GoToSocial/vendor/github.com/golang/geo/s2/contains_point_query.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

191 lines
6.2 KiB
Go

// Copyright 2018 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
// VertexModel defines whether shapes are considered to contain their vertices.
// Note that these definitions differ from the ones used by BooleanOperation.
//
// Note that points other than vertices are never contained by polylines.
// If you want need this behavior, use ClosestEdgeQuery's IsDistanceLess
// with a suitable distance threshold instead.
type VertexModel int
const (
// VertexModelOpen means no shapes contain their vertices (not even
// points). Therefore Contains(Point) returns true if and only if the
// point is in the interior of some polygon.
VertexModelOpen VertexModel = iota
// VertexModelSemiOpen means that polygon point containment is defined
// such that if several polygons tile the region around a vertex, then
// exactly one of those polygons contains that vertex. Points and
// polylines still do not contain any vertices.
VertexModelSemiOpen
// VertexModelClosed means all shapes contain their vertices (including
// points and polylines).
VertexModelClosed
)
// ContainsPointQuery determines whether one or more shapes in a ShapeIndex
// contain a given Point. The ShapeIndex may contain any number of points,
// polylines, and/or polygons (possibly overlapping). Shape boundaries may be
// modeled as Open, SemiOpen, or Closed (this affects whether or not shapes are
// considered to contain their vertices).
//
// This type is not safe for concurrent use.
//
// However, note that if you need to do a large number of point containment
// tests, it is more efficient to re-use the query rather than creating a new
// one each time.
type ContainsPointQuery struct {
model VertexModel
index *ShapeIndex
iter *ShapeIndexIterator
}
// NewContainsPointQuery creates a new instance of the ContainsPointQuery for the index
// and given vertex model choice.
func NewContainsPointQuery(index *ShapeIndex, model VertexModel) *ContainsPointQuery {
return &ContainsPointQuery{
index: index,
model: model,
iter: index.Iterator(),
}
}
// Contains reports whether any shape in the queries index contains the point p
// under the queries vertex model (Open, SemiOpen, or Closed).
func (q *ContainsPointQuery) Contains(p Point) bool {
if !q.iter.LocatePoint(p) {
return false
}
cell := q.iter.IndexCell()
for _, clipped := range cell.shapes {
if q.shapeContains(clipped, q.iter.Center(), p) {
return true
}
}
return false
}
// shapeContains reports whether the clippedShape from the iterator's center position contains
// the given point.
func (q *ContainsPointQuery) shapeContains(clipped *clippedShape, center, p Point) bool {
inside := clipped.containsCenter
numEdges := clipped.numEdges()
if numEdges <= 0 {
return inside
}
shape := q.index.Shape(clipped.shapeID)
if shape.Dimension() != 2 {
// Points and polylines can be ignored unless the vertex model is Closed.
if q.model != VertexModelClosed {
return false
}
// Otherwise, the point is contained if and only if it matches a vertex.
for _, edgeID := range clipped.edges {
edge := shape.Edge(edgeID)
if edge.V0 == p || edge.V1 == p {
return true
}
}
return false
}
// Test containment by drawing a line segment from the cell center to the
// given point and counting edge crossings.
crosser := NewEdgeCrosser(center, p)
for _, edgeID := range clipped.edges {
edge := shape.Edge(edgeID)
sign := crosser.CrossingSign(edge.V0, edge.V1)
if sign == DoNotCross {
continue
}
if sign == MaybeCross {
// For the Open and Closed models, check whether p is a vertex.
if q.model != VertexModelSemiOpen && (edge.V0 == p || edge.V1 == p) {
return (q.model == VertexModelClosed)
}
// C++ plays fast and loose with the int <-> bool conversions here.
if VertexCrossing(crosser.a, crosser.b, edge.V0, edge.V1) {
sign = Cross
} else {
sign = DoNotCross
}
}
inside = inside != (sign == Cross)
}
return inside
}
// ShapeContains reports whether the given shape contains the point under this
// queries vertex model (Open, SemiOpen, or Closed).
//
// This requires the shape belongs to this queries index.
func (q *ContainsPointQuery) ShapeContains(shape Shape, p Point) bool {
if !q.iter.LocatePoint(p) {
return false
}
clipped := q.iter.IndexCell().findByShapeID(q.index.idForShape(shape))
if clipped == nil {
return false
}
return q.shapeContains(clipped, q.iter.Center(), p)
}
// shapeVisitorFunc is a type of function that can be called against shaped in an index.
type shapeVisitorFunc func(shape Shape) bool
// visitContainingShapes visits all shapes in the given index that contain the
// given point p, terminating early if the given visitor function returns false,
// in which case visitContainingShapes returns false. Each shape is
// visited at most once.
func (q *ContainsPointQuery) visitContainingShapes(p Point, f shapeVisitorFunc) bool {
// This function returns false only if the algorithm terminates early
// because the visitor function returned false.
if !q.iter.LocatePoint(p) {
return true
}
cell := q.iter.IndexCell()
for _, clipped := range cell.shapes {
if q.shapeContains(clipped, q.iter.Center(), p) &&
!f(q.index.Shape(clipped.shapeID)) {
return false
}
}
return true
}
// ContainingShapes returns a slice of all shapes that contain the given point.
func (q *ContainsPointQuery) ContainingShapes(p Point) []Shape {
var shapes []Shape
q.visitContainingShapes(p, func(shape Shape) bool {
shapes = append(shapes, shape)
return true
})
return shapes
}
// TODO(roberts): Remaining methods from C++
// type edgeVisitorFunc func(shape ShapeEdge) bool
// func (q *ContainsPointQuery) visitIncidentEdges(p Point, v edgeVisitorFunc) bool