fn add_piece(
parent: &EndCityPiece,
offset: IVec3,
template_name: &str,
rotation: Rotation,
overwrite: bool,
) -> EndCityPieceExpand description
Vanilla’s addPiece. With pivot=ZERO and mirror=NONE,
calculateConnectedPosition reduces to rotate(offset, parent.rotation)
added to the parent’s template position.