Introduction - If you have any usage issues, please Google them yourself
Grid [tessellation] that is concave polygon contains holes, the island of multilateral type, or from cross-multilateral-type convex polygon is divided into easy process. OpenGL for fast rendering polygon, can only directly show that a simple convex polygon [arbitrary polygon two points to connect all the points still to this polygon], the multilateral or concave polygon rendering results from the cross will be uncertain. In rendering complex polygons, it is often required complex polygon into simple polygon rendering easier, OpenGL use library provides a function of grid through multilateral type contour line generates simple polygon, thereby rendering the complexity of the polygon.