IfcFaceSurface

IfcFaceSurface

实体定义

注：定义依据ISO/CD 10303-42:1992

面曲面是由关联曲面定义几何图形的面的子类型。表面使用的表面部分应作为开放圆盘嵌入平面中，可能带有孔。但是，面与其边界循环的边和顶点的并集不需要嵌入在平面中。例如，它可能覆盖整个球体或圆环体。由于面和几何曲面都定义了法线方向，BOOLEAN标志（方向属性）用于指示曲面法线是否与面法线方向一致（TRUE）或相反（FALSE）。与面回路的任何组件相关的几何结构应与表面几何结构一致，即所有顶点和边曲线的域都包含在面几何结构表面中。一个曲面可以由多个面曲面引用。

注：适用于ISO 10303-42中定义的表面的实体。

历史IFC2x中的新实体

非正式提议：

1. 面曲面的域被正式定义为由循环修剪的面几何体的域，该域不包括边界循环。
2. 面曲面具有非零有限范围。
3. 面曲面是一个流形。
4. 面曲面是弧形连接的。
5. 面曲面具有曲面亏格0。
6. 循环不是面域的一部分。
7. 回路几何形状应与表面几何形状一致。这意味着，用于定义面表面边界循环的任何边曲线或顶点都应位于面几何体上。
8. 表面的环不得相交。

 

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
2	FaceSurface	IfcSurface	[1:1]	The surface which defines the internal shape of the face. This surface may be unbounded. The domain of the face is defined by this surface and the bounding loops in the inherited attribute SELF\FaceBounds.	X
3	SameSense	IfcBoolean	[1:1]	This flag indicates whether the sense of the surface normal agrees with (TRUE), or opposes (FALSE), the sense of the topological normal to the face.	X

 

 

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
IfcTopologicalRepresentationItem
IfcFace
1	Bounds	IfcFaceBound	S[1:?]	Boundaries of the face.	X
	HasTextureMaps	IfcTextureMap @MappedTo	S[0:?]		X
IfcFaceSurface
2	FaceSurface	IfcSurface	[1:1]	The surface which defines the internal shape of the face. This surface may be unbounded. The domain of the face is defined by this surface and the bounding loops in the inherited attribute SELF\FaceBounds.	X
3	SameSense	IfcBoolean	[1:1]	This flag indicates whether the sense of the surface normal agrees with (TRUE), or opposes (FALSE), the sense of the topological normal to the face.	X

 

 

EXPRESS Specification

ENTITY IfcFaceSurface
 SUPERTYPE OF(IfcAdvancedFace)
 SUBTYPE OF (IfcFace);
  FaceSurface : IfcSurface;
  SameSense : IfcBoolean;
END_ENTITY;

 

 

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