IfcIndexedColourMap

Item	SPF	XML	Change	Description
IFC2x3 to IFC4
IfcIndexedColourMap			ADDED
IFC4 Addendum 1
IfcIndexedColourMap
Opacity	X	X	MODIFIED	Name changed from Overrides to Opacity. Type changed from IfcSurfaceStyleShading to IfcNormalisedRatioMeasure.
ColourIndex			MODIFIED	Type changed from INTEGER to IfcPositiveInteger.

Semantic definitions at the entity

Entity definition

The IfcIndexedColourMap provides the assignment of colour information to individual faces. It is used for colouring faces of tessellated face sets. The IfcIndexedColourMap defines an index into an indexed list of colour information. The Colours are a two-dimensional list of colours provided by three RGB values. The ColourIndex attribute corresponds to the CoordIndex of the IfcTessellatedFaceSet defining the corresponding index list of faces. The Opacity attribute provides the alpha channel for all faces of the tessellated face set.

Figure 363 shows the use of IfcTriangulatedFaceSet with colours per face.


Figure 363 — Indexed colour map

Figure 364 illustrates an IfcTriangulatedFaceSet represented by

IfcTriangulatedFaceSet.CoordIndex: ((1,6,5),(1,2,6), (6,2,7), (7,2,3), (7,8,6), (6,8,5), (5,8,1), (1,8,4), (4,2,1), (2,4,3), (4,8,7), (7,3,4))
IfcCartesianPointList.CoordList: ((0.,0.,0.), (1.,0.,0.), (1.,1.,0.), (0.,1.,0.), (0.,0.,2.), (1.,0.,2.), (1.,1.,2.), (0.,1.,2.))
IfcIndexedColourMap.ColourIndex: (1, 1, 2, 2, 3, 3, 1, 1, 1, 1, 1, 1, )
IfcColourRgbList.ColourList: ((1.,0.,0.), (0.,1.,0.), (1.,1.,0.))

Figure 364 — Indexed colour map geometry

HISTORY New entity in IFC4.

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
1	MappedTo	IfcTessellatedFaceSet	[1:1]	Reference to the IfcTessellatedFaceSet to which it applies the colours and alpha channel.	X
2	Opacity	IfcNormalisedRatioMeasure	[0:1]	The the opacity value, that applies equaly to all faces of the tessellated face set. 1.0 means opaque, and 0.0 completely transparent. If not provided, 1.0 is assumed (all colours are opque). NOTE The definition of the alpha channel component for opacity follows the new definitions in image processing, where 0.0 means full transparency and 1.0 (or 2^{bit depths} -1) means fully opaque. This is contrary to the definition of transparency in IfcSurfaceStyleShading.	X
3	Colours	IfcColourRgbList	[1:1]	Indexable list of lists of quadruples, representing RGB colours.	X
4	ColourIndex	IfcPositiveInteger	L[1:?]	Index into the IfcColourRgbList for each face of the IfcTriangulatedFaceSet. The colour is applied uniformly to the indexed face.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPresentationItem
IfcIndexedColourMap
1	MappedTo	IfcTessellatedFaceSet	[1:1]	Reference to the IfcTessellatedFaceSet to which it applies the colours and alpha channel.	X
2	Opacity	IfcNormalisedRatioMeasure	[0:1]	The the opacity value, that applies equaly to all faces of the tessellated face set. 1.0 means opaque, and 0.0 completely transparent. If not provided, 1.0 is assumed (all colours are opque). NOTE The definition of the alpha channel component for opacity follows the new definitions in image processing, where 0.0 means full transparency and 1.0 (or 2^{bit depths} -1) means fully opaque. This is contrary to the definition of transparency in IfcSurfaceStyleShading.	X
3	Colours	IfcColourRgbList	[1:1]	Indexable list of lists of quadruples, representing RGB colours.	X
4	ColourIndex	IfcPositiveInteger	L[1:?]	Index into the IfcColourRgbList for each face of the IfcTriangulatedFaceSet. The colour is applied uniformly to the indexed face.	X

Formal representations

XSD Specification

 <xs:element name="IfcIndexedColourMap" type="ifc:IfcIndexedColourMap" substitutionGroup="ifc:IfcPresentationItem" nillable="true"/>

 <xs:complexType name="IfcIndexedColourMap">

  <xs:complexContent>

   <xs:extension base="ifc:IfcPresentationItem">

    <xs:sequence>

     <xs:element name="Colours" type="ifc:IfcColourRgbList" nillable="true"/>

    </xs:sequence>

    <xs:attribute name="Opacity" type="ifc:IfcNormalisedRatioMeasure" use="optional"/>

    <xs:attribute name="ColourIndex" use="optional">

     <xs:simpleType>

      <xs:restriction>

       <xs:simpleType>

        <xs:list itemType="ifc:IfcPositiveInteger"/>

       </xs:simpleType>

      </xs:restriction>

     </xs:simpleType>

    </xs:attribute>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcIndexedColourMap

 SUBTYPE OF (IfcPresentationItem);

  MappedTo : IfcTessellatedFaceSet;

  Opacity : OPTIONAL IfcNormalisedRatioMeasure;

  Colours : IfcColourRgbList;

  ColourIndex : LIST [1:?] OF IfcPositiveInteger;

END_ENTITY;

 EXPRESS-G diagram

	Liste von Indizes für Farbwerte
	Indexed Colour Map

IfcIndexedColourMap

Semantic definitions at the entity

Inherited definitions from supertypes

Examples

Formal representations