8.20.3.6 IfcEdgeLoop
8.20.3.6.1 Semantic definition
Informal Propositions
- The genus of the IfcEdgeLoop shall be 1 or greater.
- The Euler formula shall be satisfied: (number of vertices) + genus - (number of edges) = 1;
- No edge may be referenced more than once by the same IfcEdgeLoop with the same sense. For this purpose, an edge which is not an oriented edge is considered to be referenced with the sense TRUE.
8.20.3.6.2 Entity inheritance
8.20.3.6.3 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. |
|
| Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes | |||
| IfcEdgeLoop (2) | |||
| 1 | EdgeList | LIST [1:?] OF IfcOrientedEdge |
A list of oriented edge entities which are concatenated together to form this path. |
| * | Ne | IfcInteger |
This attribute is formally derived. The number of elements in the edge list. |
8.20.3.6.4 Formal propositions
| Name | Description |
|---|---|
| IsClosed |
The start vertex of the first edge shall be the same as the end vertex of the last edge. This ensures that the path is closed to form a loop. |
|
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| IsContinuous |
The end vertex of each edge shall be the same as the start vertex of its successor. |
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8.20.3.6.5 Examples
8.20.3.6.6 Formal representation
ENTITY IfcEdgeLoop
SUBTYPE OF (IfcLoop);
EdgeList : LIST [1:?] OF IfcOrientedEdge;
DERIVE
Ne : IfcInteger := SIZEOF(EdgeList);
WHERE
IsClosed : (EdgeList[1].EdgeStart) :=: (EdgeList[Ne].EdgeEnd);
IsContinuous : IfcLoopHeadToTail(SELF);
END_ENTITY;