Don't use turf to measure shortcut length

backend/src/shortcuts.rs

@@ -120,10 +120,12 @@ impl Path {
                 pts.extend(rev);
             }
         }
-        let mut f = Feature::from(Geometry::from(
-            &map.mercator.to_wgs84(&LineString::new(pts)),
-        ));
+        let linestring = LineString::new(pts);
+
+        let length = linestring.euclidean_length();
+        let mut f = Feature::from(Geometry::from(&map.mercator.to_wgs84(&linestring)));
         f.set_property("directness", self.directness);
+        f.set_property("length_meters", length);
         f
     }
 }

web/package.json

@@ -31,7 +31,6 @@
     "@maptiler/geocoding-control": "^1.2.2",
     "@picocss/pico": "^2.0.3",
     "@turf/along": "^6.5.0",
-    "@turf/length": "^6.5.0",
     "maplibre-draw-polygon": "github:dabreegster/maplibre-draw-polygon",
     "route-snapper": "^0.4.0",
     "svelte-maplibre": "^0.8.3"

web/src/AnimatePaths.svelte

@@ -1,12 +1,15 @@
 <script lang="ts">
-  import turfLength from "@turf/length";
   import along from "@turf/along";
   import { layerId } from "./common";
   import type { FeatureCollection, LineString } from "geojson";
   import { GeoJSON, CircleLayer } from "svelte-maplibre";
   import { onDestroy } from "svelte";
 
-  export let paths: FeatureCollection<LineString, { directness: number }>;
+  export let paths: FeatureCollection<
+    LineString,
+    { directness: number; length_meters: number }
+  >;
+
   let totalDirectness = sumWeights();
 
   let numDots = 50;
@@ -15,7 +18,6 @@
 
   interface Dot {
     idx: number;
-    length: number;
     distance: number;
   }
 
@@ -53,7 +55,6 @@
       if (rand < cumulativeWeight) {
         return {
           idx,
-          length: turfLength(path, { units: "kilometers" }),
           distance: 0,
         };
       }
@@ -75,7 +76,10 @@
   function animate() {
     for (let [idx, dot] of dots.entries()) {
       dot.distance += stepKm;
-      if (dot.distance >= dot.length) {
+      if (
+        dot.distance >=
+        paths.features[dot.idx].properties.length_meters / 1000
+      ) {
         dots[idx] = startDot();
       }
     }