2018-04-03 19:14:16 +00:00
|
|
|
|
// Copyright 2014 Google Inc. All rights reserved.
|
|
|
|
|
|
//
|
|
|
|
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
|
|
|
|
// you may not use this file except in compliance with the License.
|
|
|
|
|
|
// You may obtain a copy of the License at
|
|
|
|
|
|
//
|
|
|
|
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
|
|
//
|
|
|
|
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
|
|
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
|
|
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
|
|
|
|
// See the License for the specific language governing permissions and
|
|
|
|
|
|
// limitations under the License.
|
2017-06-27 20:50:36 +00:00
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
|
Package s2 implements types and functions for working with geometry in S² (spherical geometry).
|
|
|
|
|
|
|
|
|
|
|
|
Its related packages, parallel to this one, are s1 (operates on S¹), r1 (operates on ℝ¹)
|
|
|
|
|
|
and r3 (operates on ℝ³).
|
|
|
|
|
|
|
|
|
|
|
|
This package provides types and functions for the S2 cell hierarchy and coordinate systems.
|
|
|
|
|
|
The S2 cell hierarchy is a hierarchical decomposition of the surface of a unit sphere (S²)
|
|
|
|
|
|
into ``cells''; it is highly efficient, scales from continental size to under 1 cm²
|
|
|
|
|
|
and preserves spatial locality (nearby cells have close IDs).
|
|
|
|
|
|
|
|
|
|
|
|
A presentation that gives an overview of S2 is
|
|
|
|
|
|
https://docs.google.com/presentation/d/1Hl4KapfAENAOf4gv-pSngKwvS_jwNVHRPZTTDzXXn6Q/view.
|
|
|
|
|
|
*/
|
|
|
|
|
|
package s2
|
