Rule Name: Edges Bordering Faces

Definition

1. If a Feature Edge has a Bordered Feature Face component, then that Feature Edge must be part of the External Feature Face Ring or Internal Feature Face Ring of each Feature Face associated with that Bordered Feature Face.

   At feature topology level 3 or higher, the converse of this relationship is required to be present: if a Feature Edge is part of the External Feature Face Ring or Internal Feature Face Ring of a Feature Face, then that Feature Edge must have a Bordered Feature Face component, with which the Feature Face must be associated.

2. If a Geometry Edge has a Bordered Geometry Face component, then that Geometry Edge must be part of the External Geometry Face Ring of each Geometry Face associated with that Bordered Geometry Face.

   At geometry topology level 3 or higher, the converse of this relationship is required to be present: if a Geometry Edge is part of the External Geometry Face Ring of a Geometry Face, then that Geometry Edge must have a Bordered Geometry Face component, with which the Geometry Face must be associated.

Rationale

External Feature Face Ring is the one-directional topological relationship between a Regular Feature Face and the ordered collection of Feature Edges that form its outer boundary, so by definition, a Feature Edge that belongs to an External Feature Face Ring must border some Feature Face.

Similarly, External Geometry Face Ring is the one-directional topological relationship between a Geometry Face and the ordered collection of Geometry Edges that form its outer boundary, so by definition, a Geometry Edge that belongs to an External Geometry Face Ring must border some Geometry Face.

Internal Feature Face Ring is the one-directional topological relationship between a Regular Feature Face and the ordered collection of Feature Edges that form one of its inner boundaries, so by definition, a Feature Edge that belongs to an Internal Feature Face Ring must border some Feature Face.

Example

1. A Feature Edge X has a Bordered Feature Face component, which is associated with A CLASS="Feature_Face">Feature Faces A, B, and C. By the Edges Bordering Faces rule, X must be a component of
   • a Feature Face Ring component of A
     (either External or Internal)
   • a Feature Face Ring component of B
     (either External or Internal), and
   • a Feature Face Ring component of C
     (either External or Internal)
2. A Geometry Edge X has a Bordered Geometry Face component, which is associated with A CLASS="Geometry_Face">Geometry Faces A, B, and C. By the Edges Bordering Faces rule, X must be a component of
   • the External Geometry Face Ring component of A,
   • the External Geometry Face Ring component of B, and
   • the External Geometry Face Ring component of C

FAQs

If Bordered Feature Face objects exist in a given context within a transmittal, is that sufficent to give that context a feature topology level of 3?

No. See SE_FEATURE_TOPOLOGY_LEVEL_ENUM for the definitions of the various topology levels.

If Bordered Geometry Face objects exist in a given context within a transmittal, is that sufficent to give that context a geometry topology level of 3?

No. See SE_GEOMETRY_TOPOLOGY_LEVEL_ENUM for the definitions of the various topology levels.

If a given context within a transmittal (e.g., the context of an entire Environment Root of the transmittal) contains Geometry Topology but has geometry topology level less than 3, can that context legally contain Bordered Geometry Face objects?

Yes; they're just not required for topology levels less than 3.

I, as a consumer, have encountered a Feature Edge with a Bordered Feature Face component. Is the Bordered Feature Face guaranteed to provide a comprehensive list of all the Feature Faces that use the Feature Edge?

If the Feature Edge appears in a context with feature_topology_level of 3 or more, yes. Otherwise, the list of associated Feature Edges is not guaranteed to be comprehensive.

I, as a consumer, have encountered a Geometry Edge with a Bordered Geometry Face component. Is the Bordered Geometry Face guaranteed to provide a comprehensive list of all the Geometry Faces that use the Geometry Edge?

If the Geometry Edge appears in a context with geometry_topology_level of 3 or more, yes. Otherwise, the list of associated Geometry Edges is not guaranteed to be comprehensive.