Class TIfcConversionBasedUnitWithOffset

Unit

Declaration

type TIfcConversionBasedUnitWithOffset = class(TIfcConversionBasedUnit)

Description

Unit which is converted from another unit by applying a conversion factor and an offset.

Spec: https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/lexical/IfcConversionBasedUnitWithOffset.htm

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4769).

Hierarchy

Show Additional Members:

Overview

Methods

Protected function WantsGlobalId: Boolean; virtual;
Protected class function IfcClassName: String; virtual;
Public constructor Create(AOwner: TComponent); override;
Public destructor Destroy; override;

Properties

Published property GlobalId: String read FGlobalId write FGlobalId;
Published property Dimensions: TIfcDimensionalExponents read FDimensions write FDimensions;
Published property UnitType: TIfcUnitEnum read FUnitType write FUnitType default TIfcUnitEnum.UserDefined;
Published property Name: TIfcLabel read FName write FName;
Published property ConversionFactor: TIfcMeasureWithUnit read FConversionFactor write FConversionFactor;
Published property HasExternalReference: TIfcExternalReferenceRelationshipList read FHasExternalReference;
Published property ConversionOffset: TIfcReal read FConversionOffset write FConversionOffset;

Description

Methods

Protected function WantsGlobalId: Boolean; virtual;

If True, instances of this class will have GlobalId auto-assigned at saving, and they will be saved as part of the "data" list in IFC JSON files.

Strictly following the spec, this should be only defined for TIfcRoot, because only IfcRoot has GlobalId. In reality, we need GlobalId at TIfcPersistent to load some files, and we sometimes need WantsGlobalId = True to save some files.

Source: scene/load/ifc/castleifc_ifc_types.inc (line 52).

Protected class function IfcClassName: String; virtual;

Name for the IFC standard, used in IFC files. By default, this is just ClassName with prefix 'T' removed.

Source: scene/load/ifc/castleifc_ifc_types.inc (line 56).

Public constructor Create(AOwner: TComponent); override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4752).

Public destructor Destroy; override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4753).

Properties

Published property GlobalId: String read FGlobalId write FGlobalId;

Globally unique identifier for the object instance.

Note: Not declared as TGUID, because TGUID cannot be published, but also we don't really need it: for our purposes, this identifier is just an arbitrary string.

Note: IFC 4.3 specification puts this only at IfcRoot, not at every IFC class. But testcase https://github.com/buildingsmart-community/Community-Sample-Test-Files/blob/main/IFC%204.0.2.1%20(IFC%204)/ISO%20Spec%20archive/wall-with-opening-and-window.json (from IFC 4.0) shows this can be present at any IFC class, in particular TIfcGeometricRepresentationContext.

In fact, TIfcGeometricRepresentationContext needs to have GlobalId to be successfully saved (avoid recursively trying to serialize it) in some cases. We indicate such classes with WantsGlobalId.

IFC JSON documentation says this, which seems to (unfortunately it is not unambiguous enough...) allow this at any IFC class: "Whereas the globalId attribute is only available to those elements that are descendent of the IfcRoot entity in the EXPRESS schema, we encourage a broader use of this globalId, to enable referencing between objects in a JSON file when useful.".

Source: scene/load/ifc/castleifc_ifc_types.inc (line 79).

Published property Dimensions: TIfcDimensionalExponents read FDimensions write FDimensions;

Dimensional exponents of the SI base units by which the named unit is defined.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4644).

Published property UnitType: TIfcUnitEnum read FUnitType write FUnitType default TIfcUnitEnum.UserDefined;

The type of the unit.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4647).

Published property Name: TIfcLabel read FName write FName;

Word, or group of words, by which the conversion based unit is referred to.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4756).

Published property ConversionFactor: TIfcMeasureWithUnit read FConversionFactor write FConversionFactor;

The physical quantity from which the converted unit is derived.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4759).

Published property HasExternalReference: TIfcExternalReferenceRelationshipList read FHasExternalReference;

Reference to external information, e.g. library, classification, or document information, which is associated with the conversion-based unit.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4763).

Published property ConversionOffset: TIfcReal read FConversionOffset write FConversionOffset;

A positive or negative offset to add after the inherited ConversionFactor was applied.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4775).


Generated by PasDoc 0.17.0.snapshot.