function TextureManager() {
  this._defaultTexture = undefined;
  this._textures = {};
  this._loadedImages = [];

  // Keep track of the last time update() was called to avoid
  // calling update() twice.
  this._lastUpdatedFrame = -1;
}
An object to manage loading textures

@alias TextureManager
@constructor

@private
@experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.