Abstract Class Name: Light Source

Superclass - SEDRIS Abstract Base

Subclasses

• Infinite Light
• Positional Light

Definition

A source of light emission. Lights up only the Geometry that appears in the section of the hierarchy beneath the object to which the Light Source is attached.

A Light Source must specify 3 colors (Ambient, Diffuse, Specular).

An optional Control Link can also be used to allow the light source to be turned on or off.

Primary Page in DRM Diagram:

• 21

Secondary Pages in DRM Diagram:

• 4

FAQs

The scoping concept used for lights can be taken further as other volumetric effects such as fog and sound are considered.

What about linear or area light sources?

This definition does not attempt to address linear or area light sources; it is fashioned after the OpenGL abstraction of light.

Why isn't my favorite light source addressed?

Only light sources specific to CIG lighting have been addressed.

Constraints

Composed of (one-way)

• one Ambient Color
• one Diffuse Color
• one Specular Color

Composed of (two-way)

• optionally, a Light Source Control Link

Component of (two-way)

• one or more Aggregate Geometries

Field Elements

Notes

Fields Notes

apply_to_children

 Flag to allow lights to limit their scope to only affecting their children.
 If apply_to_children is False then the light is assumed to apply globally.

override_positional_lights

 Flag to reset the current cumulative definition of local Light_Sources
 If override_positional_lights is True then all Positional Light
 Sources in the current scope are cleared.

override_infinite_lights

 Flag to reset the current cumulative definition of Infinite Light_Sources.
 If override_infinite_lights is True then all Positional Light Sources in
 the current scope are cleared.

active_light_value

 SE_TRUE = on, SE_FALSE = off
 this is the default/active state of the light