public SceneStreaming(string fileName, int length)
 {
     state             = State.Unloaded;
     this.fileName     = fileName;
     this.length       = length;
     generateAsyncFunc = GenerateAsync;
     deleteAsyncFunc   = DeleteAsync;
     deleteCommand     = new LoadCommand
     {
         isInitialized = false,
         initFunc      = DeleteInit,
         load          = DeleteRun
     };
     generateCommand = new LoadCommand
     {
         isInitialized = false,
         initFunc      = GenerateInit,
         load          = GenerateRun
     };
 }
 public LinkNode(LoadCommand command)
 {
     this.command = command;
     nextLevel    = null;
     lastLevel    = null;
 }