1 files changed, 306 insertions, 0 deletions
diff --git a/vendor/github.com/golang/geo/s2/max_distance_targets.go b/vendor/github.com/golang/geo/s2/max_distance_targets.go
new file mode 100644
index 000000000..589231890
--- /dev/null
+++ b/vendor/github.com/golang/geo/s2/max_distance_targets.go
@@ -0,0 +1,306 @@
+// 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 300 }
+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 110 }
+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 100 }
+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 70 }
+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