feat: initialize drainage network frontend

2026-07-10 16:16:17 +08:00
commit 66de96d9e4
133 changed files with 33057 additions and 0 deletions
@@ -0,0 +1,96 @@
+export type LngLatTuple = [number, number];
+
+const EARTH_RADIUS_METERS = 6371008.8;
+const SAME_COORDINATE_EPSILON = 0.0000001;
+
+export function getDistanceMeters(from: LngLatTuple, to: LngLatTuple) {
+  const fromLatitude = toRadians(from[1]);
+  const toLatitude = toRadians(to[1]);
+  const deltaLatitude = toRadians(to[1] - from[1]);
+  const deltaLongitude = toRadians(to[0] - from[0]);
+  const a =
+    Math.sin(deltaLatitude / 2) ** 2 +
+    Math.cos(fromLatitude) * Math.cos(toLatitude) * Math.sin(deltaLongitude / 2) ** 2;
+
+  return 2 * EARTH_RADIUS_METERS * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+}
+
+export function getLineDistanceMeters(coordinates: LngLatTuple[]) {
+  return coordinates.reduce((total, coordinate, index) => {
+    if (index === 0) {
+      return total;
+    }
+
+    return total + getDistanceMeters(coordinates[index - 1], coordinate);
+  }, 0);
+}
+
+export function getLastSegmentDistanceMeters(coordinates: LngLatTuple[]) {
+  if (coordinates.length < 2) {
+    return 0;
+  }
+
+  return getDistanceMeters(coordinates[coordinates.length - 2], coordinates[coordinates.length - 1]);
+}
+
+export function getPolygonAreaSquareMeters(coordinates: LngLatTuple[]) {
+  if (coordinates.length < 3) {
+    return 0;
+  }
+
+  const closedCoordinates = [...coordinates, coordinates[0]];
+  const area = closedCoordinates.slice(0, -1).reduce((total, coordinate, index) => {
+    const nextCoordinate = closedCoordinates[index + 1];
+    return (
+      total +
+      toRadians(nextCoordinate[0] - coordinate[0]) *
+        (2 + Math.sin(toRadians(coordinate[1])) + Math.sin(toRadians(nextCoordinate[1])))
+    );
+  }, 0);
+
+  return Math.abs((area * EARTH_RADIUS_METERS * EARTH_RADIUS_METERS) / 2);
+}
+
+export function createCircleCoordinates(center: LngLatTuple, radiusMeters: number, steps = 48) {
+  const angularDistance = radiusMeters / EARTH_RADIUS_METERS;
+  const centerLongitude = toRadians(center[0]);
+  const centerLatitude = toRadians(center[1]);
+  const coordinates: LngLatTuple[] = [];
+
+  for (let index = 0; index <= steps; index += 1) {
+    const bearing = (2 * Math.PI * index) / steps;
+    const latitude = Math.asin(
+      Math.sin(centerLatitude) * Math.cos(angularDistance) +
+        Math.cos(centerLatitude) * Math.sin(angularDistance) * Math.cos(bearing)
+    );
+    const longitude =
+      centerLongitude +
+      Math.atan2(
+        Math.sin(bearing) * Math.sin(angularDistance) * Math.cos(centerLatitude),
+        Math.cos(angularDistance) - Math.sin(centerLatitude) * Math.sin(latitude)
+      );
+
+    coordinates.push([toDegrees(longitude), toDegrees(latitude)]);
+  }
+
+  return coordinates;
+}
+
+export function isSameCoordinate(previous: LngLatTuple | undefined, next: LngLatTuple) {
+  if (!previous) {
+    return false;
+  }
+
+  return (
+    Math.abs(previous[0] - next[0]) < SAME_COORDINATE_EPSILON &&
+    Math.abs(previous[1] - next[1]) < SAME_COORDINATE_EPSILON
+  );
+}
+
+export function toRadians(value: number) {
+  return (value * Math.PI) / 180;
+}
+
+function toDegrees(value: number) {
+  return (value * 180) / Math.PI;
+}