Class TIfcMappedItem

Description
Hierarchy
Methods
Properties

Unit

CastleIfc

Declaration

type TIfcMappedItem = class(TIfcRepresentationItem)

Description

Inserted instance of a source definition (to be compared with a block / shared cell / macro definition). The instance is inserted by applying a Cartesian transformation operator as the MappingTarget.

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

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 2171).

Hierarchy

Show Additional Members:

Overview

Methods

Protected function WantsGlobalId: Boolean; virtual;
Protected class function IfcClassName: String; virtual;
Public function BuildNode(const Mapping: TCastleIfcMapping; const ParentProduct: TIfcProduct; const LitAppearance, UnlitAppearance: TAppearanceNode): TAbstractChildNode; virtual;
Public function BuildNode(const Mapping: TCastleIfcMapping; const ParentProduct: TIfcProduct; const LitAppearance, UnlitAppearance: TAppearanceNode): TAbstractChildNode; override;

Properties

Published property GlobalId: String read FGlobalId write FGlobalId;
Published property LayerAssignment: TIfcPresentationLayerAssignment read FLayerAssignment write FLayerAssignment;
Published property StyledByItem: TIfcStyledItem read FStyledByItem write FStyledByItem;
Published property MappingSource: TIfcRepresentationMap read FMappingSource write FMappingSource;
Published property MappingTarget: TIfcCartesianTransformationOperator read FMappingTarget write FMappingTarget;

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 function BuildNode(const Mapping: TCastleIfcMapping; const ParentProduct: TIfcProduct; const LitAppearance, UnlitAppearance: TAppearanceNode): TAbstractChildNode; virtual;

Build a node to display this using Castle Game Engine. Returns Nil if not possible / not implemented.

Parameters
ParentProduct
Parent TIfcProduct, to be used with TCastleIfcMapping.ConnectShapeAndProduct call.

It can be Nil (and TCastleIfcMapping.ConnectShapeAndProduct is already prepared to handle it too) if no particular TIfcProduct is parent of this, which (right now) only happens for some internal usage in UpdateCrossSection for throw-away shape instances.

LitAppearance
Appearance that should be used for all shapes created here, if they are supposed to be lit (made of polygons). May be given as Nil.
UnlitAppearance
Appearance that should be used for all shapes created here, if they are supposed to be unlit (made of lines, points). May be given as Nil.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 368).

Public function BuildNode(const Mapping: TCastleIfcMapping; const ParentProduct: TIfcProduct; const LitAppearance, UnlitAppearance: TAppearanceNode): TAbstractChildNode; override;

This item has no description. Showing description inherited from TIfcRepresentationItem.BuildNode.

Build a node to display this using Castle Game Engine. Returns Nil if not possible / not implemented.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 2176).

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 LayerAssignment: TIfcPresentationLayerAssignment read FLayerAssignment write FLayerAssignment;

Assignment of the representation item to a single or multiple layer(s). Nil if none.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 374).

Published property StyledByItem: TIfcStyledItem read FStyledByItem write FStyledByItem;

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. Nil if none.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 380).

Published property MappingSource: TIfcRepresentationMap read FMappingSource write FMappingSource;

A representation map that is the source of the mapped item. It can be seen as a block (or cell or marco) definition.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 2182).

Published property MappingTarget: TIfcCartesianTransformationOperator read FMappingTarget write FMappingTarget;

A representation item that is the target onto which the mapping source is mapped. It is constraint to be a Cartesian transformation operator.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 2186).

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