Function pickPosition

packages/engine/Source/Scene/ScreenSpaceCameraController.js:1145–1183

(controller, mousePosition, result)

const scratchRayIntersection = new Cartesian3();

function pickPosition(controller, mousePosition, result) {
  const scene = controller._scene;
  const globe = controller._globe;
  const camera = scene.camera;

  let depthIntersection;
  if (scene.pickPositionSupported) {
    depthIntersection = scene.pickPositionWorldCoordinates(
      mousePosition,
      scratchDepthIntersection,
    );
  }

  if (!defined(globe)) {
    return Cartesian3.clone(depthIntersection, result);
  }

  const cullBackFaces = !controller._cameraUnderground;
  const ray = camera.getPickRay(mousePosition, pickGlobeScratchRay);
  const rayIntersection = globe.pickWorldCoordinates(
    ray,
    scene,
    cullBackFaces,
    scratchRayIntersection,
  );

  const pickDistance = defined(depthIntersection)
    ? Cartesian3.distance(depthIntersection, camera.positionWC)
    : Number.POSITIVE_INFINITY;
  const rayDistance = defined(rayIntersection)
    ? Cartesian3.distance(rayIntersection, camera.positionWC)
    : Number.POSITIVE_INFINITY;

  if (pickDistance < rayDistance) {
    return Cartesian3.clone(depthIntersection, result);
  }

  return Cartesian3.clone(rayIntersection, result);
}

const scratchDistanceCartographic = new Cartographic();