code: function RenderingGroup(index, scene, opaqueSortCompareFn, alphaTestSortCompareFn, transparentSortCompareFn) {
              if (opaqueSortCompareFn === void 0) { opaqueSortCompareFn = null; }
              if (alphaTestSortCompareFn === void 0) { alphaTestSortCompareFn = null; }
              if (transparentSortCompareFn === void 0) { transparentSortCompareFn = null; }
              this.index = index;
              this._opaqueSubMeshes = new BABYLON.SmartArray(256);
              this._transparentSubMeshes = new BABYLON.SmartArray(256);
              this._alphaTestSubMeshes = new BABYLON.SmartArray(256);
              this._depthOnlySubMeshes = new BABYLON.SmartArray(256);
              this._particleSystems = new BABYLON.SmartArray(256);
              this._spriteManagers = new BABYLON.SmartArray(256);
              this._edgesRenderers = new BABYLON.SmartArray(16);
              this._scene = scene;
              this.opaqueSortCompareFn = opaqueSortCompareFn;
              this.alphaTestSortCompareFn = alphaTestSortCompareFn;
              this.transparentSortCompareFn = transparentSortCompareFn;
          }
docs: Creates a new rendering group.
  @param index The rendering group index
  @param opaqueSortCompareFn The opaque sort comparison function. If null no order is applied
  @param alphaTestSortCompareFn The alpha test sort comparison function. If null no order is applied
  @param transparentSortCompareFn The transparent sort comparison function. If null back to front + alpha index sort is applied