Is Long/Lat within Polygon from GeoJson

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package main

import (
    "fmt"
    "io/ioutil"

    "github.com/paulmach/orb"
    "github.com/paulmach/orb/geojson"
    "github.com/paulmach/orb/planar"
)

const (
    GEO_FILE = "points.geojson"
)

func main() {

    // Load in our geojson file into a feature collection
    b, _ := ioutil.ReadFile(GEO_FILE)
    featureCollection, _ := geojson.UnmarshalFeatureCollection(b)

    // Pass in the feature collection + a point of Long/Lat
    if isPointInsidePolygon(featureCollection, orb.Point{100.5, 0.5}) {
        fmt.Println("Point 1 is inside a Polygon")
    } else {
        fmt.Println("Point 1 is not found inside Polygon")
    }

    if isPointInsidePolygon(featureCollection, orb.Point{105.5, 2.5}) {
        fmt.Println("Point 2 is inside a Polygon")
    } else {
        fmt.Println("Point 2 is not found inside Polygon")
    }
}

// isPointInsidePolygon runs through the MultiPolygon and Polygons within a 
// feature collection and checks if a point (long/lat) lies within it.
func isPointInsidePolygon(fc *geojson.FeatureCollection, point orb.Point) bool {
    for _, feature := range fc.Features {
        // Try on a MultiPolygon to begin
        multiPoly, isMulti := feature.Geometry.(orb.MultiPolygon)
        if isMulti {
            if planar.MultiPolygonContains(multiPoly, point) {
                return true
            }
        } else {
            // Fallback to Polygon
            polygon, isPoly := feature.Geometry.(orb.Polygon)
            if isPoly {
                if planar.PolygonContains(polygon, point) {
                    return true
                }
            }
        }
    }
    return false
}