IfcCartesianPoint

IfcCartesianPoint通过正交右笛卡尔坐标系中的坐标定义点。在本规范中，仅使用二维和三维笛卡尔点。

注：定义根据ISO/CD 10303-42:1992

笛卡尔点是由其在直角笛卡尔坐标系或参数空间中的坐标定义的点。实体是在一个一维、二维或三维空间中定义的，由列表中的坐标数量决定。根据使用点的几何表示上下文，坐标的名称可以是（x，y，z）或（u，v），或任何其他选定的值。

注：实体改编自ISO 10303-42中定义的笛卡尔点

IFC1.0中增加的新实体

Formal Propositions

Rule	Description
CP2Dor3D	Only two or three dimensional points are in scope.

 

#	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
IfcPoint
IfcCartesianPoint
1	Coordinates	IfcLengthMeasure	L[1:3]	The first, second, and third coordinate of the point location. If placed in a two or three dimensional rectangular Cartesian coordinate system, Coordinates[1] is the X coordinate, Coordinates[2] is the Y coordinate, and Coordinates[3] is the Z coordinate.	X
	Dim :=HIINDEX(Coordinates)	IfcDimensionCount	[1:1]	The space dimensionality of this class, determined by the number of coordinates in the List of Coordinates.	X

EXPRESS Specification

ENTITY IfcCartesianPoint
 SUBTYPE OF (IfcPoint);
  Coordinates : LIST [1:3] OF IfcLengthMeasure;
 DERIVE
  Dim : IfcDimensionCount := HIINDEX(Coordinates);
 WHERE
  CP2Dor3D : HIINDEX(Coordinates) >= 2;
END_ENTITY;