Abstract Class Name: Directional Light Behavior
Subclasses
Definition
This abstract class indicates that all sub-classes below it have the
characteristics of a directional light.
Directional lights have a direction and lobe shape defined by a component
Lobe Data object. 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 color. These are
specified by the Color components of the parent
Geometry that have
color_mapping values of
SE_LIGHT_RENDERING_BEHAVIOR_PRIMARY_COLOR and
SE_LIGHT_RENDERING_BEHAVIOR_SECONDARY_COLOR, respectively.
Primary Page in DRM Diagram:
Example
- A 100 kilometer highway has regularly spaced lampposts. Each lamp has
Cone Directional Light
with Lobe Data pointing down. If all the lamps
use the same Cone Directional
Light, instance, then all the directions will be parallel. Due to
the curvature of the Earth, very few of the lights will shine directly
down; the others will be slightly skewed. If, instead, the set of lamps
is divided into smaller contiguous groups, each with its own
Cone Directional Light
instance using a Location near the center of
the group, the skewing effect will be greatly minimized.
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 colors. Set the horizontal
and vertical widths of the lobe to 180 degrees and the invisible_behind to
true.
- Why does Directional Light
Behavior 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
behavior. 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 must 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 (one-way)
Component of (one-way)(inherited)
Notes
Composed of Notes
lobe shape
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