Add check for polygons/multipolygons

Author: kgiann78

measurement/measurement.go

@@ -11,7 +11,7 @@ import (
 	"github.com/tomchavakis/turf-go/geojson/geometry"
 	"github.com/tomchavakis/turf-go/internal/common"
 	"github.com/tomchavakis/turf-go/invariant"
-	meta "github.com/tomchavakis/turf-go/meta/coordAll"
+	"github.com/tomchavakis/turf-go/meta/coordAll"
 )
 
 // Distance calculates the distance between two points in kilometers. This uses the Haversine formula
@@ -825,20 +825,10 @@ func pointOnFeatureCollection(t interface{}, cent geometry.Point) bool {
 			}
 		}
 	case geometry.Polygon:
-		for _, c := range gtp.Coordinates {
-			//todo: decide if cent is on surface
-			print(len(c.Coordinates))
-		}
-		onSurface = true
 	case geometry.MultiPolygon:
-		coords := gtp.Coordinates
-		for _, coord := range coords {
-			for _, pl := range coord.Coordinates {
-				//todo: decide if cent is on surface
-				print(len(pl.Coordinates))
-			}
+		if pointOnPolygon(cent, gtp) {
+			onSurface = true
 		}
-		onSurface = true
 	}
 
 	return onSurface || onBorderOrPoint
@@ -850,3 +840,80 @@ func pointOnSegment(x float64, y float64, x1 float64, y1 float64, x2 float64, y2
 	var pb = math.Sqrt((x2 - x) * (x2 - x) + (y2 - y) * (y2 - y))
 	return ab == (ap + pb)
 }
+
+func pointOnPolygon(point geometry.Point, t interface{}) bool {
+	switch gpt := t.(type) {
+	case geometry.Polygon:
+		bbox, err := BBox(gpt)
+		if err != nil || len(bbox) == 0 || !inBBox(point, bbox) {
+			return false
+		}
+		return pointOnMultipolygon(point, []geometry.Polygon{gpt})
+	case geometry.MultiPolygon:
+		bbox, err := BBox(gpt)
+		if err != nil || len(bbox) == 0 || !inBBox(point, bbox) {
+			return false
+		}
+		return pointOnMultipolygon(point, gpt.Coordinates)
+	}
+
+	return false
+}
+
+func pointOnMultipolygon(point geometry.Point, polys []geometry.Polygon) bool {
+
+	insidePoly := false;
+	for i := 0; i < len(polys) && !insidePoly; i++ {
+		// check if it is in the outer ring first
+		if inRing(point, polys[i].Coordinates[0].Coordinates, false) {
+			inHole := false;
+			// check for the point in any of the holes
+			for j := 1; j < len(polys[i].Coordinates) && !inHole; j++ {
+				if inRing(point, polys[i].Coordinates[j].Coordinates, false) {
+					inHole = true;
+				}
+			}
+			if !inHole {
+				insidePoly = true;
+			}
+		}
+	}
+
+	return insidePoly
+}
+
+func inBBox(point geometry.Point, bbox []float64) bool {
+	return bbox[0] <= point.Lng && bbox[1] <= point.Lat && bbox[2] >= point.Lng && bbox[3] >= point.Lat
+}
+
+func inRing(point geometry.Point, ring []geometry.Point, ignoreBoundary bool) bool {
+	isInside := false
+
+	// remove last element if they are the same
+	if ring[0].Lat == ring[len(ring) - 1].Lat &&  ring[0].Lng == ring[len(ring) - 1].Lng {
+		ring = ring[:len(ring) - 1]
+	}
+
+	for i, j := 0, len(ring) - 1 ; i < len(ring); i, j = i+1, i {
+		xi := ring[i].Lng
+		yi := ring[i].Lat
+		xj := ring[j].Lng
+		yj := ring[j].Lat
+
+		onBoundary := point.Lat * (xi - xj) + yi * (xj - point.Lng) + yj * (point.Lng - xi) == 0 &&
+			(xi - point.Lng) * (xj - point.Lng) <= 0 &&
+			(yi - point.Lat) * (yj - point.Lat) <= 0
+
+		if onBoundary {
+			return !ignoreBoundary
+		}
+
+		intersect := (yi > point.Lat) != (yj > point.Lat) &&
+			(point.Lng < ((xj - xi) * (point.Lat - yi)) / (yj - yi) + xi)
+
+		if intersect {
+			isInside = !isInside
+		}
+	}
+	return isInside
+}

measurement/measurement_test.go

@@ -1560,3 +1560,171 @@ func TestRhumbDistance(t *testing.T) {
 		})
 	}
 }
+
+func TestInBBox(t *testing.T)  {
+	tests := map[string]struct {
+		point   geometry.Point
+		bbox    []float64
+		want    bool
+	}{
+		"point in bbox": {
+			point:	geometry.Point{
+				Lng: 116.0,
+				Lat: -20.0,
+			},
+			bbox: []float64{
+				113.0, -39.0, 154.0, -15.0,
+			},
+			want: true,
+		},
+		"point on bbox": {
+			point:	geometry.Point{
+				Lng: 116.0,
+				Lat: -20.0,
+			},
+			bbox: []float64{
+				116.0, -20.0, 154.0, -15.0,
+			},
+			want: true,
+		},
+		"point not in bbox": {
+			point:	geometry.Point{
+				Lng: -20.0,
+				Lat: 116.0,
+			},
+			bbox: []float64{
+				113.0, -39.0, 154.0, -15.0,
+			},
+			want: false,
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, tt.want, inBBox(tt.point, tt.bbox))
+		})
+	}
+}
+
+
+func TestInRing(t *testing.T) {
+	tests := map[string]struct {
+		point   geometry.Point
+		ring    []geometry.Point
+		want    bool
+	} {
+		"point in ring": {
+			point: geometry.Point{
+				Lng: 50.0,
+				Lat: 50.0,
+			},
+			ring: []geometry.Point {
+				{
+					Lng: 0.0,
+					Lat: 0.0,
+				},
+				{
+					Lng: 0.0,
+					Lat: 100.0,
+				},
+				{
+					Lng: 100.0,
+					Lat: 100.0,
+				},
+				{
+					Lng: 100.0,
+					Lat: 0.0,
+				},
+				{
+					Lng: 0.0,
+					Lat: 0.0,
+				},
+			},
+			want: true,
+		},
+		"point not in ring": {
+			point: geometry.Point{
+				Lng: -50.0,
+				Lat: -50.0,
+			},
+			ring: []geometry.Point {
+				{
+					Lng: 0.0,
+					Lat: 0.0,
+				},
+				{
+					Lng: 0.0,
+					Lat: 100.0,
+				},
+				{
+					Lng: 100.0,
+					Lat: 100.0,
+				},
+				{
+					Lng: 100.0,
+					Lat: 0.0,
+				},
+				{
+					Lng: 0.0,
+					Lat: 0.0,
+				},
+			},
+			want: false,
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, inRing(tt.point, tt.ring, false), tt.want)
+		})
+	}
+}
+
+
+func TestInPolygon(t *testing.T) {
+	tests := map[string]struct {
+		point   geometry.Point
+		polygon    geometry.Polygon
+		want    bool
+	} {
+		"point in polygon": {
+			point: geometry.Point{
+				Lng: 2.0,
+				Lat: 102.0,
+			},
+			polygon: geometry.Polygon {
+				Coordinates: []geometry.LineString{
+					{
+						Coordinates: []geometry.Point{
+							{
+								Lat: 2.0,
+								Lng: 102.0,
+							},
+							{
+								Lat: 2.0,
+								Lng: 103.0,
+							},
+							{
+								Lat: 3.0,
+								Lng: 103.0,
+							},
+							{
+								Lat: 3.0,
+								Lng: 102.0,
+							},
+							{
+								Lat: 2.0,
+								Lng: 102.0,
+							},
+						},
+					},
+				},
+			},
+			want: true,
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, pointOnPolygon(tt.point, tt.polygon), tt.want)
+		})
+	}
+}