mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2025-10-31 05:12:25 -05:00
98263a7de6* start fixing up tests * fix up tests + automate with drone * fiddle with linting * messing about with drone.yml * some more fiddling * hmmm * add cache * add vendor directory * verbose * ci updates * update some little things * update sig
101 lines
3.4 KiB
Go
101 lines
3.4 KiB
Go
// 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.
|
|
|
|
package s2
|
|
|
|
import (
|
|
"fmt"
|
|
"math"
|
|
|
|
"github.com/golang/geo/r3"
|
|
"github.com/golang/geo/s1"
|
|
)
|
|
|
|
const (
|
|
northPoleLat = s1.Angle(math.Pi/2) * s1.Radian
|
|
southPoleLat = -northPoleLat
|
|
)
|
|
|
|
// LatLng represents a point on the unit sphere as a pair of angles.
|
|
type LatLng struct {
|
|
Lat, Lng s1.Angle
|
|
}
|
|
|
|
// LatLngFromDegrees returns a LatLng for the coordinates given in degrees.
|
|
func LatLngFromDegrees(lat, lng float64) LatLng {
|
|
return LatLng{s1.Angle(lat) * s1.Degree, s1.Angle(lng) * s1.Degree}
|
|
}
|
|
|
|
// IsValid returns true iff the LatLng is normalized, with Lat ∈ [-π/2,π/2] and Lng ∈ [-π,π].
|
|
func (ll LatLng) IsValid() bool {
|
|
return math.Abs(ll.Lat.Radians()) <= math.Pi/2 && math.Abs(ll.Lng.Radians()) <= math.Pi
|
|
}
|
|
|
|
// Normalized returns the normalized version of the LatLng,
|
|
// with Lat clamped to [-π/2,π/2] and Lng wrapped in [-π,π].
|
|
func (ll LatLng) Normalized() LatLng {
|
|
lat := ll.Lat
|
|
if lat > northPoleLat {
|
|
lat = northPoleLat
|
|
} else if lat < southPoleLat {
|
|
lat = southPoleLat
|
|
}
|
|
lng := s1.Angle(math.Remainder(ll.Lng.Radians(), 2*math.Pi)) * s1.Radian
|
|
return LatLng{lat, lng}
|
|
}
|
|
|
|
func (ll LatLng) String() string { return fmt.Sprintf("[%v, %v]", ll.Lat, ll.Lng) }
|
|
|
|
// Distance returns the angle between two LatLngs.
|
|
func (ll LatLng) Distance(ll2 LatLng) s1.Angle {
|
|
// Haversine formula, as used in C++ S2LatLng::GetDistance.
|
|
lat1, lat2 := ll.Lat.Radians(), ll2.Lat.Radians()
|
|
lng1, lng2 := ll.Lng.Radians(), ll2.Lng.Radians()
|
|
dlat := math.Sin(0.5 * (lat2 - lat1))
|
|
dlng := math.Sin(0.5 * (lng2 - lng1))
|
|
x := dlat*dlat + dlng*dlng*math.Cos(lat1)*math.Cos(lat2)
|
|
return s1.Angle(2*math.Atan2(math.Sqrt(x), math.Sqrt(math.Max(0, 1-x)))) * s1.Radian
|
|
}
|
|
|
|
// NOTE(mikeperrow): The C++ implementation publicly exposes latitude/longitude
|
|
// functions. Let's see if that's really necessary before exposing the same functionality.
|
|
|
|
func latitude(p Point) s1.Angle {
|
|
return s1.Angle(math.Atan2(p.Z, math.Sqrt(p.X*p.X+p.Y*p.Y))) * s1.Radian
|
|
}
|
|
|
|
func longitude(p Point) s1.Angle {
|
|
return s1.Angle(math.Atan2(p.Y, p.X)) * s1.Radian
|
|
}
|
|
|
|
// PointFromLatLng returns an Point for the given LatLng.
|
|
// The maximum error in the result is 1.5 * dblEpsilon. (This does not
|
|
// include the error of converting degrees, E5, E6, or E7 into radians.)
|
|
func PointFromLatLng(ll LatLng) Point {
|
|
phi := ll.Lat.Radians()
|
|
theta := ll.Lng.Radians()
|
|
cosphi := math.Cos(phi)
|
|
return Point{r3.Vector{math.Cos(theta) * cosphi, math.Sin(theta) * cosphi, math.Sin(phi)}}
|
|
}
|
|
|
|
// LatLngFromPoint returns an LatLng for a given Point.
|
|
func LatLngFromPoint(p Point) LatLng {
|
|
return LatLng{latitude(p), longitude(p)}
|
|
}
|
|
|
|
// ApproxEqual reports whether the latitude and longitude of the two LatLngs
|
|
// are the same up to a small tolerance.
|
|
func (ll LatLng) ApproxEqual(other LatLng) bool {
|
|
return ll.Lat.ApproxEqual(other.Lat) && ll.Lng.ApproxEqual(other.Lng)
|
|
}
|