Class

• <DRM Rendering Priority Level>

Superclass

• <DRM SEDRIS Abstract Base>

Subclass

• None.

Definition

An instance of this DRM class specifies the method used to describe the relative priority used to resolve occlusion between 2 or more overlapping (or potentially overlapping) objects.

Priority is indicated by the group ID (rendering_group) and priority index (rendering_priority). The rendering_priority is relative to the rendering_group, and is intended to assign priority order (or layer) to coplanar <DRM Polygon> instances or coplanar <DRM Feature> instances. A higher index indicates a higher rendering priority (rendered last).

Objects that do not contain a <DRM Rendering Priority Level> are assumed to have a rendering priority value of 0.

Class diagram

Figure 6.261 — DRM_Rendering_Priority_Level

Constraints

• Publishable Object

Example(s)

• A particular SEDRIS transmittal may represent a lake as a single <DRM Polygon> located inside of a much larger <DRM Polygon> that represents the surrounding terrain. The larger terrain polygon and the smaller lake polygon that it contains may be coplanar, so the modeler assigns a <DRM Rendering Priority Level> of 1 to the terrain <DRM Polygon> and a <DRM Rendering Priority Level> of 2 to the lake <DRM Polygon>, so that the lake polygon will be rendered on top of the terrain <DRM Polygon>.

• The side of a <DRM Model> can be represented by a brown <DRM Polygon>, and a window in the side of a <DRM Model> can be represented by a grey <DRM Polygon> where the grey <DRM Polygon> is coplanar with the brown <DRM Polygon>. The grey <DRM Polygon> would be given a higher <DRM Rendering Priority Level> than the brown <DRM Polygon> so that the window would be drawn correctly on the side of the <DRM Model> (where the <DRM Model> could be either a building or a vehicle).

• A Plan View Display (PVD) can display <DRM Point Feature>, <DRM Areal Feature>, and <DRM Linear Feature> instances. Since <DRM Features> are usually considered to be 'flat', many features are, by definition, coplanar. A <DRM Rendering Priority Level> can be used to indicate the relative drawing order (or layer) within a set of overlapping <DRM Features>. For example, it is common for a single <DRM Areal Feature> to cover the entire <DRM Environment Root> area as a 'default, background' <DRM Feature>. This <DRM Areal Feature> could be given a rendering priority of SE_RENDER_PRIORITY_BOTTOMMOST so that it would always be drawn first, and thus would always be in the background.

• The following instance diagram shows how <DRM Rendering Priority Level> can be used to override the layering of a fixed list of objects. The objects would render in this order: Polygon_C, Polygon_B, Polygon_A, Polygon_E, Polygon_F, Polygon_D.

  

  Figure 6.262 — <DRM Rendering Priority Level> example