Function usePointPicking

src/hooks/pointCloud/usePointPicking.ts:42–207

(params: UsePointPickingParams)

 * @returns Refs and handlers for point picking
 */
export function usePointPicking(params: UsePointPickingParams): UsePointPickingResult {
  const {
    pickingMode,
    selectedPointsLength,
    pointSize,
    indexToPoint3DIdRef,
    addSelectedPoint,
    setHoveredPoint,
  } = params;

  const { camera, gl, raycaster } = useThree();
  const pointsRef = useRef<THREE.Points>(null);

  // Manual raycasting state (avoids Three.js auto-raycasting on every pointer move)
  const mouseRef = useRef(new THREE.Vector2());
  const lastHoverTimeRef = useRef(0);
  const hoverDirtyRef = useRef(false);

  // Reusable ref for result (avoid allocations in hot path)
  const resultWorldPosRef = useRef(new THREE.Vector3());
  const lastHoverPosRef = useRef<THREE.Vector3 | null>(null);

  // Calculate max points based on picking mode
  const maxPoints = getRequiredPointCount(pickingMode);
  const needsMorePoints = needsMoreSelectedPoints(selectedPointsLength, pickingMode);

  // Find nearest point from intersections using pre-computed distanceToRay
  const findNearestPoint = useCallback(
    (intersections: THREE.Intersection[]): NearestPointResult | null => {
      const points = pointsRef.current;
      if (!points || intersections.length === 0) return null;

      let closestIdx = -1;
      let closestDist = Infinity;
      let closestWorldPos: THREE.Vector3 | null = null;

      // Must check all intersections - they're sorted by camera distance, not by distanceToRay
      for (let i = 0; i < intersections.length; i++) {
        const hit = intersections[i];
        if (hit.object !== points || hit.index === undefined) continue;

        const dist = hit.distanceToRay ?? Infinity;
        if (dist < closestDist) {
          closestDist = dist;
          closestIdx = hit.index;
          closestWorldPos = hit.point;
        }
      }

      if (closestIdx === -1 || !closestWorldPos) return null;
      resultWorldPosRef.current.copy(closestWorldPos);
      return { index: closestIdx, worldPos: resultWorldPosRef.current };
    },
    []
  );

  // DOM event listener for mouse tracking (no raycasting - just stores position)
  useEffect(() => {