Add existing to tracked

node_modules/@cesium/engine/Source/Scene/KeyframeNode.js

@@ -0,0 +1,61 @@
+const LoadState = Object.freeze({
+  UNLOADED: 0, // Has no data and is in dormant state
+  RECEIVING: 1, // Is waiting on data from the provider
+  PROCESSING: 2, // Data received.  Contents are being processed for rendering.  Depending on the content, it might make its own requests for external data.
+  LOADED: 3, // Processed data from provider
+  FAILED: 4, // Failed to receive data from the provider
+  UNAVAILABLE: 5, // No data available for this tile
+});
+
+/**
+ * @alias KeyframeNode
+ * @constructor
+ *
+ * @param {SpatialNode} spatialNode
+ * @param {number} keyframe
+ *
+ * @private
+ */
+function KeyframeNode(spatialNode, keyframe) {
+  this.spatialNode = spatialNode;
+  this.keyframe = keyframe;
+  this.state = LoadState.UNLOADED;
+  this.content = undefined;
+  this.megatextureIndex = -1;
+  this.priority = -Number.MAX_VALUE;
+  this.highPriorityFrameNumber = -1;
+}
+
+/**
+ * Frees the resources used by this object.
+ * @private
+ */
+KeyframeNode.prototype.unload = function () {
+  this.content = this.content && this.content.destroy();
+
+  this.spatialNode = undefined;
+  this.state = LoadState.UNLOADED;
+  this.megatextureIndex = -1;
+  this.priority = -Number.MAX_VALUE;
+  this.highPriorityFrameNumber = -1;
+};
+
+/**
+ * @param {KeyframeNode} a
+ * @param {KeyframeNode} b
+ */
+KeyframeNode.priorityComparator = function (a, b) {
+  return a.priority - b.priority;
+};
+
+/**
+ * @param {KeyframeNode} a
+ * @param {KeyframeNode} b
+ */
+KeyframeNode.searchComparator = function (a, b) {
+  return a.keyframe - b.keyframe;
+};
+
+KeyframeNode.LoadState = LoadState;
+
+export default KeyframeNode;