#### 8.10.3.3 IfcCurveStyle

| Style de courbe
| Linienstil

An IfcCurveStyle provides the style table for presentation information assigned to geometric curves. The style is defined by a color, a font and a width. The IfcCurveStyle defines curve patterns as model patterns, that is, the distance between visible and invisible segments of curve patterns are given in model space dimensions (that have to be scaled using the target plot scale).

Styles are intended to be shared by multiple IfcStyledItem's, assigning the style to occurrences of (subtypes of) IfcGeometricRepresentationItem's. Measures given to a font pattern or a curve width are given in global drawing length units.

> NOTE global units are defined at the single IfcProject instance, given by UnitsInContext:IfcUnitAssignment, the same units are used for the geometric representation items and for the style definitions.

The measure values for font pattern and curve width apply to the model space with a target plot scale provided for the correct appearance in the default plot scale.. For different scale and projection dependent curve styles a different instance of IfcCurveStyle needs to be used by IfcPresentationStyleAssignment for different IfcGeometricRepresentationSubContext dependent representations.

> NOTE the target plot scale is given by IfcGeometricRepresentationSubContext.TargetScale.

An IfcCurveStyle can be assigned to IfcGeometricRepresentationItem's via the IfcPresentationStyleAssignment through an intermediate IfcStyledItem or IfcAnnotationCurveOccurrence.

> NOTE Definition according to ISO/CD 10303-46:1992
> A curve style specifies the visual appearance of curves.

> NOTE Corresponding ISO 10303 name: curve_style. Please refer to ISO/IS 10303-46:1994 for the final definition of the formal standard.

> HISTORY New entity in IFC2x2.

XSD Specification:

<xs:element name="IfcCurveStyle" type="ifc:IfcCurveStyle" substitutionGroup="ifc:IfcPresentationStyle" nillable="true"/>
<xs:complexType name="IfcCurveStyle">
<xs:complexContent>
<xs:extension base="ifc:IfcPresentationStyle"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcCurveStyle

| SUBTYPE OF (IfcPresentationStyle);

CurveFont | : | OPTIONAL IfcStrippedOptional;
CurveWidth | : | OPTIONAL IfcStrippedOptional;
CurveColour | : | OPTIONAL IfcStrippedOptional;
ModelOrDraughting | : | OPTIONAL IfcStrippedOptional;

| 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;

Attribute Definitions:

ModelOrDraughting | : | Indication whether the length measures provided for the presentation style are model based, or draughting based. IFC4 CHANGE New attribute.

Formal Propositions:

MeasureOfWidth | : | The curve width, if provided, shall be given by an IfcPositiveLengthMeasure representing the curve width in the default measure unit, or by an IfcDescriptiveMeasure with the value 'by layer' representing the curve width by the default curve width at the associated layer.
IdentifiableCurveStyle | : | At minimum one of the three attribute values have to be provided, CurveFont, CurveWidth, CurveColour.

Inheritance Graph:

ENTITY IfcCurveStyle

| ENTITY IfcPresentationStyle

Name | : | OPTIONAL IfcStrippedOptional;

| ENTITY IfcCurveStyle

CurveFont | : | OPTIONAL IfcStrippedOptional;
CurveWidth | : | OPTIONAL IfcStrippedOptional;
CurveColour | : | OPTIONAL IfcStrippedOptional;
ModelOrDraughting | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

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