init

src/worldState.js

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+import { Vector3, Quaternion } from 'three';
+import { Geodetic, PointOfView, radians } from '@takram/three-geospatial';
+
+const EARTH_RADIUS = 6378137;
+
+export const worldState = {
+  position: new Vector3(0, EARTH_RADIUS + 100000, 0),
+  quaternion: new Quaternion(),
+  speed: 1000.0,
+  stageRotationY: 0,
+};
+
+// Pre-allocated temp objects (avoid GC in useFrame)
+const _up = new Vector3();
+const _quat = new Quaternion();
+const _unitY = new Vector3(0, 1, 0);
+
+export function getSurfaceBasis(position) {
+  if (!position) return _quat.identity();
+  _up.copy(position).normalize();
+  if (_up.lengthSq() < 0.1) return _quat.identity();
+  return _quat.setFromUnitVectors(_unitY, _up);
+}
+
+// Non-mutating version for cases that need a copy
+const _basisOut = new Quaternion();
+export function getSurfaceBasisCopy(position) {
+  getSurfaceBasis(position);
+  return _basisOut.copy(_quat);
+}
+
+export function getEllipsoidRadius(position) {
+  const a = 6378137.0;
+  const b = 6356752.314245;
+  const r = position.length();
+  if (r < 100) return a;
+  const sinPhi = position.z / r;
+  const cosPhi = Math.sqrt(1 - sinPhi * sinPhi);
+  const aCos = a * cosPhi;
+  const bSin = b * sinPhi;
+  return Math.sqrt(
+    ((a * aCos) ** 2 + (b * bSin) ** 2) / (aCos ** 2 + bSin ** 2)
+  );
+}
+
+export const LOCATIONS = [
+  { name: 'Tokyo', longitude: 139.7671, latitude: 35.6812, heading: 180, pitch: -5, distance: 1100 },
+  { name: 'Fuji', longitude: 138.7278, latitude: 35.3206, heading: 0, pitch: -10, distance: 4000 },
+  { name: 'Space', longitude: 139.7671, latitude: 35.6812, heading: 0, pitch: -90, distance: 100000 },
+];
+
+export function teleportTo(location) {
+  const { longitude, latitude, heading, pitch, distance } = location;
+  const position = new Vector3();
+  const globalQuaternion = new Quaternion();
+  const up = new Vector3(0, 1, 0);
+
+  const truePosition = new Geodetic(radians(longitude), radians(latitude), distance).toECEF();
+
+  new PointOfView(distance, radians(heading), radians(pitch)).decompose(
+    new Geodetic(radians(longitude), radians(latitude)).toECEF(),
+    position,
+    globalQuaternion,
+    up
+  );
+
+  worldState.position.copy(truePosition);
+
+  const basis = getSurfaceBasisCopy(truePosition);
+  worldState.quaternion.copy(basis.invert().multiply(globalQuaternion));
+}