Class

• <DRM Light Rendering Properties>

Superclass

• <DRM SEDRIS Abstract Base>

Subclass

• None.

Definition

An instance of this DRM class specifies that the aggregating <DRM Geometry Representation> instance is to be rendered so as to provide the illusion that the <DRM Geometry Representation> instance emits light, but unlike an actual <DRM Light Source> instance, the <DRM Geometry Representation> instance will not actually emit light.

The display_type field specifies whether the light is raster or calligraphic.

The light_diameter field specifies the size of the light, in pixels. The default value, 0,0, means “not applicable.”

The light_extinguishing_range field specifies the distance, in metres, at which the light is no longer seen. The default value, 0,0, means that it is always seen.

The random_area_light field specifies whether all lights at this level and in the associated component tree were originally part of an area with randomly generated lights.

The active_light_value field specifies the active state of the light, where TRUE = on, and FALSE = off. For a <DRM Light Rendering Properties> instance with a <DRM Light Rendering Properties Control Link> component X, where the active_expression_index field of X is non-zero, the value of the active_light_value field is obtained from X.

The candela_value field specifies the candela value of the light at full intensity. The default value, 0,0, means that the source had no candela value. For a <DRM Light Rendering Properties> instance with a <DRM Light Rendering Properties Control Link> component X, where the candela_value_expression_index field of X is non-zero, the value of the candela_value field is obtained from X.

Class diagram

Figure 6.152 — DRM_Light_Rendering_Properties

Constraints

• Homogeneous light rendering properties
• Publishable object

Example(s)

• Consider a <DRM Point> instance S representing a light attached to the exterior wall of a house, where S has a <DRM Light Rendering Properties> component. The house is surrounded by trees and other buildings, and S is located under an overhang. Consequently, the geometry of the environment surrounding the light is such that S cannot be seen from a distance of more than 500 metres, so the light_extinguishing_range field of S is set to 500.

• Consider a <DRM Point> instance S representing a streetlight on a pole mounted on an overpass, where S has a <DRM Light Rendering Properties> component. The light_extinguishing_range field of S is set to 0, indicating that the light can be seen from any distance.

• See the subclasses of the <DRM Light Rendering Behaviour> class for examples.