EDIT with more info from comments
It sounds like what you really want is the convex hull of your points since your points, ordered like they are now, do not create a rectangle.
dt = delaunayTriangulation(xr,yr);
hullidx = convexHull(dt);
xa = xr(hullidx);
ya = yr(hullidx);
[xa,ya] = poly2cw(xa,ya);
comet(xa,ya)
If you don't want the convex hull but do want to encourage your shape to be close to convex, then look at alphaShape which will also do a triangulation for you but will allow concavities below a certain size based on alpha.
Original
It starts in the upper left hand corner at (0,1) and moves to (1,1) and then down to (1,0) before completing the triangle. This is indeed clockwise
comet(xr,yr)
