Class TIfcTrimmedCurve

Description
Hierarchy
Methods
Properties

Unit

CastleIfc

Declaration

type TIfcTrimmedCurve = class(TIfcBoundedCurve)

Description

Bounded curve that is trimmed at both ends.

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

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 958).

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 procedure UpdateCrossSection(const CrossSection: TVector2List; var CrossSectionConvex: Boolean); virtual;
Public constructor Create(AOwner: TComponent); override;
Public destructor Destroy; override;
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 BasisCurve: TIfcCurve read FBasisCurve write FBasisCurve;
Published property Trim1: TIfcCartesianPointList read FTrim1;
Published property Trim2: TIfcCartesianPointList read FTrim2;
Published property SenseAgreement: Boolean read FSenseAgreement write FSenseAgreement default false;
Published property MasterRepresentation: TIfcTrimmingPreference read FMasterRepresentation write FMasterRepresentation default TIfcTrimmingPreference.Unspecified;

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 procedure UpdateCrossSection(const CrossSection: TVector2List; var CrossSectionConvex: Boolean); virtual;

Update CrossSection to be used by IfcExtrudedAreaSolid. In the base class, this reuses BuildNode and extracts cross section information from a temporary node. Override to provide more optimized implementation.

Set CrossSectionConvex to False if the cross-section is potentially concave. By default we assume faster True, so convex.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 934).

Public constructor Create(AOwner: TComponent); override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 966).

Public destructor Destroy; override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 967).

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 968).

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 BasisCurve: TIfcCurve read FBasisCurve write FBasisCurve;

The curve to be trimmed. For curves with multiple representations any parameter values given as Trim1 or Trim2 refer to the master representation of the BasisCurve only.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 975).

Published property Trim1: TIfcCartesianPointList read FTrim1;

The first trimming point. TODO: We support only TIfcCartesianPoint, but IFC spec allows more, IfcTrimmingSelect.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 980).

Published property Trim2: TIfcCartesianPointList read FTrim2;

The second trimming point. TODO: We support only TIfcCartesianPoint, but IFC spec allows more, IfcTrimmingSelect.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 985).

Published property SenseAgreement: Boolean read FSenseAgreement write FSenseAgreement default false;

Flag to indicate whether the direction of the trimmed curve agrees with or is opposed to the direction of the basis curve.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 989).

Published property MasterRepresentation: TIfcTrimmingPreference read FMasterRepresentation write FMasterRepresentation default TIfcTrimmingPreference.Unspecified;

Where both parameter and point are present at either end of the curve this indicates the preferred form.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 994).

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