Class

• <DRM Face Direction>

Superclass

• <DRM SEDRIS Abstract Base>

Subclass

• None.

Definition

An instance of this DRM class specifies, for the associated relationship, whether the front or back of the target face is associated with the surface being described.

If the value of the front field is TRUE, the front face is associated with the given DRM object. Otherwise, it is the back face that is associated.

Class diagram

Figure 6.83 — DRM_Face_Direction

Constraints

• <DRM Face Direction> levels 0-3
• Publishable object

Example(s)

• Consider a <DRM Areal Feature> instance representing a grass-covered region, consisting of a single <DRM Feature Face> instance. The <DRM Face Direction> link object on the relationship between them is set to TRUE, indicating that the front (that is, the top) side of the face corresponds to the <DRM Areal Feature> instance.

• Consider a <DRM Polyhedron> instance specifying a room within a building and a <DRM Geometry Volume> instance representing the topological connectivity of the boundary of the room. The <DRM Polygon> instance representing a wall of the room that is an interior wall of the building has a <DRM Geometry Face> instance associated to the <DRM Polyhedron> instance through a <DRM Face Direction> link object with front field = FALSE.

  A second <DRM Polyhedron> instance representing a room on the other side of the same wall has a <DRM Geometry Volume> instance associated to the same <DRM Polygon> instance, but through a <DRM Face Direction> link object with front = TRUE.