IfcCurveStyle为指定给几何曲线的表示信息提供样式表。样式由颜色、字体和宽度定义。IfcCurveStyle将曲线填充图案定义为模型填充图案，也就是说，曲线填充图案的可见段和不可见段之间的距离以模型空间标注的形式给出（必须使用目标打印比例进行缩放）。

样式将由多个IfcStyledItem共享，将样式指定给IfcGeometricRepresentationItem的（子类型）。字体样式或曲线宽度的度量值以全局图形长度单位表示。

注意全局单位是在单个IfcProject实例中定义的，由单位给出InContext:IfcUnitAssignment文件，相同的单位用于几何表示项和样式定义。

字体样式和曲线宽度的度量值应用于模型空间，并提供了目标打印比例，以确保在默认打印比例下的正确外观。。对于不同的比例和投影相关曲线样式，IfcPresentationStyleAssignment需要使用不同的IfcCurveStyle实例来指定不同的IfcGeometricPresentationSubContext相关表示。

注：目标标度由IfcGeometricRepr给出演示SubContext.TargetScale.

IfcCurveStyle可以通过中间IfcStyledItem或IfcOntationCurveOccurrence的IfcPresentationStyleAssignment分配给IfcGeometricPresentationItem。

注：定义符合ISO/CD 10303-46:1992

曲线样式指定曲线的视觉外观。

注：对应ISO 10303名称：曲线样式。正式标准的最终定义请参考ISO/IS 10303-46:1994。

IFC2x2中增加的新实体。

 

ormal Propositions

Rule	Description
MeasureOfWidth	如果提供了曲线宽度，则应通过以默认测量单位表示曲线宽度的IfcPositiveLengthMeasure给出，或通过IfcDescriptiveMeasure给出，其值“按层”表示相关层处以默认曲线宽度表示的曲线宽度。
IdentifiableCurveStyle	至少必须提供三个属性值中的一个：CurveFont、CurveWidth、CurveColour。

 

 

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPresentationStyle
1	Name	IfcLabel	[0:1]	Name of the presentation style.	X
IfcCurveStyle
2	CurveFont	IfcCurveFontOrScaledCurveFontSelect	[0:1]	A curve style font which is used to present a curve. It can either be a predefined curve font, or an explicitly defined curve font. Both may be scaled. If not given, then the curve font should be taken from the layer assignment with style, if that is not given either, then the default curve font applies.	X
3	CurveWidth	IfcSizeSelect	[0:1]	A positive length measure in units of the presentation area for the width of a presented curve. If not given, then the style should be taken from the layer assignment with style, if that is not given either, then the default style applies.	X
4	CurveColour	IfcColour	[0:1]	The colour of the visible part of the curve. If not given, then the colour should be taken from the layer assignment with style, if that is not given either, then the default colour applies.	X
5	ModelOrDraughting	IfcBoolean	[0:1]	Indication whether the length measures provided for the presentation style are model based, or draughting based.	X

 

 

EXPRESS Specification

ENTITY IfcCurveStyle
 SUBTYPE OF (IfcPresentationStyle);
  CurveFont : OPTIONAL IfcCurveFontOrScaledCurveFontSelect;
  CurveWidth : OPTIONAL IfcSizeSelect;
  CurveColour : OPTIONAL IfcColour;
  ModelOrDraughting : OPTIONAL IfcBoolean;
 WHERE
  MeasureOfWidth : (NOT(EXISTS(CurveWidth))) OR ('IFCMEASURERESOURCE.IFCPOSITIVELENGTHMEASURE' IN TYPEOF(CurveWidth)) OR (('IFCMEASURERESOURCE.IFCDESCRIPTIVEMEASURE' IN TYPEOF(CurveWidth)) AND (CurveWidth = 'by layer'));
  IdentifiableCurveStyle : EXISTS(CurveFont) OR EXISTS(CurveWidth) OR EXISTS(CurveColour);
END_ENTITY;