The SEDRIS Data Representation Model
APPENDIX A - Classes Connected Geometry Edge |
---|
An instance of this DRM class specifies a topological relationship between a <Geometry Node> and an ordered set of <Geometry Edge> instances, indicating that the <Geometry Node> connects the <Geometry Edge> instances.
Consider a <Geometry Edge> representing part of the boundary of a <Geometry Face>, which in turn represents a lake. The endpoints of the edge are provided by its associated <Geometry Node> instances.
In order to supply clean, high-level topological information, the data provider gives each of these < Geometry Nodes> a < Connected Geometry Edge> component, which relates it back to each <Geometry Edge> of which it is a part. This allows a consumer, encountering one of the < Geometry Nodes>, to determine what edges it participates in.
See Connected Edge Restrictions for the constraint in question.
At geometry topology levels 0 through 3, all of the <Geometry Edges> connected to a <Geometry Node> are located in the same topological surface; consequently, they can be ordered around the <Geometry Node>. However, at geometry topology level 4, <Geometry Edges> can connect to a <Geometry Node> from any direction in 3-dimensional space. When the <Geometry Edges> connected to a <Geometry Node> are not all located in the same topological surface, the < Geometry Edges> shall be organized into subsets, one for each separate topological surface, and the <Geometry Node> shall have a separate < Connected Geometry Edge> component for each such subset.
Yes. If a <Geometry Edge> forms a loop, so that its starting and ending <Geometry Nodes> are the same object, then that <Geometry Edge> will appear exactly twice in the collection of < Geometry Edge>s associated with the < Connected Geometry Edge>.
|