Function PolygonFromLoops

s2/polygon.go:92–102

PolygonFromLoops constructs a polygon from the given set of loops. The polygon interior consists of the points contained by an odd number of loops. (Recall that a loop contains the set of points on its left-hand side.) This method determines the loop nesting hierarchy and assigns every loop a depth

(loops []*Loop)

// Note: The given set of loops are reordered by this method so that the hierarchy
// can be traversed using Parent, LastDescendant and the loops depths.
func PolygonFromLoops(loops []*Loop) *Polygon {
	p := &Polygon{}
	// Empty polygons do not contain any loops, even the Empty loop.
	if len(loops) == 1 && loops[0].IsEmpty() {
		p.initLoopProperties()
		return p
	}
	p.loops = loops
	p.initNested()
	return p
}

// PolygonFromOrientedLoops returns a Polygon from the given set of loops,
// like PolygonFromLoops. It expects loops to be oriented such that the polygon