Definition

The following constraints apply to instances of <Feature Node>/<Geometry Node> that are contained within an instance of <Feature Face>/<Geometry Face> or <Feature Volume>/<Geometry Volume>, respectively:

1. A <Feature Face> instance F shall have the following relationship with its associated <Feature Node> instances, if any exist.

   1. At any feature topology level, if F is associated with any <Feature Node> instance N, N shall lie within the external ring of F, if any, and shall not lie within any of the internal rings of F, if any.

   2. At feature topology levels 3 and higher, if a <Feature Node> instance N lies within the boundaries of F, N shall be associated with F.

   3. At any feature topology level, if no <Feature Node> instances lie within its boundaries, F shall not be associated with any <Feature Node> instances.

2. A <Feature Volume> instance V shall have the following relationship with its associated <Feature Node> instances, if any exist.

   1. At any feature topology level, if V is associated with any <Feature Node> instance N, N shall lie completely within the external shell of V, if any, and shall not lie within any of the internal shells of V, if any.

   2. At feature topology levels 5 and higher, if a <Feature Node> instance N lies within the boundaries of V, N shall be associated with V.

   3. At any feature topology level, if no <Feature Node> instances lie within its boundaries, V shall not be associated with any <Feature Node> instances.

3. A <Geometry Face> instance F shall have the following relationship with its associated <Geometry Node> instances, if any exist.

   1. At any geometry topology level, if F is associated with any <Geometry Node> instance N, N shall lie within the interior of F.

   2. At geometry topology levels 3 and higher, if a <Geometry Node> instance N lies within the interior of F, N shall be associated with F.

   3. At any geometry topology level, if no <Geometry Node> instances lie within its interior, F shall not be associated with any <Geometry Node> instances.

4. A <Geometry Volume> instance V shall have the following relationship with its associated <Geometry Node> instances, if any exist.

   1. At any geometry topology level, if V is associated with any <Geometry Node> instance N, N shall lie within the interior of V.

   2. At geometry topology levels 5 and higher, if a <Geometry Node> instance N lies within the interior of V, N shall be associated with V.

   3. At any geometry topology level, if no <Geometry Node> instances lie within its interior, V shall not be associated with any <Geometry Node> instances.

Rationale

The associations between <Feature Node> and <Feature Face>, and between <Feature Node> and <Feature Volume>, implement containment relationships. These topological relationships must be consistent, and must be consistent with the geometric representations of these objects.

The associations between <Geometry Node> and <Geometry Face>, and between <Geometry Node> and <Geometry Volume>, implement containment relationships. These topological relationships must be consistent, and must be consistent with the geometric counterparts of these objects.

Example

1. Consider a <Feature Node> instance N1 that is "floating" within the interior of a <Feature Volume> instance V1. N1 is contained within V1, and V1 contains N1.

2. Consider a <Geometry Node> instance N1 that is "floating" within the interior of a <Geometry Volume> instance V1. N1 is contained within V1, and V1 contains N1.

FAQs

Can a <Feature Node> instance N that is contained within the interior of a <Feature Face> instance F also be connected to a <Feature Edge> instance E?

Yes, provided that E does not bound F. This is only possible within a 3D SRF.

Can a <Geometry Node> instance N that is contained within the interior of a <Geometry Face> instance F also be connected to a <Geometry Edge> instance E?

Yes, provided that E does not bound F. This is only possible within a 3D SRF.

Can a <Feature Node> instance N that is contained within the interior of a <Feature Volume> instance V also be connected to a <Feature Edge> instance E?

Yes, provided that E does not bound any of the <Feature Face> instances that in turn bound V.

Can a <Geometry Node> instance N that is contained within the interior of a <Geometry Volume> instance V also be connected to a <Geometry Edge> instance E?

Yes, provided that E does not bound any of the <Geometry Face> instances that in turn bound V.