IFC 4.3.x development

8.8.3.23 IfcIndexedPolygonalFace

Change log

IFC4

added

8.8.3.23.1 Semantic definitions at the entity

The IfcIndexedPolygonalFace is a compact representation of a planar face being part of a face set. The vertices of the polygonal planar face are provided by 3 or more Cartesian points, defined by indices that point into an IfcCartesianPointList3D, either direcly, or via the PnIndex, if provided at IfcPolygonalFaceSet.

Figure 1 shows an IfcIndexedPolygonalFace at an IfcPolygonalFaceSet not using PnIndex (the default).

"<a href=IfcIndexedPolygonalFace"' src="../figures/ifcindexedpolygonalface_01.png" title="Figure 1 — Polygonal face geometry provided by indices into a point list"/>

 

Figure 2 shows an IfcIndexedPolygonalFace at an IfcPolygonalFaceSet using PnIndex.

"<a href=IfcIndexedPolygonalFace us ing PnIndex"' src="../figures/ifcindexedpolygonalface_02.png" title="Figure 2 — Polygonal face geometry provided by indices into a point list"/>

HISTORY  New entity in IFC4 Addendum 2.

8.8.3.23.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignmentSET [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
IfcTessellatedItem
IfcIndexedPolygonalFace
1 CoordIndex LIST [3:?] OF IfcPositiveInteger One-dimensional list with the indices for the three or more points, that define the vertices of the outer loop. If the tessellated face set is closed, indicated by _SELF\IfcTessellatedFaceSet.Closed_, then the points, defining the outer loop, shall connect counter clockwise, as seen from the outside of the body, so that the resulting normal will point outwards.

> NOTE  The coordinates of the vertices are provided by the indexed list of _SELF\IfcTessellatedFaceSet.Coordinates.CoordList_. If the _SELF\IfcTessellatedFaceSet.PnIndex_ is provided, the indices point into it, otherwise directly into the IfcCartesianPointList3D.
ToFaceSet SET [1:?] OF IfcPolygonalFaceSet FOR Faces Reference to the IfcPolygonalFaceSet for which this face is associated.

8.8.3.23.2 Entity inheritance

dot_inheritance IfcIndexedPolygonalFaceWithVoids IfcIndexedPolygonalFaceWithVoids IfcIndexedPolygonalFace IfcIndexedPolygonalFace IfcIndexedPolygonalFaceWithVoids->IfcIndexedPolygonalFace IfcTessellatedItem IfcTessellatedItem IfcIndexedPolygonalFace->IfcTessellatedItem IfcTessellatedFaceSet IfcTessellatedFaceSet IfcTessellatedFaceSet->IfcTessellatedItem IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcTessellatedItem->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.8.3.23.3 Formal representations

ENTITY IfcIndexedPolygonalFace
 SUPERTYPE OF (ONEOF
	(IfcIndexedPolygonalFaceWithVoids))
 SUBTYPE OF (IfcTessellatedItem);
	CoordIndex : LIST [3:?] OF IfcPositiveInteger;
 INVERSE
	ToFaceSet : SET [1:?] OF IfcPolygonalFaceSet FOR Faces;
END_ENTITY;