2016-03-05 02:08:16 +03:00
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package geojson
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import (
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"bytes"
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"strconv"
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"github.com/tidwall/tile38/geojson/geohash"
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)
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// Polygon is a geojson object with the type "Polygon"
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type Polygon struct {
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Coordinates [][]Position
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BBox *BBox
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}
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2016-12-17 00:02:58 +03:00
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func fillPolygon(coordinates [][]Position, bbox *BBox, err error) (Polygon, error) {
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2016-03-05 02:08:16 +03:00
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if err == nil {
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if len(coordinates) == 0 {
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err = errMustBeALinearRing
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}
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}
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if err == nil {
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for _, ps := range coordinates {
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if !isLinearRing(ps) {
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err = errMustBeALinearRing
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break
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}
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}
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}
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return Polygon{
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Coordinates: coordinates,
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BBox: bbox,
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2016-12-17 00:02:58 +03:00
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}, err
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2016-03-05 02:08:16 +03:00
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}
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// CalculatedBBox is exterior bbox containing the object.
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func (g Polygon) CalculatedBBox() BBox {
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return level3CalculatedBBox(g.Coordinates, g.BBox, true)
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}
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// CalculatedPoint is a point representation of the object.
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func (g Polygon) CalculatedPoint() Position {
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return g.CalculatedBBox().center()
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}
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// Geohash converts the object to a geohash value.
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func (g Polygon) Geohash(precision int) (string, error) {
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p := g.CalculatedPoint()
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return geohash.Encode(p.Y, p.X, precision)
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}
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// PositionCount return the number of coordinates.
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func (g Polygon) PositionCount() int {
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return level3PositionCount(g.Coordinates, g.BBox)
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}
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// Weight returns the in-memory size of the object.
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func (g Polygon) Weight() int {
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return level3Weight(g.Coordinates, g.BBox)
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}
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// MarshalJSON allows the object to be encoded in json.Marshal calls.
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func (g Polygon) MarshalJSON() ([]byte, error) {
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return []byte(g.JSON()), nil
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}
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// JSON is the json representation of the object. This might not be exactly the same as the original.
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func (g Polygon) JSON() string {
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return level3JSON("Polygon", g.Coordinates, g.BBox)
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}
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2016-07-10 05:44:28 +03:00
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// String returns a string representation of the object. This might be JSON or something else.
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func (g Polygon) String() string {
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return g.JSON()
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}
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2016-03-05 02:08:16 +03:00
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func (g Polygon) bboxPtr() *BBox {
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return g.BBox
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}
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func (g Polygon) hasPositions() bool {
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if g.BBox != nil {
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return true
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}
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for _, c := range g.Coordinates {
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if len(c) > 0 {
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return true
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}
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}
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return false
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}
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// WithinBBox detects if the object is fully contained inside a bbox.
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func (g Polygon) WithinBBox(bbox BBox) bool {
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if g.BBox != nil {
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return rectBBox(g.CalculatedBBox()).InsideRect(rectBBox(bbox))
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}
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if len(g.Coordinates) == 0 {
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return false
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}
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2017-12-18 18:37:03 +03:00
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rbbox := rectBBox(bbox)
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ext, holes := polyExteriorHoles(g.Coordinates)
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if len(holes) > 0 {
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if rbbox.Max == rbbox.Min {
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return rbbox.Min.Inside(ext, holes)
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}
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return rbbox.Inside(ext, holes)
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}
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return ext.InsideRect(rectBBox(bbox))
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2016-03-05 02:08:16 +03:00
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}
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// IntersectsBBox detects if the object intersects a bbox.
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func (g Polygon) IntersectsBBox(bbox BBox) bool {
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if g.BBox != nil {
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return rectBBox(g.CalculatedBBox()).IntersectsRect(rectBBox(bbox))
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}
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if len(g.Coordinates) == 0 {
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return false
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}
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2017-12-18 18:37:03 +03:00
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rbbox := rectBBox(bbox)
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ext, holes := polyExteriorHoles(g.Coordinates)
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if len(holes) > 0 {
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if rbbox.Max == rbbox.Min {
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return rbbox.Min.Intersects(ext, holes)
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}
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return rbbox.Intersects(ext, holes)
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}
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return ext.IntersectsRect(rectBBox(bbox))
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2016-03-05 02:08:16 +03:00
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}
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// Within detects if the object is fully contained inside another object.
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func (g Polygon) Within(o Object) bool {
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return withinObjectShared(g, o,
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func(v Polygon) bool {
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if len(g.Coordinates) == 0 {
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return false
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}
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return polyPositions(g.Coordinates[0]).Inside(polyExteriorHoles(v.Coordinates))
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},
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func(v MultiPolygon) bool {
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if len(g.Coordinates) == 0 {
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return false
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}
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for _, c := range v.Coordinates {
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if !polyPositions(g.Coordinates[0]).Inside(polyExteriorHoles(c)) {
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return false
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}
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}
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return true
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},
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)
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}
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// Intersects detects if the object intersects another object.
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func (g Polygon) Intersects(o Object) bool {
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return intersectsObjectShared(g, o,
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func(v Polygon) bool {
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if len(g.Coordinates) == 0 {
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return false
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}
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return polyPositions(g.Coordinates[0]).Intersects(polyExteriorHoles(v.Coordinates))
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},
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func(v MultiPolygon) bool {
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if len(g.Coordinates) == 0 {
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return false
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}
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for _, c := range v.Coordinates {
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if polyPositions(g.Coordinates[0]).Intersects(polyExteriorHoles(c)) {
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return true
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}
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}
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return false
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},
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)
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}
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// Nearby detects if the object is nearby a position.
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func (g Polygon) Nearby(center Position, meters float64) bool {
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return nearbyObjectShared(g, center.X, center.Y, meters)
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}
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// KML outputs kml
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func (g Polygon) KML() string {
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var buf bytes.Buffer
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buf.WriteString(`<?xml version="1.0" encoding="UTF-8"?>`)
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buf.WriteString(`<kml xmlns="http://www.opengis.net/kml/2.2">`)
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buf.WriteString(`<Placemark>`)
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buf.WriteString(`<Polygon>`)
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buf.WriteString(`<extrude>1</extrude>`)
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buf.WriteString(`<altitudeMode>relativeToGround</altitudeMode>`)
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for i, c := range g.Coordinates {
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if i == 0 {
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buf.WriteString(`<outerBoundaryIs>`)
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} else {
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buf.WriteString(`<innerBoundaryIs>`)
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}
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buf.WriteString(`<LinearRing>`)
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buf.WriteString(`<coordinates>`)
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for _, c := range c {
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buf.WriteString("\n" + strconv.FormatFloat(c.X, 'f', -1, 64) + `,` + strconv.FormatFloat(c.Y, 'f', -1, 64) + `,` + strconv.FormatFloat(c.Z, 'f', -1, 64))
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}
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if len(c) > 0 {
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buf.WriteString("\n")
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}
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buf.WriteString(`</coordinates>`)
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buf.WriteString(`</LinearRing>`)
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if i == 0 {
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buf.WriteString(`</outerBoundaryIs>`)
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} else {
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buf.WriteString(`</innerBoundaryIs>`)
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}
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}
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buf.WriteString(`</Polygon>`)
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buf.WriteString(`</Placemark>`)
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buf.WriteString(`</kml>`)
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return buf.String()
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}
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// IsBBoxDefined returns true if the object has a defined bbox.
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func (g Polygon) IsBBoxDefined() bool {
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return g.BBox != nil
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}
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2016-07-10 05:44:28 +03:00
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// IsGeometry return true if the object is a geojson geometry object. false if it something else.
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func (g Polygon) IsGeometry() bool {
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return true
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}
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