# Matlab POLYBOOL contours

Matlab polybool has external and internal contours.

- External contour
- the vertices describing the outer edge of a polygon–the outside of a donut, for example. These vertices must be given in CLOCKWISE order.
- Internal contour
- the vertices describing an area in which the convex hull is hollow (the donut hole). These vertices must be given in COUNTERclockwise order.