code: function HSHG() {
  
      this.MAX_OBJECT_CELL_DENSITY = 1 / 8; // objects / cells
      this.INITIAL_GRID_LENGTH = 256; // 16x16
      this.HIERARCHY_FACTOR = 2;
      this.HIERARCHY_FACTOR_SQRT = Math.SQRT2;
      this.UPDATE_METHOD = update_RECOMPUTE; // or update_REMOVEALL
  
      this._grids = [];
      this._globalObjects = [];
  }
docs: --------------------------------------------------------------------- ENTITIES ---------------------------------------------------------------------