Class TIfcTextureVertexList_Spec

Unit

Declaration

type TIfcTextureVertexList_Spec = class(TIfcPresentationItem)

Description

Ordered collection of 2D texture coordinates.

Name in Pascal is with "_Spec" suffix to clarify this is "specification defined list-like class" and not just TObjectList<TIfcTextureVertexList>.

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

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 723).

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 TexCoordsList: TVector2List read FTexCoordsList;

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 727).

Public destructor Destroy; override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 728).

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 TexCoordsList: TVector2List read FTexCoordsList;

List of texture vertices defined by S-coordinate and T-coordinate.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 731).


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