Class TIfcDimensionalExponents

Unit

Declaration

type TIfcDimensionalExponents = class(TIfcPersistent)

Description

The dimensionality of any quantity can be expressed as a product of powers of the dimensions of base quantities. The dimensional exponents entity defines the powers of the dimensions of the base quantities. All the physical quantities are founded on seven base quantities (ISO 31 (clause 2)).

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4582).

Hierarchy

  • TObject
  • TPersistent
  • TComponent
  • TIfcPersistent
  • TIfcDimensionalExponents
Show Additional Members:

Overview

Methods

Protected function WantsGlobalId: Boolean; virtual;
Protected class function IfcClassName: String; virtual;

Properties

Published property GlobalId: String read FGlobalId write FGlobalId;
Published property LengthExponent: Integer read FLengthExponent write FLengthExponent default 0;
Published property MassExponent: Integer read FMassExponent write FMassExponent default 0;
Published property TimeExponent: Integer read FTimeExponent write FTimeExponent default 0;
Published property ElectricCurrentExponent: Integer read FElectricCurrentExponent write FElectricCurrentExponent default 0;
Published property ThermodynamicTemperatureExponent: Integer read FThermodynamicTemperatureExponent write FThermodynamicTemperatureExponent default 0;
Published property AmountOfSubstanceExponent: Integer read FAmountOfSubstanceExponent write FAmountOfSubstanceExponent default 0;
Published property LuminousIntensityExponent: Integer read FLuminousIntensityExponent write FLuminousIntensityExponent default 0;

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).

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 LengthExponent: Integer read FLengthExponent write FLengthExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4592).

Published property MassExponent: Integer read FMassExponent write FMassExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4593).

Published property TimeExponent: Integer read FTimeExponent write FTimeExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4594).

Published property ElectricCurrentExponent: Integer read FElectricCurrentExponent write FElectricCurrentExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4595).

Published property ThermodynamicTemperatureExponent: Integer read FThermodynamicTemperatureExponent write FThermodynamicTemperatureExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4596).

Published property AmountOfSubstanceExponent: Integer read FAmountOfSubstanceExponent write FAmountOfSubstanceExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4597).

Published property LuminousIntensityExponent: Integer read FLuminousIntensityExponent write FLuminousIntensityExponent default 0;

This item has no description.

Source: scene/load/ifc/castleifc_ifc_standard_types.inc (line 4598).


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