IfcCsgPrimitive3D是所有三维原型的抽象超类型，用作树根项或CSG实体模型中的布尔结果。所有三维CSG基元都是在三维放置坐标系中定义的。
| # | 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 | |||||
| IfcCsgPrimitive3D | |||||
| 1 | Position | IfcAxis2Placement3D | [1:1] | The placement coordinate system to which the parameters of each individual CSG primitive apply. | X |
| Dim :=3 |
IfcDimensionCount | [1:1] | The space dimensionality of this geometric representation item, it is always 3. | X | |
ENTITY IfcCsgPrimitive3D
ABSTRACT SUPERTYPE OF(ONEOF(IfcBlock, IfcRectangularPyramid, IfcRightCircularCone, IfcRightCircularCylinder, IfcSphere))
SUBTYPE OF (IfcGeometricRepresentationItem);
Position : IfcAxis2Placement3D;
DERIVE
Dim : IfcDimensionCount := 3;
END_ENTITY;
原文：https://www.cnblogs.com/herd/p/13186240.html