Cumulonimbus Clouds in WorldBuilder: Page 3
Cloud
Shader also includes two controls for setting cloud color.
Cloud
Color shades the cloud areas which are directly illuminated.
Ambient
Color controls the shading for the darker parts of the cloud
(that is to say, the parts of the cloud in shadow or indirectly
illuminated). It' s important to keep in mind that Ambient
is the ‘base' color' for the cloud; if the Ambient
Color is brighter than the Cloud Color, the cloud will be brighter
overall.
Here
are a few different combinations of Cloud and Ambient Color.
Finally,
let' s apply a useful sub-property of Cloud Shader: Select
Light Sources.
This
control allows you to simulate certain kinds of lighting phenomena
which can occur when a cumulonimbus cloud is receiving reflected
or ‘bounced' light from the ground, or from another
cloud.
Add
a new Parallel Light to the scene. Move the light' s
target so that it is inside or above the cloud. Basically,
we want the new light pointing up at the cloud from below (be sure,
however, not to place the light beneath the landscape!).
The Asymmetry parameter controls the scattering of light within
the cloud' s volume. A low setting (0.1 or lower)
will cause the light to scatter ‘isotropically' (equally
in all directions) within the cloud, which will appear darker; a higher
setting will cause the light to scatter in a more uniform direction,
creating brighter areas within the cloud.
Reduce
the light' s intensity and use the Color button to
pick a green hue. You can even use the Color Picker' s
eyedropper cursor to directly select the green from the
rendered image.
Now
click on the Cumulonimbus0 object, and select the Select
Light Sources property. The original light source,
Parallel_Light_0, should already be highlighted. Now
Ctrl+click on Parallel_Light_1 to add that light to the
selection.
Note:
Only Parallel Lights are supported by the Select Light Sources
property. Spot and Point lights -even if they are
added to the scene- will not appear in the selection window.
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Render
the scene again. Now our cloud has a subtle, more
realistic ‘bounce light' effect visible on its
underside.
Here
are a few other variations making use of the Select Light
Sources property.
This
concludes our brief Cumulonimbus tutorial. We hope
you found it useful and interesting.
Watch
our website for future tutorials exploring Digital Element' s
line of virtual nature products.
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