8.8.3.45 IfcTessellatedFaceSet

RV ⓘ

AbV ⓘ

ABSTRACT This definition may not be instantiated

8.8.3.45.1 Semantic definition

The IfcTessellatedFaceSet is a boundary representation topological model limited to planar faces and straight edges. It may represent an approximation of an analytical surface or solid that may be provided in addition to its tessellation as a separate shape representation. The IfcTessellatedFaceSet provides a compact data representation of an connected face set using indices into ordered lists of vertices, normals, colours, and texture maps.

The IfcTessellatedFaceSet is an abstract supertype of tessellated face sets each imposing specific constraints on face generation for tessellation, such as triangulation (with or without strip and fans), or quadrilaterals, or polygonal faces (with or without inner loops).

The following attributes apply to all subtypes:

The Coordinates are the ordered list of Cartesian points representing the vertices of the tessellated item. An index list, defined at the level of subtypes, uses the points, identified by index position, to construct the polylines that represent the faces.
The HasColours inverse relation provides an indexed colour map with an corresponding list of indices providing a colour for each face of the tessellated face set.
The HasTextures inverse relation provides an indexed texture map with an corresponding list of indices providing texture coordinates that map to the geometric coordinates of the polylines representing the faces.

Each face of the tessellated face set shall have:

at least three non-coincident vertices;
vertices that define a planar polygon;
vertices that define a non-self-intersecting polygon.

8.8.3.45.2 Entity inheritance

8.8.3.45.3 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. 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.
Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcTessellatedFaceSet (4)
1	Coordinates	IfcCartesianPointList3D	An ordered list of Cartesian points used by the coordinate index defined at the subtypes of IfcTessellatedFaceSet.
	HasColours	SET [0:1] OF IfcIndexedColourMap FOR MappedTo	Reference to the indexed colour map providing the corresponding colour RGB values to the faces of the subtypes of IfcTessellatedFaceSet.
	HasTextures	SET [0:?] OF IfcIndexedTextureMap FOR MappedTo	Reference to the indexed texture map providing the corresponding texture coordinates to the vertices bounding the faces of the subtypes of IfcTessellatedFaceSet.
*	Dim	IfcDimensionCount	This attribute is formally derived. `3` The space dimensionality of this geometric representation item, it is always 3.

Table 8.8.3.45.A

8.8.3.45.4 Formal representation

ENTITY IfcTessellatedFaceSet
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcPolygonalFaceSet
	,IfcTriangulatedFaceSet))
 SUBTYPE OF (IfcTessellatedItem);
	Coordinates : IfcCartesianPointList3D;
 DERIVE
	 Dim : IfcDimensionCount := 3;
 INVERSE
	HasColours : SET [0:1] OF IfcIndexedColourMap FOR MappedTo;
	HasTextures : SET [0:?] OF IfcIndexedTextureMap FOR MappedTo;
END_ENTITY;