uad_x * 2,     quad_y * 2);
                    this._renderSubdividedPatchesRecursive(ctx, tr, currentLevel + 1, targetMaxLevel, quad_x * 2 + 1, quad_y * 2);
                    this._renderSubdividedPatchesRecursive(ctx, bl, currentLevel + 1, targetMaxLevel, quad_x * 2,     quad_y * 2 + 1);
                    this._renderSubdividedPatchesRecursive(ctx, br, currentLevel + 1, targetMaxLevel, quad_x * 2 + 1, quad_y * 2 + 1);
                }
            }

            _renderFilledSubdivisionPathsRecursive