Class TIfcRelVoidsElement

Description

Hierarchy

Methods

Properties

Unit

CastleIfc

Declaration

type TIfcRelVoidsElement = class(TIfcRoot)

Description

Relationship between a building element and one opening element that creates a void in the element. It is a one-to-one relationship. This relationship implies a boolean operation of subtraction between the geometric bodies of the element and the opening.

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

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4308).

Hierarchy

TObject
TPersistent
TComponent
TIfcPersistent
TIfcRoot
TIfcRelVoidsElement

Show Additional Members: Inherited Protected

Overview

Methods

Protected	`function WantsGlobalId: Boolean; virtual;`
Protected	`class function IfcClassName: String; virtual;`
Protected	`function WantsGlobalId: Boolean; override;`
Public	`function BuildNode(const Mapping: TCastleIfcMapping): TAbstractChildNode;`

Properties

Published	`property GlobalId: String read FGlobalId write FGlobalId;`
Published	`property OwnerHistory: TIfcOwnerHistory read FOwnerHistory write FOwnerHistory;`
Published	`property Name: TIfcLabel read FName write FName;`
Published	`property Description: TIfcText read FDescription write FDescription;`
Published	`property RelatingBuildingElement: TIfcElement read FRelatingBuildingElement write FRelatingBuildingElement;`
Published	`property RelatedOpeningElement: TIfcFeatureElementSubtraction read FRelatedOpeningElement write FRelatedOpeningElement;`

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).

Protected function WantsGlobalId: Boolean; override;

This item has no description. Showing description inherited from TIfcPersistent.WantsGlobalId.

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.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1656).

Public function BuildNode(const Mapping: TCastleIfcMapping): TAbstractChildNode;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4313).

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 OwnerHistory: TIfcOwnerHistory read FOwnerHistory write FOwnerHistory;

Information about the current ownership of that object.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1659).

Published property Name: TIfcLabel read FName write FName;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1661).

Published property Description: TIfcText read FDescription write FDescription;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1662).

Published property RelatingBuildingElement: TIfcElement read FRelatingBuildingElement write FRelatingBuildingElement;

This item has no description.