The SEDRIS Data Representation Model
APPENDIX A - Classes
Light Rendering Properties

Class Name: Light Rendering Properties

Superclass - <SEDRIS Abstract Base>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

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

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

  1. Consider a <Point> instance S representing a light attached to the exterior wall of a house, where S has a <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.

  2. Consider a <Point> instance S representing a streetlight on a pole mounted on an overpass, where S has a <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.

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

FAQs

No FAQs supplied.

Constraints

Composed of (two-way)

Component of (two-way)

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_Point_Light_Display_Type display_type; 2
SE_Long_Float light_diameter; 3
SE_Long_Float light_extinguishing_range; 4
SE_Boolean random_area_light; 5
SE_Boolean active_light_value; 6
SE_Long_Float candela_value; 7

Notes

Composed of Notes


Light_Rendering_Properties_Control_Link

If a <Light Rendering Properties> instance is subject to dynamic control (that is, if it can be turned on and off or the candela value of the light can vary) it has a <Light Rendering Properties Control Link> component to express that control mechanism.

Fields Notes

display_type

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

light_diameter

The light_diameter field specifies the size of the light, in pixels. The default value, 0.0, means "not applicable."

light_extinguishing_range

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.

random_area_light

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.

active_light_value

The active_light_value field specifies the active state of the light, where SE_TRUE = on, and SE_FALSE = off. For a <Light Rendering Properties> instance with a <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.

candela_value

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 <Light Rendering Properties> instance with a <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.


Prev: Light Rendering Behaviour. Next: Light Rendering Properties Control Link. Up:Index.

Last updated: July 26, 2006 Copyright © 2006 SEDRIS