Show routing demonstration on radar page.

tomtom/geojson.go

@@ -0,0 +1,27 @@
+package tomtom
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Convert a slice of points to GeoJSON
+func PolylineToGeoJSON(polyline []Point) string {
+	var sb strings.Builder
+
+	sb.WriteString(`{"type":"LineString","coordinates":[`)
+
+	for i, point := range polyline {
+		// IMPORTANT: GeoJSON uses [longitude, latitude] order!
+		sb.WriteString(fmt.Sprintf("[%g,%g]", point.Longitude, point.Latitude))
+
+		// Add comma if not the last point
+		if i < len(polyline)-1 {
+			sb.WriteString(",")
+		}
+	}
+
+	sb.WriteString("]}")
+
+	return sb.String()
+}