IFC 4.3.x development

8.15.3.26 IfcTrapeziumProfileDef

8.15.3.26.1 Semantic definitions at the entity

IfcTrapeziumProfileDef defines a trapezium as the profile definition used by the swept surface geometry or the swept area solid. It is given by its Top X and Bottom X extent and its Y extent as well as by the offset of the Top X extend, and placed within the 2D position coordinate system, established by the Position attribute. It is placed centric within the position coordinate system, that is, in the center of the bounding box.

HISTORY  New entity in IFC1.5. The use definition has changed in IFC2x.

Figure 1 illustrates parameters of the trapezium profile definition.

trapezium profile Position
The parameterized profile defines its own position coordinate system. The underlying coordinate system is defined by the swept surface or swept area solid that uses the profile definition. It is the xy plane of either: or in case of sectioned spines the xy plane of each list member of IfcSectionedSpine.CrossSectionPositions.

By using offsets of the position location, the parameterized profile can be positioned centric (using x,y offsets = 0.), or at any position relative to the profile. Explicit coordinate offsets are used to define cardinal points (e.g. upper-left bound).

Parameter
The IfcTrapeziumProfileDef is defined within the position coordinate system, where the BottomDim defines the length measure for the bottom line (half along the positive x-axis) and the YDim defines the length measure for the parallel distance of bottom and top line (half along the positive y-axis). The top line starts with a distance of TopXOffset from [-BottomLine/2,YDim] (which can be negative, zero, or positive) and has a length of TopXDim along the positive x-axis.

Figure 1 — Trapezium profile

8.15.3.26.1 Attributes

# Attribute Type Description
IfcProfileDef
1 ProfileType IfcProfileTypeEnum Defines the type of geometry into which this profile definition shall be resolved, either a curve or a surface area. In case of curve the profile should be referenced by a swept surface, in case of area the profile should be referenced by a swept area solid.
2 ProfileName OPTIONAL IfcLabel Human-readable name of the profile, for example according to a standard profile table. As noted above, machine-readable standardized profile designations should be provided in _IfcExternalReference.ItemReference_.
HasExternalReferenceSET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjectsReference to external information, e.g. library, classification, or document information, which is associated with the profile.

> IFC4 CHANGE New inverse attribute

HasProperties SET [0:?] OF IfcProfileProperties FOR ProfileDefinition Additional properties of the profile, for example mechanical properties.

> IFC4 CHANGE New inverse attribute

IfcParameterizedProfileDef
3 Position OPTIONAL IfcAxis2Placement2D Position coordinate system of the parameterized profile definition. If unspecified, no translation and no rotation is applied.
IfcTrapeziumProfileDef
4 BottomXDim IfcPositiveLengthMeasure The extent of the bottom line measured along the implicit x-axis.
5 TopXDim IfcPositiveLengthMeasure The extent of the top line measured along the implicit x-axis.
6 YDim IfcPositiveLengthMeasure The extent of the distance between the parallel bottom and top lines measured along the implicit y-axis.
7 TopXOffset IfcLengthMeasure Offset from the beginning of the top line to the bottom line, measured along the implicit x-axis.

8.15.3.26.2 Entity inheritance

dot_inheritance IfcTrapeziumProfileDef IfcTrapeziumProfileDef IfcParameterizedProfileDef IfcParameterizedProfileDef IfcTrapeziumProfileDef->IfcParameterizedProfileDef IfcParameterizedProfileDef_children 10 more... IfcParameterizedProfileDef_children->IfcParameterizedProfileDef IfcProfileDef IfcProfileDef IfcParameterizedProfileDef->IfcProfileDef IfcProfileDef_children 5 more... IfcProfileDef_children->IfcProfileDef

8.15.3.26.3 Definitions applying to General Usage

8.15.3.26.3.1 Property Sets for Objects

PsetName
'Pset_ProfileMechanical'

8.15.3.26.4 Formal representations

ENTITY IfcTrapeziumProfileDef
 SUBTYPE OF (IfcParameterizedProfileDef);
	BottomXDim : IfcPositiveLengthMeasure;
	TopXDim : IfcPositiveLengthMeasure;
	YDim : IfcPositiveLengthMeasure;
	TopXOffset : IfcLengthMeasure;
END_ENTITY;