IfcBoundingBox

IfcBoundingBox定义了一个与定义它的对象坐标系的轴平行的正交长方体。它是由一个角点定义的，角点是三维笛卡尔点，三个长度度量值定义盒子在正轴方向上的X、Y和Z参数。

注意，具有产品形状表示的IfcProduct的任何子类型都可能具有边界框表示。在IfcShapeRepresentation中定义的“Box”表示标识符使用IfcBoundingBox作为最简单的三维形状表示。

如图所示，IfcBoundingBox定义有自己的位置，可以用来相对于几何坐标系放置IfcBoundingBox。IfcBoundingBox由左下角（角）和右上角（在父坐标系中测量的XDim、YDim和ZDim）定义。

#	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
IfcBoundingBox
1	Corner	IfcCartesianPoint	[1:1]	Location of the bottom left corner (having the minimum values).	X
2	XDim	IfcPositiveLengthMeasure	[1:1]	Length attribute (measured along the edge parallel to the X Axis)	X
3	YDim	IfcPositiveLengthMeasure	[1:1]	Width attribute (measured along the edge parallel to the Y Axis)	X
4	ZDim	IfcPositiveLengthMeasure	[1:1]	Height attribute (measured along the edge parallel to the Z Axis).	X
	Dim :=3	IfcDimensionCount	[1:1]	The space dimensionality of this class, it is always 3.	X

EXPRESS Specification

ENTITY IfcBoundingBox
 SUBTYPE OF (IfcGeometricRepresentationItem);
  Corner : IfcCartesianPoint;
  XDim : IfcPositiveLengthMeasure;
  YDim : IfcPositiveLengthMeasure;
  ZDim : IfcPositiveLengthMeasure;
 DERIVE
  Dim : IfcDimensionCount := 3;
END_ENTITY;