8.14.3.7 IfcLightSourcePositional
8.14.3.7.1 Semantic definition
Point light node's illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is
1/max(attenuation[0] + attenuation[1] × r + attenuation[2] × r 2 , 1), where r is the distance from the light to the surface being illuminated. The default is no attenuation. An attenuation value of (0, 0, 0) is identical to (1, 0, 0). Attenuation values shall be greater than or equal to zero.
8.14.3.7.2 Entity inheritance
-
- IfcLightSource
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcPlacement
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcSurface
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
8.14.3.7.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRepresentationItem (2) | |||
| LayerAssignment | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems |
Assignment 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. |
|
| 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. |
|
| IfcLightSource (4) | |||
| 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 | AmbientIntensity | OPTIONAL 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 light. Light intensity may range from 0.0 (no light emission) to 1.0 (full intensity). |
| Click to show 6 hidden inherited attributes Click to hide 6 inherited attributes | |||
| IfcLightSourcePositional (5) | |||
| 5 | Position | IfcCartesianPoint |
Definition from ISO/CD 10303-46:1992: The Cartesian point indicates the position of the light source. Definition from VRML97 - ISO/IEC 14772-1:1997: A Point light node illuminates geometry within radius of its location. |
| 6 | Radius | IfcPositiveLengthMeasure |
The maximum distance from the light source for a surface still to be illuminated. Definition from VRML97 - ISO/IEC 14772-1:1997: A Point light node illuminates geometry within radius of its location. |
| 7 | ConstantAttenuation | IfcReal |
Definition from ISO/CD 10303-46:1992: This real indicates the value of the attenuation in the lighting equation that is constant. |
| 8 | DistanceAttenuation | IfcReal |
Definition from ISO/CD 10303-46:1992: This real indicates the value of the attenuation in the lighting equation that proportional to the distance from the light source. |
| 9 | QuadricAttenuation | IfcReal |
This real indicates the value of the attenuation in the lighting equation that proportional to the square value of the distance from the light source. |
8.14.3.7.4 Formal representation
ENTITY IfcLightSourcePositional
SUPERTYPE OF (ONEOF
(IfcLightSourceSpot))
SUBTYPE OF (IfcLightSource);
Position : IfcCartesianPoint;
Radius : IfcPositiveLengthMeasure;
ConstantAttenuation : IfcReal;
DistanceAttenuation : IfcReal;
QuadricAttenuation : IfcReal;
END_ENTITY;