Struct Loop

s2/loop.go:45–69

Loop represents a simple spherical polygon. It consists of a sequence of vertices where the first vertex is implicitly connected to the last. All loops are defined to have a CCW orientation, i.e. the interior of the loop is on the left side of the edges. This implies that a clockwise loop enclosing

// chain, they are defined as having exactly one vertex each (see EmptyLoop
// and FullLoop).
type Loop struct {
	vertices []Point

	// originInside keeps a precomputed value whether this loop contains the origin
	// versus computing from the set of vertices every time.
	originInside bool

	// depth is the nesting depth of this Loop if it is contained by a Polygon
	// or other shape and is used to determine if this loop represents a hole
	// or a filled in portion.
	depth int

	// bound is a conservative bound on all points contained by this loop.
	// If l.ContainsPoint(P), then l.bound.ContainsPoint(P).
	bound Rect

	// Since bound is not exact, it is possible that a loop A contains
	// another loop B whose bounds are slightly larger. subregionBound
	// has been expanded sufficiently to account for this error, i.e.
	// if A.Contains(B), then A.subregionBound.Contains(B.bound).
	subregionBound Rect

	// index is the spatial index for this Loop.
	index *ShapeIndex
}

// LoopFromPoints constructs a loop from the given points.
func LoopFromPoints(pts []Point) *Loop {