gotosocial/vendor/github.com/golang/geo/s2/max_distance_targets.go
Tobi Smethurst 98263a7de6
Grand test fixup (#138)
* 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
2021-08-12 21:03:24 +02:00

306 lines
12 KiB
Go

// Copyright 2019 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 (
"math"
"github.com/golang/geo/s1"
)
// maxDistance implements distance as the supplementary distance (Pi - x) to find
// results that are the furthest using the distance related algorithms.
type maxDistance s1.ChordAngle
func (m maxDistance) chordAngle() s1.ChordAngle { return s1.ChordAngle(m) }
func (m maxDistance) zero() distance { return maxDistance(s1.StraightChordAngle) }
func (m maxDistance) negative() distance { return maxDistance(s1.InfChordAngle()) }
func (m maxDistance) infinity() distance { return maxDistance(s1.NegativeChordAngle) }
func (m maxDistance) less(other distance) bool { return m.chordAngle() > other.chordAngle() }
func (m maxDistance) sub(other distance) distance {
return maxDistance(m.chordAngle() + other.chordAngle())
}
func (m maxDistance) chordAngleBound() s1.ChordAngle {
return s1.StraightChordAngle - m.chordAngle()
}
func (m maxDistance) updateDistance(dist distance) (distance, bool) {
if dist.less(m) {
m = maxDistance(dist.chordAngle())
return m, true
}
return m, false
}
func (m maxDistance) fromChordAngle(o s1.ChordAngle) distance {
return maxDistance(o)
}
// MaxDistanceToPointTarget is used for computing the maximum distance to a Point.
type MaxDistanceToPointTarget struct {
point Point
dist distance
}
// NewMaxDistanceToPointTarget returns a new target for the given Point.
func NewMaxDistanceToPointTarget(point Point) *MaxDistanceToPointTarget {
m := maxDistance(0)
return &MaxDistanceToPointTarget{point: point, dist: &m}
}
func (m *MaxDistanceToPointTarget) capBound() Cap {
return CapFromCenterChordAngle(Point{m.point.Mul(-1)}, (s1.ChordAngle(0)))
}
func (m *MaxDistanceToPointTarget) updateDistanceToPoint(p Point, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(ChordAngleBetweenPoints(p, m.point)))
}
func (m *MaxDistanceToPointTarget) updateDistanceToEdge(edge Edge, dist distance) (distance, bool) {
if d, ok := UpdateMaxDistance(m.point, edge.V0, edge.V1, dist.chordAngle()); ok {
dist, _ = dist.updateDistance(maxDistance(d))
return dist, true
}
return dist, false
}
func (m *MaxDistanceToPointTarget) updateDistanceToCell(cell Cell, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(cell.MaxDistance(m.point)))
}
func (m *MaxDistanceToPointTarget) visitContainingShapes(index *ShapeIndex, v shapePointVisitorFunc) bool {
// For furthest points, we visit the polygons whose interior contains
// the antipode of the target point. These are the polygons whose
// distance to the target is maxDistance.zero()
q := NewContainsPointQuery(index, VertexModelSemiOpen)
return q.visitContainingShapes(Point{m.point.Mul(-1)}, func(shape Shape) bool {
return v(shape, m.point)
})
}
func (m *MaxDistanceToPointTarget) setMaxError(maxErr s1.ChordAngle) bool { return false }
func (m *MaxDistanceToPointTarget) maxBruteForceIndexSize() int { return 30 }
func (m *MaxDistanceToPointTarget) distance() distance { return m.dist }
// MaxDistanceToEdgeTarget is used for computing the maximum distance to an Edge.
type MaxDistanceToEdgeTarget struct {
e Edge
dist distance
}
// NewMaxDistanceToEdgeTarget returns a new target for the given Edge.
func NewMaxDistanceToEdgeTarget(e Edge) *MaxDistanceToEdgeTarget {
m := maxDistance(0)
return &MaxDistanceToEdgeTarget{e: e, dist: m}
}
// capBound returns a Cap that bounds the antipode of the target. (This
// is the set of points whose maxDistance to the target is maxDistance.zero)
func (m *MaxDistanceToEdgeTarget) capBound() Cap {
// The following computes a radius equal to half the edge length in an
// efficient and numerically stable way.
d2 := float64(ChordAngleBetweenPoints(m.e.V0, m.e.V1))
r2 := (0.5 * d2) / (1 + math.Sqrt(1-0.25*d2))
return CapFromCenterChordAngle(Point{m.e.V0.Add(m.e.V1.Vector).Mul(-1).Normalize()}, s1.ChordAngleFromSquaredLength(r2))
}
func (m *MaxDistanceToEdgeTarget) updateDistanceToPoint(p Point, dist distance) (distance, bool) {
if d, ok := UpdateMaxDistance(p, m.e.V0, m.e.V1, dist.chordAngle()); ok {
dist, _ = dist.updateDistance(maxDistance(d))
return dist, true
}
return dist, false
}
func (m *MaxDistanceToEdgeTarget) updateDistanceToEdge(edge Edge, dist distance) (distance, bool) {
if d, ok := updateEdgePairMaxDistance(m.e.V0, m.e.V1, edge.V0, edge.V1, dist.chordAngle()); ok {
dist, _ = dist.updateDistance(maxDistance(d))
return dist, true
}
return dist, false
}
func (m *MaxDistanceToEdgeTarget) updateDistanceToCell(cell Cell, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(cell.MaxDistanceToEdge(m.e.V0, m.e.V1)))
}
func (m *MaxDistanceToEdgeTarget) visitContainingShapes(index *ShapeIndex, v shapePointVisitorFunc) bool {
// We only need to test one edge point. That is because the method *must*
// visit a polygon if it fully contains the target, and *is allowed* to
// visit a polygon if it intersects the target. If the tested vertex is not
// contained, we know the full edge is not contained; if the tested vertex is
// contained, then the edge either is fully contained (must be visited) or it
// intersects (is allowed to be visited). We visit the center of the edge so
// that edge AB gives identical results to BA.
target := NewMaxDistanceToPointTarget(Point{m.e.V0.Add(m.e.V1.Vector).Normalize()})
return target.visitContainingShapes(index, v)
}
func (m *MaxDistanceToEdgeTarget) setMaxError(maxErr s1.ChordAngle) bool { return false }
func (m *MaxDistanceToEdgeTarget) maxBruteForceIndexSize() int { return 30 }
func (m *MaxDistanceToEdgeTarget) distance() distance { return m.dist }
// MaxDistanceToCellTarget is used for computing the maximum distance to a Cell.
type MaxDistanceToCellTarget struct {
cell Cell
dist distance
}
// NewMaxDistanceToCellTarget returns a new target for the given Cell.
func NewMaxDistanceToCellTarget(cell Cell) *MaxDistanceToCellTarget {
m := maxDistance(0)
return &MaxDistanceToCellTarget{cell: cell, dist: m}
}
func (m *MaxDistanceToCellTarget) capBound() Cap {
c := m.cell.CapBound()
return CapFromCenterAngle(Point{c.Center().Mul(-1)}, c.Radius())
}
func (m *MaxDistanceToCellTarget) updateDistanceToPoint(p Point, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(m.cell.MaxDistance(p)))
}
func (m *MaxDistanceToCellTarget) updateDistanceToEdge(edge Edge, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(m.cell.MaxDistanceToEdge(edge.V0, edge.V1)))
}
func (m *MaxDistanceToCellTarget) updateDistanceToCell(cell Cell, dist distance) (distance, bool) {
return dist.updateDistance(maxDistance(m.cell.MaxDistanceToCell(cell)))
}
func (m *MaxDistanceToCellTarget) visitContainingShapes(index *ShapeIndex, v shapePointVisitorFunc) bool {
// We only need to check one point here - cell center is simplest.
// See comment at MaxDistanceToEdgeTarget's visitContainingShapes.
target := NewMaxDistanceToPointTarget(m.cell.Center())
return target.visitContainingShapes(index, v)
}
func (m *MaxDistanceToCellTarget) setMaxError(maxErr s1.ChordAngle) bool { return false }
func (m *MaxDistanceToCellTarget) maxBruteForceIndexSize() int { return 30 }
func (m *MaxDistanceToCellTarget) distance() distance { return m.dist }
// MaxDistanceToShapeIndexTarget is used for computing the maximum distance to a ShapeIndex.
type MaxDistanceToShapeIndexTarget struct {
index *ShapeIndex
query *EdgeQuery
dist distance
}
// NewMaxDistanceToShapeIndexTarget returns a new target for the given ShapeIndex.
func NewMaxDistanceToShapeIndexTarget(index *ShapeIndex) *MaxDistanceToShapeIndexTarget {
m := maxDistance(0)
return &MaxDistanceToShapeIndexTarget{
index: index,
dist: m,
query: NewFurthestEdgeQuery(index, NewFurthestEdgeQueryOptions()),
}
}
// capBound returns a Cap that bounds the antipode of the target. This
// is the set of points whose maxDistance to the target is maxDistance.zero()
func (m *MaxDistanceToShapeIndexTarget) capBound() Cap {
// TODO(roberts): Depends on ShapeIndexRegion
// c := makeShapeIndexRegion(m.index).CapBound()
// return CapFromCenterRadius(Point{c.Center.Mul(-1)}, c.Radius())
panic("not implemented yet")
}
func (m *MaxDistanceToShapeIndexTarget) updateDistanceToPoint(p Point, dist distance) (distance, bool) {
m.query.opts.distanceLimit = dist.chordAngle()
target := NewMaxDistanceToPointTarget(p)
r := m.query.findEdge(target, m.query.opts)
if r.shapeID < 0 {
return dist, false
}
return r.distance, true
}
func (m *MaxDistanceToShapeIndexTarget) updateDistanceToEdge(edge Edge, dist distance) (distance, bool) {
m.query.opts.distanceLimit = dist.chordAngle()
target := NewMaxDistanceToEdgeTarget(edge)
r := m.query.findEdge(target, m.query.opts)
if r.shapeID < 0 {
return dist, false
}
return r.distance, true
}
func (m *MaxDistanceToShapeIndexTarget) updateDistanceToCell(cell Cell, dist distance) (distance, bool) {
m.query.opts.distanceLimit = dist.chordAngle()
target := NewMaxDistanceToCellTarget(cell)
r := m.query.findEdge(target, m.query.opts)
if r.shapeID < 0 {
return dist, false
}
return r.distance, true
}
// visitContainingShapes returns the polygons containing the antipodal
// reflection of *any* connected component for target types consisting of
// multiple connected components. It is sufficient to test containment of
// one vertex per connected component, since this allows us to also return
// any polygon whose boundary has distance.zero() to the target.
func (m *MaxDistanceToShapeIndexTarget) visitContainingShapes(index *ShapeIndex, v shapePointVisitorFunc) bool {
// It is sufficient to find the set of chain starts in the target index
// (i.e., one vertex per connected component of edges) that are contained by
// the query index, except for one special case to handle full polygons.
//
// TODO(roberts): Do this by merge-joining the two ShapeIndexes and share
// the code with BooleanOperation.
for _, shape := range m.index.shapes {
numChains := shape.NumChains()
// Shapes that don't have any edges require a special case (below).
testedPoint := false
for c := 0; c < numChains; c++ {
chain := shape.Chain(c)
if chain.Length == 0 {
continue
}
testedPoint = true
target := NewMaxDistanceToPointTarget(shape.ChainEdge(c, 0).V0)
if !target.visitContainingShapes(index, v) {
return false
}
}
if !testedPoint {
// Special case to handle full polygons.
ref := shape.ReferencePoint()
if !ref.Contained {
continue
}
target := NewMaxDistanceToPointTarget(ref.Point)
if !target.visitContainingShapes(index, v) {
return false
}
}
}
return true
}
func (m *MaxDistanceToShapeIndexTarget) setMaxError(maxErr s1.ChordAngle) bool {
m.query.opts.maxError = maxErr
return true
}
func (m *MaxDistanceToShapeIndexTarget) maxBruteForceIndexSize() int { return 30 }
func (m *MaxDistanceToShapeIndexTarget) distance() distance { return m.dist }
func (m *MaxDistanceToShapeIndexTarget) setIncludeInteriors(b bool) {
m.query.opts.includeInteriors = b
}
func (m *MaxDistanceToShapeIndexTarget) setUseBruteForce(b bool) { m.query.opts.useBruteForce = b }
// TODO(roberts): Remaining methods
//
// func (m *MaxDistanceToShapeIndexTarget) capBound() Cap {
// CellUnionTarget