Function pickImageryHelper

packages/engine/Source/Scene/ImageryLayerCollection.js:347–419

(scene, pickedLocation, pickFeatures, callback)

const applicableRectangleScratch = new Rectangle();

function pickImageryHelper(scene, pickedLocation, pickFeatures, callback) {
  // Find the terrain tile containing the picked location.
  const tilesToRender = scene.globe._surface._tilesToRender;
  let pickedTile;

  for (
    let textureIndex = 0;
    !defined(pickedTile) && textureIndex < tilesToRender.length;
    ++textureIndex
  ) {
    const tile = tilesToRender[textureIndex];
    if (Rectangle.contains(tile.rectangle, pickedLocation)) {
      pickedTile = tile;
    }
  }

  if (!defined(pickedTile)) {
    return;
  }

  // Pick against all attached imagery tiles containing the pickedLocation.
  const imageryTiles = pickedTile.data.imagery;

  for (let i = imageryTiles.length - 1; i >= 0; --i) {
    const terrainImagery = imageryTiles[i];
    const imagery = terrainImagery.readyImagery;
    if (!defined(imagery)) {
      continue;
    }
    if (!imagery.imageryLayer.ready) {
      continue;
    }
    const provider = imagery.imageryLayer.imageryProvider;
    if (pickFeatures && !defined(provider.pickFeatures)) {
      continue;
    }

    if (!Rectangle.contains(imagery.rectangle, pickedLocation)) {
      continue;
    }

    // If this imagery came from a parent, it may not be applicable to its entire rectangle.
    // Check the textureCoordinateRectangle.
    const applicableRectangle = applicableRectangleScratch;

    const epsilon = 1 / 1024; // 1/4 of a pixel in a typical 256x256 tile.
    applicableRectangle.west = CesiumMath.lerp(
      pickedTile.rectangle.west,
      pickedTile.rectangle.east,
      terrainImagery.textureCoordinateRectangle.x - epsilon,
    );
    applicableRectangle.east = CesiumMath.lerp(
      pickedTile.rectangle.west,
      pickedTile.rectangle.east,
      terrainImagery.textureCoordinateRectangle.z + epsilon,
    );
    applicableRectangle.south = CesiumMath.lerp(
      pickedTile.rectangle.south,