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The SEDRIS Data Representation Model
APPENDIX A - Classes Light Rendering Properties |
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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.
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.
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.
See the subclasses of the <Light Rendering Behaviour> class for examples.
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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 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.
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.
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