IfcCartesianTransformationOperator2D

Posted 2020-12-11 herd

IfcCartesianTransformationOperator2D定义二维空间中的几何变换。

注释定义符合ISO/CD 10303-42:1992

笛卡尔变换算子2d定义了二维空间中由平移、旋转、镜像和均匀缩放组成的几何变换。规范化向量u的列表定义正交矩阵T的列。这些向量由基轴函数从方向属性axis1和axis2计算。如果| T |=-1，则转换包括镜像。

注：实体改编自ISO10303-42中定义的笛卡尔变换算子。

在IFC2x中增加的新实体。

Formal Propositions

Rule	Description
DimEqual2	The coordinate space dimensionality of this entity shall be 2.
Axis1Is2D	The inherited Axis1 should have (if given) the dimensionality of 2.
Axis2Is2D	The inherited Axis2 should have (if given) the dimensionality of 2.

 

 

 

 

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcRepresentationItem
	LayerAssignment	IfcPresentationLayerAssignment @AssignedItems	S[0:1]	Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.	X
	StyledByItem	IfcStyledItem @Item	S[0:1]	Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.	X
IfcGeometricRepresentationItem
IfcCartesianTransformationOperator
1	Axis1	IfcDirection	[0:1]	The direction used to determine U[1], the derived X axis direction.	X
2	Axis2	IfcDirection	[0:1]	The direction used to determine U[2], the derived Y axis direction.	X
3	LocalOrigin	IfcCartesianPoint	[1:1]	The required translation, specified as a cartesian point. The actual translation included in the transformation is from the geometric origin to the local origin.	X
4	Scale	IfcReal	[0:1]	The scaling value specified for the transformation.	X
	Scl :=NVL(Scale, 1.0)	IfcReal	[1:1]	The derived scale S of the transformation, equal to scale if that exists, or 1.0 otherwise.	X
	Dim :=LocalOrigin.Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, determined by the space dimensionality of the local origin.	X
IfcCartesianTransformationOperator2D
	U :=IfcBaseAxis(2,SELFIfcCartesianTransformationOperator.Axis1, SELFIfcCartesianTransformationOperator.Axis2,?)	IfcDirection	L[2:2]	The list of mutually orthogonal, normalized vectors defining the transformation matrix T. They are derived from the explicit attributes Axis1 and Axis2 in that order.	X

EXPRESS Specification

ENTITY IfcCartesianTransformationOperator2D
 SUPERTYPE OF(IfcCartesianTransformationOperator2DnonUniform)
 SUBTYPE OF (IfcCartesianTransformationOperator);
 DERIVE
  U : LIST [2:2] OF IfcDirection := IfcBaseAxis(2,SELFIfcCartesianTransformationOperator.Axis1, SELFIfcCartesianTransformationOperator.Axis2,?);
 WHERE
  DimEqual2 : SELFIfcCartesianTransformationOperator.Dim = 2;
  Axis1Is2D : NOT(EXISTS(SELFIfcCartesianTransformationOperator.Axis1)) OR (SELFIfcCartesianTransformationOperator.Axis1.Dim = 2);
  Axis2Is2D : NOT(EXISTS(SELFIfcCartesianTransformationOperator.Axis2)) OR (SELFIfcCartesianTransformationOperator.Axis2.Dim = 2);
END_ENTITY;