The SEDRIS Data Representation Model
APPENDIX A - Classes
Directional Light Behaviour
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Abstract Class Name: Directional Light Behaviour
Subclasses
Definition
Directional lights have a direction and lobe shape defined by a
component <Lobe Data> instance. The
lobe shape parameters are used
by sub-classes to specify cones, pyramids, blend geometry, etc.
Directional lights can have both a primary and a secondary colour. These
are specified by the <Colour> components of the
parent <Geometry> that have
colour_mapping values of
SE_CLR_MAPNG_LGT_RENDER_BHVR_PRIMARY and
SE_CLR_MAPNG_LGT_RENDER_BHVR_SECONDARY, respectively.
Primary Page in DRM Diagram:
Secondary Pages in DRM Diagram:
This class appears on only one page of the DRM class diagram.
Example
See concrete subclasses for examples.
FAQs
- How can I represent a simple bi-directional light?
- This can be done using either a <Cone
Directional Light> or a <Pyramid
Directional Light> with primary and secondary colours. Set the horizontal
and vertical widths of the lobe to 180 degrees and the invisible_behind to
SE_TRUE.
- Why does <Directional Light
Behaviour> have a (required) <Location> component?
Is it the location of the light?
- No; it does not represent the location of any light(s) that use this
behaviour. It is the reference location for the direction of the light
(as expressed the <Reference Vector>
components of the <Lobe Data>).
In most Spatial Reference Frames (SRFs), directions shall refer to a
location to account for the curvature of the earth. Even in linear
space SRFs, localized directions may be important (See Example 1).
Constraints
None.
Composed of (two-way)
Component of (two-way)(inherited)
Inherited Field Elements
This class has no inherited field elements.
Notes
Composed of Notes
lobe shape
Prev: Diffuse Colour.
Next: Distance Level Of Detail Data.
Up:Index.
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Last updated: October 1, 2002
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Copyright © 2002 SEDRIS™
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