IFC 4.3.x development

8.14.3.3 IfcLightSource

8.14.3.3.1 Semantic definitions at the entity

NOTE  Definition according to ISO 10303-46:
The light source entity is determined by the reflectance specified in the surface style rendering. Lighting is applied on a surface by surface basis: no interactions between surfaces such as shadows or reflections are defined.

NOTE  Entity adapted from light_source defined in ISO 10303-46.

NOTE  In addition to the attributes as defined in ISO10303-46 the following additional properties from ISO/IEC 14772-1:1997 (VRML) are added: ambientIntensity and Intensity. The attribute Name has been added as well (as it is not inherited via representation_item).

HISTORY  New entity in IFC2x, renamed and enhanced in IFC2x2.

8.14.3.3.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.



> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
IfcGeometricRepresentationItem
IfcLightSource
1 Name OPTIONAL IfcLabel The name given to the light source in presentation.
2 LightColour IfcColourRgb Definition from ISO/CD 10303-46:1992: Based on the current lighting model, the colour of the light to be used for shading.

Definition from VRML97 - ISO/IEC 14772-1:1997: The color field specifies the spectral color properties of both the direct and ambient light emission as an RGB value.
3 AmbientIntensityOPTIONAL IfcNormalisedRatioMeasure Definition from VRML97 - ISO/IEC 14772-1:1997: The ambientIntensity specifies the intensity of the ambient emission from the light. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity).
4 Intensity OPTIONAL IfcNormalisedRatioMeasure Definition from VRML97 - ISO/IEC 14772-1:1997: The intensity field specifies the brightness of the direct emission from the ligth. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity).

8.14.3.3.2 Entity inheritance

dot_inheritance IfcLightSource_children 3 more... IfcLightSource IfcLightSource IfcLightSource_children->IfcLightSource IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcLightSource->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.14.3.3.3 Formal representations

ENTITY IfcLightSource
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcLightSourceAmbient
	,IfcLightSourceDirectional
	,IfcLightSourceGoniometric
	,IfcLightSourcePositional))
 SUBTYPE OF (IfcGeometricRepresentationItem);
	Name : OPTIONAL IfcLabel;
	LightColour : IfcColourRgb;
	AmbientIntensity : OPTIONAL IfcNormalisedRatioMeasure;
	Intensity : OPTIONAL IfcNormalisedRatioMeasure;
END_ENTITY;