IfcTextureMap

Item	SPF	XML	Change	Description
IFC2x3 to IFC4
IfcTextureMap			MOVED	Schema changed from IFCPRESENTATIONDEFINITIONRESOURCE to IFCPRESENTATIONAPPEARANCERESOURCE.
Maps	X	X	MODIFIED	Name changed from TextureMaps to Maps. Type changed from IfcVertexBasedTextureMap to IfcSurfaceTexture. Aggregation changed from SET to LIST.
Vertices			ADDED
MappedTo			ADDED

Semantic definitions at the entity

Entity definition

An IfcTextureMap provides the mapping of the 2-dimensional texture coordinates to the surface onto which it is mapped. It is used for mapping the texture to surfaces of vertex based geometry models, such as

The IfcTextureMap has a list of TextureVertex, that corresponds to the points of the outer face bound of the vertex based geometry item. The corresponding pair of lists is:

the list of Polygon of the IfcFaceOuterBound of type IfcCartesianPoint, and
the list of Vertices of type IfcTextureVertex.

Each IfcTextureVertex (given as S, T coordinates of the 2-dimension texture coordinate system) corresponds to the geometric coordinates of the IfcCartesianPoint (given as 3-dimension X, Y, and Z coordinates within the object coordinate system of the geometric item).

NOTE Definition according to ISO/IEC 19775-1:
The TextureCoordinate node is a geometry property node that specifies a set of 2D texture coordinates used by vertex-based geometry nodes to map textures to vertices.

NOTE In contrary to the X3D vertext based geometry, for example IndexedFaceSet and ElevationGrid, the vertext based geometry in IFC may include inner loops. The areas of inner loops have to be cut-out from the texture applied to the outer loop.

	Figure 369 illustrates applying a texture map to a vertex based geometry.
Figure 369 — Texture map

HISTORY New entity in IFC2x2.

IFC2x3 CHANGE The attribute Texture is deleted, and the attribute TextureMaps is added.

IFC4 CHANGE The attribute TextureMap is replaced by Vertices, and the attribute AppliedTo is added.

Informal Propositions:

The IfcFace referenced in AppliedTo shall be used by the vertex based geometry, to which this texture map is assigned to by through the IfcStyledItem.

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
2	Vertices	IfcTextureVertex	L[3:?]	List of texture coordinate vertices that are applied to the corresponding points of the polyloop defining a face bound.	X
3	MappedTo	IfcFace	[1:1]	The face that defines the corresponding list of points along the bounding poly loop of the face outer bound. NOTE The face may have additional inner loops. The IfcTextureMap and its Vertices only correspond with the coordinates of the IfcPolyloop representing the outer bound.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPresentationItem
IfcTextureCoordinate
1	Maps	IfcSurfaceTexture	L[1:?]	Reference to the one (or many in case of multi textures with identity transformation to geometric surfaces) subtype(s) of IfcSurfaceTexture that are mapped to a geometric surface by the texture coordinate transformation.	X
IfcTextureMap
2	Vertices	IfcTextureVertex	L[3:?]	List of texture coordinate vertices that are applied to the corresponding points of the polyloop defining a face bound.	X
3	MappedTo	IfcFace	[1:1]	The face that defines the corresponding list of points along the bounding poly loop of the face outer bound. NOTE The face may have additional inner loops. The IfcTextureMap and its Vertices only correspond with the coordinates of the IfcPolyloop representing the outer bound.	X

Formal representations

XSD Specification

 <xs:element name="IfcTextureMap" type="ifc:IfcTextureMap" substitutionGroup="ifc:IfcTextureCoordinate" nillable="true"/>

 <xs:complexType name="IfcTextureMap">

  <xs:complexContent>

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

    <xs:sequence>

     <xs:element name="Vertices">

      <xs:complexType>

       <xs:sequence>

        <xs:element ref="ifc:IfcTextureVertex" minOccurs="3" maxOccurs="unbounded"/>

       </xs:sequence>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcTextureVertex"/>

       <xs:attribute ref="ifc:cType" fixed="list"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

     <xs:element name="MappedTo" type="ifc:IfcFace" nillable="true"/>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcTextureMap

 SUBTYPE OF (IfcTextureCoordinate);

  Vertices : LIST [3:?] OF IfcTextureVertex;

  MappedTo : IfcFace;

END_ENTITY;

 EXPRESS-G diagram

	Texturmapping
	Texture Map
	Image de texture