tile38/pkg/geojson/polygon.go

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package geojson
import "github.com/tidwall/tile38/pkg/geojson/geohash"
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// Polygon is a geojson object with the type "Polygon"
type Polygon struct {
Coordinates [][]Position
BBox *BBox
bboxDefined bool
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}
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func fillPolygon(coordinates [][]Position, bbox *BBox, err error) (Polygon, error) {
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if err == nil {
if len(coordinates) == 0 {
err = errMustBeALinearRing
}
}
if err == nil {
for _, ps := range coordinates {
if !isLinearRing(ps) {
err = errMustBeALinearRing
break
}
}
}
bboxDefined := bbox != nil
if !bboxDefined {
cbbox := level3CalculatedBBox(coordinates, nil, true)
bbox = &cbbox
}
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return Polygon{
Coordinates: coordinates,
BBox: bbox,
bboxDefined: bboxDefined,
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}, err
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}
// CalculatedBBox is exterior bbox containing the object.
func (g Polygon) CalculatedBBox() BBox {
return level3CalculatedBBox(g.Coordinates, g.BBox, true)
}
// CalculatedPoint is a point representation of the object.
func (g Polygon) CalculatedPoint() Position {
return g.CalculatedBBox().center()
}
// Geohash converts the object to a geohash value.
func (g Polygon) Geohash(precision int) (string, error) {
p := g.CalculatedPoint()
return geohash.Encode(p.Y, p.X, precision)
}
// PositionCount return the number of coordinates.
func (g Polygon) PositionCount() int {
return level3PositionCount(g.Coordinates, g.BBox)
}
// Weight returns the in-memory size of the object.
func (g Polygon) Weight() int {
return level3Weight(g.Coordinates, g.BBox)
}
// MarshalJSON allows the object to be encoded in json.Marshal calls.
func (g Polygon) MarshalJSON() ([]byte, error) {
return g.appendJSON(nil), nil
}
func (g Polygon) appendJSON(json []byte) []byte {
return appendLevel3JSON(json, "Polygon", g.Coordinates, g.BBox, g.bboxDefined)
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}
// JSON is the json representation of the object. This might not be exactly the same as the original.
func (g Polygon) JSON() string {
return string(g.appendJSON(nil))
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}
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// String returns a string representation of the object. This might be JSON or something else.
func (g Polygon) String() string {
return g.JSON()
}
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func (g Polygon) bboxPtr() *BBox {
return g.BBox
}
func (g Polygon) hasPositions() bool {
if g.bboxDefined {
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return true
}
for _, c := range g.Coordinates {
if len(c) > 0 {
return true
}
}
return false
}
// WithinBBox detects if the object is fully contained inside a bbox.
func (g Polygon) WithinBBox(bbox BBox) bool {
if g.bboxDefined {
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return rectBBox(g.CalculatedBBox()).InsideRect(rectBBox(bbox))
}
if len(g.Coordinates) == 0 {
return false
}
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if g.BBox != nil {
if !rectBBox(*g.BBox).IntersectsRect(rectBBox(bbox)) {
return false
}
}
rbbox := rectBBox(bbox)
ext, holes := polyExteriorHoles(g.Coordinates)
if len(holes) > 0 {
if rbbox.Max == rbbox.Min {
return rbbox.Min.Inside(ext, holes)
}
return rbbox.Inside(ext, holes)
}
return ext.InsideRect(rectBBox(bbox))
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}
// IntersectsBBox detects if the object intersects a bbox.
func (g Polygon) IntersectsBBox(bbox BBox) bool {
if g.bboxDefined {
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return rectBBox(g.CalculatedBBox()).IntersectsRect(rectBBox(bbox))
}
if len(g.Coordinates) == 0 {
return false
}
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if g.BBox != nil {
if !rectBBox(*g.BBox).IntersectsRect(rectBBox(bbox)) {
return false
}
}
rbbox := rectBBox(bbox)
ext, holes := polyExteriorHoles(g.Coordinates)
if len(holes) > 0 {
if rbbox.Max == rbbox.Min {
return rbbox.Min.Intersects(ext, holes)
}
return rbbox.Intersects(ext, holes)
}
return ext.IntersectsRect(rectBBox(bbox))
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}
// Within detects if the object is fully contained inside another object.
func (g Polygon) Within(o Object) bool {
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return withinObjectShared(g, o,
func(v Polygon) bool {
if len(g.Coordinates) == 0 {
return false
}
return polyPositions(g.Coordinates[0]).Inside(polyExteriorHoles(v.Coordinates))
},
)
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}
// WithinCircle detects if the object is fully contained inside a circle.
func (g Polygon) WithinCircle(center Position, meters float64) bool {
if len(g.Coordinates) == 0 {
return false
}
for _, position := range g.Coordinates[0] {
if center.DistanceTo(position) >= meters {
return false
}
}
return true
}
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// Intersects detects if the object intersects another object.
func (g Polygon) Intersects(o Object) bool {
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return intersectsObjectShared(g, o,
func(v Polygon) bool {
if len(g.Coordinates) == 0 {
return false
}
return polyPositions(g.Coordinates[0]).Intersects(polyExteriorHoles(v.Coordinates))
},
)
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}
// IntersectsCircle detects if the object intersects a circle.
func (g Polygon) IntersectsCircle(center Position, meters float64) bool {
if g.Intersects(New2DPoint(center.X, center.Y)) {
return true
}
for _, polygon := range g.Coordinates {
for i := 0; i < len(polygon) - 1 ; i++ {
if SegmentIntersectsCircle(polygon[i], polygon[i + 1], center, meters) {
return true
}
}
}
return false
}
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// Nearby detects if the object is nearby a position.
func (g Polygon) Nearby(center Position, meters float64) bool {
return nearbyObjectShared(g, center.X, center.Y, meters)
}
// IsBBoxDefined returns true if the object has a defined bbox.
func (g Polygon) IsBBoxDefined() bool {
return g.bboxDefined
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}
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// IsGeometry return true if the object is a geojson geometry object. false if it something else.
func (g Polygon) IsGeometry() bool {
return true
}
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// Clip returns the object obtained by clipping this object by a bbox.
func (g Polygon) Clipped(bbox BBox) Object {
var new_coordinates [][]Position
for _, ring := range g.Coordinates {
new_coordinates = append(new_coordinates, ClipRing(ring, bbox))
}
res, _ := fillPolygon(new_coordinates, nil, nil)
return res
}