Game Development Reference
In the SkyDome Script settings in the Inspector, you can modify the specific
sky dome properties for a variety of effects. These include:
JULIANDATE: Sets the day of the year (with January 1st being day 1)
LONGITUDE and LATITUDE: Player's position coordinates on the
TIME: The time of day where 0 is midnight
Time Speed Factor: The speed at which time passes
Turbidity: The amount of scattering particles in the air. The higher the
turbidity, the longer the sunsets and sunrises last.
Cloud Speed 1 & 2: The speed at which the clouds move across the sky
Cloud Height 1 & 2: The relative distance the clouds appear to be from
FRay Factor: The affect of Rayleigh scattering, which determines how
blue the sky appears. With a setting of 0 there is no blue (the sky
FMie Factor: The effect of the Mie Theory with respect to the
brightness of the clouds
FSun Color Intensity: The brightness of the sun
For example, if you set the LONGITUDE to 18, the LATTITUDE to 65, and the
JULIANDATE to 1, which would position the player somewhere in Iceland
on the 1st of January (winter), you'll notice that the days are very short and
that the sun stays pretty much in the same position in the sky when it is up.
If you set the Turbidity to 10, the sunrise and sunset will be longer and the
sun's glare will appear brighter.
The previous two sections examined skies with clouds. Clouds on the
skybox were fixed and did not change position or color. Clouds on the sky
dome moved across the sky and exhibited turbulence. While the sky dome
method includes layers of clouds, giving the perception of depth, the player
can never get above or in among them. When you want to portray clouds in
a 3D fashion such that you could more around them, you need to examine
techniques for generating volumetric fog.
Volumetric fog is a more complex technique than the fog used previously.
Whereas the stock standard fog used in computer graphics applies a faded
out effect over all 3D assets in a scene, volumetric fog is contained within a
3D space. This makes it more processor intensive to render. However, this is
not a real issue on today's consoles and desktop machines.
The types of natural effects that can be achieved with volumetric fog
include low-lying clouds, mist, and dust as shown in Figure 7.36 . You use it
whenever you want to look at clouds from above or move through a variety
of fog densities. Whereas the default fog gives a set density, in volumetric
fog the player can walk through dense patches and then light patches.