Class TIfcPolyline

Unit

Declaration

type TIfcPolyline = class(TIfcBoundedCurve)

Description

Bounded curve with only linear segments defined by a list of Cartesian points. If the first and the last Cartesian point in the list are identical, then the polyline is a closed curve, otherwise it is an open curve.

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

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1004).

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;
Public function BuildNode(const Mapping: TCastleIfcMapping; const ParentProduct: TIfcProduct; const LitAppearance, UnlitAppearance: TAppearanceNode): TAbstractChildNode; override;
Public procedure UpdateCrossSection(const CrossSection: TVector2List; var CrossSectionConvex: Boolean); 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 Points: TIfcCartesianPointList read FPoints;

Description

Methods

Protected function WantsGlobalId: Boolean; virtual;

This item is declared in ancestor TIfcPersistent.

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;

This item is declared in ancestor TIfcPersistent.

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 1008).

Public destructor Destroy; override;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1009).

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 1010).

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

This item has no description. Showing description inherited from TIfcCurve.UpdateCrossSection.

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 1013).

Properties

Published property GlobalId: String read FGlobalId write FGlobalId;

This item is declared in ancestor TIfcPersistent.

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;

This item is declared in ancestor TIfcRepresentationItem.

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;

This item is declared in ancestor TIfcRepresentationItem.

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 Points: TIfcCartesianPointList read FPoints;

Points defining the polyline.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 1017).


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