牆朝向：牆的法向量在外牆面的投影。。
方向向量 cross product basisZ==normal vector ==orientation
the normal vector projected from the exterior side of the wallfac
familyinstance: door window ==》只與自身族有關 帶門面板的爲facingOrientation 與原始族同則爲正 反正爲負數
門框爲HandOrientation 與原始族同則爲正 反正爲負數