refactor: Simplify vegetation mesh strategies with Turf utilities

- TreeRowStrategy: Replace manual haversine distance calculation with @turf/line-chunk for cleaner interval-based point spacing
- vegetationUtils: Use @turf/bbox for bounding box calculation instead of manual min/max iteration
- vegetationUtils: Improve hash function precision (multiply by 1e6 instead of 1000)
- Both changes reduce complexity and leverage battle-tested geospatial libraries

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: 2 people

bun.lock

@@ -46,6 +46,7 @@
     "@kobalte/core": "^0.13.11",
     "@mapbox/vector-tile": "^2.0.4",
     "@turf/area": "^7.3.4",
+    "@turf/bbox": "^7.3.4",
     "@turf/bearing": "^7.3.4",
     "@turf/boolean-contains": "^7.3.4",
     "@turf/boolean-intersects": "^7.3.4",
@@ -55,6 +56,7 @@
     "@turf/helpers": "^7.3.4",
     "@turf/intersect": "^7.3.4",
     "@turf/length": "^7.3.4",
+    "@turf/line-chunk": "^7.3.4",
     "@turf/line-slice-along": "^7.3.4",
     "@turf/line-split": "^7.3.4",
     "@turf/point-grid": "^7.3.4",

package.json

@@ -1,10 +1,9 @@
 import type { VegetationVisual } from '../types';
 import { vegetationMeshConfig } from '../../../config';
-import { EARTH_RADIUS } from '../../../gis/GeoCoordinates';
 import type { IVegetationStrategy, TreePoint, BushPoint } from './types';
 import { BROADLEAF_COLORS, NEEDLELEAF_COLORS } from './vegetationUtils';
-
-const TO_RAD = Math.PI / 180;
+import lineChunk from '@turf/line-chunk';
+import { lineString } from '@turf/helpers';
 
 export class TreeRowStrategy implements IVegetationStrategy {
   collectPoints(
@@ -17,41 +16,27 @@ export class TreeRowStrategy implements IVegetationStrategy {
     if (coords.length < 2) return;
 
     const config = vegetationMeshConfig.treeRow;
-    const interval = config.intervalMeters;
     const isNeedle = veg.leafType === 'needleleaved';
     const colors = isNeedle ? NEEDLELEAF_COLORS : BROADLEAF_COLORS;
 
-    let accumulated = 0;
-
-    for (let i = 0; i < coords.length - 1; i++) {
-      const [lng1, lat1] = coords[i]!;
-      const [lng2, lat2] = coords[i + 1]!;
-
-      const midLat = (lat1 + lat2) / 2;
-      const cosLat = Math.cos(midLat * TO_RAD);
-      const dEast = (lng2 - lng1) * TO_RAD * EARTH_RADIUS * cosLat;
-      const dNorth = (lat2 - lat1) * TO_RAD * EARTH_RADIUS;
-      const segLen = Math.sqrt(dEast * dEast + dNorth * dNorth);
-      if (segLen < 0.1) continue;
-
-      const dLng = lng2 - lng1;
-      const dLat = lat2 - lat1;
-
-      while (accumulated < segLen) {
-        const t = accumulated / segLen;
-        trees.push({
-          lng: lng1 + dLng * t,
-          lat: lat1 + dLat * t,
-          trunkHeightMin: config.trunkHeightMin,
-          trunkHeightMax: config.trunkHeightMax,
-          crownRadiusMin: config.crownRadiusMin,
-          crownRadiusMax: config.crownRadiusMax,
-          isNeedle,
-          colors,
-        });
-        accumulated += interval;
-      }
-      accumulated -= segLen;
+    const chunks = lineChunk(lineString(coords), config.intervalMeters, {
+      units: 'meters',
+    });
+    for (const chunk of chunks.features) {
+      const start = chunk.geometry.coordinates[0];
+      if (!start || start[0] === undefined || start[1] === undefined) continue;
+      const lng = start[0];
+      const lat = start[1];
+      trees.push({
+        lng,
+        lat,
+        trunkHeightMin: config.trunkHeightMin,
+        trunkHeightMax: config.trunkHeightMax,
+        crownRadiusMin: config.crownRadiusMin,
+        crownRadiusMax: config.crownRadiusMax,
+        isNeedle,
+        colors,
+      });
     }
   }
 }

src/features/vegetation/meshStrategies/TreeRowStrategy.ts

@@ -8,6 +8,7 @@ import {
   Color,
   type Object3D,
 } from 'three';
+import bbox from '@turf/bbox';
 import booleanPointInPolygon from '@turf/boolean-point-in-polygon';
 import { point, polygon as turfPolygon } from '@turf/helpers';
 import pointGrid from '@turf/point-grid';
@@ -34,8 +35,8 @@ export const NEEDLELEAF_COLORS = ['#1a5020', '#205828', '#256030', '#1a4a20'];
 export const SCRUB_COLORS = ['#4a7a38', '#5a8a40', '#4a8030'];
 
 export function hash(x: number, y: number): number {
-  const a = Math.floor(x * 1000) & 0xffff;
-  const b = Math.floor(y * 1000) & 0xffff;
+  const a = Math.floor(x * 1e6);
+  const b = Math.floor(y * 1e6);
   return ((a * 73856093) ^ (b * 19349663)) & 0x7fffffff;
 }
 
@@ -74,16 +75,7 @@ export function distributeGridInPolygon(
   const ring = polygon.coordinates[0];
   if (!ring || ring.length < 4) return [];
 
-  let minLng = Infinity,
-    maxLng = -Infinity;
-  let minLat = Infinity,
-    maxLat = -Infinity;
-  for (const [lng, lat] of ring as [number, number][]) {
-    if (lng < minLng) minLng = lng;
-    if (lng > maxLng) maxLng = lng;
-    if (lat < minLat) minLat = lat;
-    if (lat > maxLat) maxLat = lat;
-  }
+  const [minLng, minLat, maxLng, maxLat] = bbox(polygon);
 
   const grid = pointGrid([minLng, minLat, maxLng, maxLat], spacingX, {
     units: 'meters',