1语义定义
高级B-rep是一种边界表示模型，其中所有面、边和顶点都被显式表示。它是一个具有显式拓扑和基本或自由几何体的实体。B-rep的面类型为IfcAdvancedFace。高级B-rep必须满足与流形实体B-rep相同的拓扑约束。
注：已引入高级B-rep，以支持越来越多的应用程序，这些应用程序可以基于NURBS或其他B样条曲面定义和交换B-rep模型。
注：根据ISO 10303-514中定义的advanced_brep_shape_presentation改编的实体。
IFC4中的新实体
非正式提议：
- 每个面是面表面；
- 每个面表面具有由基本表面、扫掠表面或b样条表面定义的几何结构；
- 用于定义面的边界的边均应参考边曲线
- 用于定义面的几何图形和面边界的每条曲线应为二次曲线、直线、多段线或b样条曲线
- 用于定义面边界的边都应通过顶点类型的顶点进行修剪
- 用于定义面边界的任何环都不应是定向子类型
2实体继承
3实体属性
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRepresentationItem (2) | |||
| LayerAssignment | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems |
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. IFC2X3-CHANGE The inverse attribute LayerAssignments has been added.IFC4-CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. |
|
| StyledByItem | SET [0:1] OF IfcStyledItem FOR Item |
Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. IFC2X3-CHANGE The inverse attribute StyledByItem has been added. |
|
| IfcSolidModel (1) | |||
| * | Dim | IfcDimensionCount |
This attribute is formally derived. The space dimensionality of this class, it is always 3. |
| Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes | |||
| IfcManifoldSolidBrep (1) | |||
| 1 | Outer | IfcClosedShell |
A closed shell defining the exterior boundary of the solid. The shell normal shall point away from the interior of the solid. |
ENTITY IfcAdvancedBrep
SUPERTYPE OF (ONEOF
(IfcAdvancedBrepWithVoids))
SUBTYPE OF (IfcManifoldSolidBrep);
WHERE
HasAdvancedFaces : SIZEOF(QUERY(Afs <* SELF\IfcManifoldSolidBrep.Outer.CfsFaces |
(NOT ('IFC4X3.IFCADVANCEDFACE' IN TYPEOF(Afs)))
)) = 0;
END_ENTITY;
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标签：定义,attribute,rep,实体,IfcAdvancedBrep,LayerAssignments,ifc4x3,边界 From： https://www.cnblogs.com/herd/p/17168198.html