110 lines
3.3 KiB
Go
110 lines
3.3 KiB
Go
// Copyright (c) 2019 Couchbase, Inc.
|
|
//
|
|
// 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 searcher
|
|
|
|
import (
|
|
"github.com/blevesearch/bleve/geo"
|
|
"github.com/blevesearch/bleve/index"
|
|
"github.com/blevesearch/bleve/numeric"
|
|
"github.com/blevesearch/bleve/search"
|
|
"math"
|
|
)
|
|
|
|
func NewGeoBoundedPolygonSearcher(indexReader index.IndexReader,
|
|
polygon []geo.Point, field string, boost float64,
|
|
options search.SearcherOptions) (search.Searcher, error) {
|
|
|
|
// compute the bounding box enclosing the polygon
|
|
topLeftLon, topLeftLat, bottomRightLon, bottomRightLat, err :=
|
|
geo.BoundingRectangleForPolygon(polygon)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// build a searcher for the bounding box on the polygon
|
|
boxSearcher, err := boxSearcher(indexReader,
|
|
topLeftLon, topLeftLat, bottomRightLon, bottomRightLat,
|
|
field, boost, options, true)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
dvReader, err := indexReader.DocValueReader([]string{field})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// wrap it in a filtering searcher that checks for the polygon inclusivity
|
|
return NewFilteringSearcher(boxSearcher,
|
|
buildPolygonFilter(dvReader, field, polygon)), nil
|
|
}
|
|
|
|
const float64EqualityThreshold = 1e-6
|
|
|
|
func almostEqual(a, b float64) bool {
|
|
return math.Abs(a-b) <= float64EqualityThreshold
|
|
}
|
|
|
|
// buildPolygonFilter returns true if the point lies inside the
|
|
// polygon. It is based on the ray-casting technique as referred
|
|
// here: https://wrf.ecse.rpi.edu/nikola/pubdetails/pnpoly.html
|
|
func buildPolygonFilter(dvReader index.DocValueReader, field string,
|
|
polygon []geo.Point) FilterFunc {
|
|
return func(d *search.DocumentMatch) bool {
|
|
var lon, lat float64
|
|
var found bool
|
|
|
|
err := dvReader.VisitDocValues(d.IndexInternalID, func(field string, term []byte) {
|
|
// only consider the values which are shifted 0
|
|
prefixCoded := numeric.PrefixCoded(term)
|
|
shift, err := prefixCoded.Shift()
|
|
if err == nil && shift == 0 {
|
|
i64, err := prefixCoded.Int64()
|
|
if err == nil {
|
|
lon = geo.MortonUnhashLon(uint64(i64))
|
|
lat = geo.MortonUnhashLat(uint64(i64))
|
|
found = true
|
|
}
|
|
}
|
|
})
|
|
|
|
// Note: this approach works for points which are strictly inside
|
|
// the polygon. ie it might fail for certain points on the polygon boundaries.
|
|
if err == nil && found {
|
|
nVertices := len(polygon)
|
|
var inside bool
|
|
// check for a direct vertex match
|
|
if almostEqual(polygon[0].Lat, lat) &&
|
|
almostEqual(polygon[0].Lon, lon) {
|
|
return true
|
|
}
|
|
|
|
for i := 1; i < nVertices; i++ {
|
|
if almostEqual(polygon[i].Lat, lat) &&
|
|
almostEqual(polygon[i].Lon, lon) {
|
|
return true
|
|
}
|
|
if (polygon[i].Lat > lat) != (polygon[i-1].Lat > lat) &&
|
|
lon < (polygon[i-1].Lon-polygon[i].Lon)*(lat-polygon[i].Lat)/
|
|
(polygon[i-1].Lat-polygon[i].Lat)+polygon[i].Lon {
|
|
inside = !inside
|
|
}
|
|
}
|
|
return inside
|
|
|
|
}
|
|
return false
|
|
}
|
|
}
|