Method IsNormalized

s2/loop.go:860–872

IsNormalized reports whether the loop area is at most 2*pi. Degenerate loops are handled consistently with Sign, i.e., if a loop can be expressed as the union of degenerate or nearly-degenerate CCW triangles, then it will always be considered normalized.

()

// expressed as the union of degenerate or nearly-degenerate CCW triangles,
// then it will always be considered normalized.
func (l *Loop) IsNormalized() bool {
	// Optimization: if the longitude span is less than 180 degrees, then the
	// loop covers less than half the sphere and is therefore normalized.
	if l.bound.Lng.Length() < math.Pi {
		return true
	}

	// We allow some error so that hemispheres are always considered normalized.
	// TODO(roberts): This is no longer required by the Polygon implementation,
	// so alternatively we could create the invariant that a loop is normalized
	// if and only if its complement is not normalized.
	return l.TurningAngle() >= -l.turningAngleMaxError()
}

// Normalize inverts the loop if necessary so that the area enclosed by the loop
// is at most 2*pi.