code: public GVRRenderData setCullFace(GVRCullFaceEnum cullFace, int passIndex) {
          if (passIndex < mRenderPassList.size()) {
              mRenderPassList.get(passIndex).setCullFace(cullFace);
          } else {
              Log.e(TAG, "Trying to set cull face to a invalid pass. Pass " + passIndex + " was not created.");
          }
          return this;
      }
docs: Set the face to be culled
  
  @param cullFace
  {@code GVRCullFaceEnum.Back} Tells Graphics API to discard
  back faces, {@code GVRCullFaceEnum.Front} Tells Graphics API
  to discard front faces, {@code GVRCullFaceEnum.None} Tells
  Graphics API to not discard any face
  @param passIndex
  The rendering pass to set cull face state