intersect, or convex, meaning that no edges intersect, and further, the polygon is wholly convex.