IfcConic是参数化的平面曲线。
注：定义根据ISO/CD 10303-42:1992
圆锥曲线是一个平面曲线，它可以由一个平面与一个圆锥相交而成。圆锥曲线是根据其固有的几何性质来定义的，而不是用其他几何来描述的。圆锥实体始终有一个由axis2_placement定义的放置坐标系；参数表示是根据该放置坐标系定义的。
注：实体改编自ISO 10303-42中定义的圆锥曲线
IFC1.0中增加的新实体
| # | 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 | |||||
| IfcCurve | |||||
| Dim :=IfcCurveDim(SELF) |
IfcDimensionCount | [1:1] | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | X | |
| IfcConic | |||||
| 1 | Position | IfcAxis2Placement | [1:1] | The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes." | X |
EXPRESS Specification
ENTITY IfcConic
ABSTRACT SUPERTYPE OF(ONEOF(IfcCircle, IfcEllipse))
SUBTYPE OF (IfcCurve);
Position : IfcAxis2Placement;
END_ENTITY;
原文：https://www.cnblogs.com/herd/p/13268313.html