IfcAxis2Placement3D定义了三维空间中物体的位置和方向,由三部分组成: The attribute Axis defines the Z direction, RefDirection the X direction. The Y direction is derived. 注:Y轴方向由X轴和Z轴方向通过外积计算获得. 当Axis和RefDirection未定义时,X轴为P[1] ,默认值 [1.,0.,0.].Y轴为P[2],默认值为[0.,1.,0.].Z轴为P[3] ,默…