高级B-rep是一种边界表示模型，其中所有的面、边和顶点都被显式地表示出来。它是一个具有明确拓扑结构和基本或自由形式几何体的实体。B-rep的面属于IfcAdvancedFace类型。高级B-rep必须满足与流形实体B-rep相同的拓扑约束。
注：引入高级B-rep是为了支持越来越多的应用程序，这些应用程序可以定义和交换基于NURBS或其他B样条曲线曲面的B-rep模型。
上图说明了IfcAdvancedBrep在具有b样条曲面的边界表示模型中的使用。该图显示了基于IfcAdvancedFace的高级B-rep所使用的拓扑和几何表示项。
注：实体改编自ISO 10303-514中定义的高级形状表示法。
IFC4中增加的新实体
非正式提议：
①每个面都是一个面；
②每个面都有一个基本面、扫掠面或b样条曲面定义的几何体；
③用于定义面的边界的边缘应全部参考边缘曲线
④用于定义面的几何图形和面边界的每条曲线应为圆锥曲线、直线、折线或b样条曲线
⑤用于定义面边界的边应全部由顶点类型的顶点修剪
⑥用于定义面边界的循环不能是定向子类型
| # | 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 | |||||
| IfcSolidModel | |||||
| Dim :=3 |
IfcDimensionCount | [1:1] | The space dimensionality of this class, it is always 3. | X | |
| IfcManifoldSolidBrep | |||||
| 1 | Outer | IfcClosedShell | [1:1] | A closed shell defining the exterior boundary of the solid. The shell normal shall point away from the interior of the solid. | X |
| IfcAdvancedBrep | |||||
ENTITY IfcAdvancedBrep SUPERTYPE OF(IfcAdvancedBrepWithVoids) SUBTYPE OF (IfcManifoldSolidBrep); WHERE HasAdvancedFaces : SIZEOF(QUERY(Afs <* SELF\IfcManifoldSolidBrep.Outer.CfsFaces | (NOT (‘IFCTOPOLOGYRESOURCE.IFCADVANCEDFACE‘ IN TYPEOF(Afs))) )) = 0; END_ENTITY;
原文：https://www.cnblogs.com/herd/p/13449560.html