9.5.2

460 • CHAPTER 7
OBJECTS MENU • MANAGING YOUR ENVIRONMENT • 461
Distance
Environment fog lls the entire screen, stretching to innity. Distance refers to the fog’s intensity by
specifying the distance over which a light beam will lose its intensity completely. As the light loses
intensity, the fog color is added. If, for example, you have entered a value of 500 for Distance, a light
beam that starts off with 100% intensity will reduce to 20% after travelling 400 units; at the end of
a further 100 units, the light will have faded out completely, giving way to the fog color. The shorter
the distance, the thicker the fog.
Beams that penetrate the fog beyond the limit dened in Distance are absorbed completely by the fog
color — if you enable environment fog, you cannot see a sky or a background image.
Affect Background
Use this setting to determine whether or not existing Sky Objects or backgrounds should be affected
by the fog. If this setting is not active, fog will affect only “normal” object geometry, and the sky or
background will be visible, as if no fog were present. The fog’s values will be visible in the Material
Managers.
Foreground Object, Background Object
By default, only the top-most Foreground/Background object in the hierarchy will be rendered. If you
want to change the Foreground/Background object during an animation, use the Stage object with
a parameter track.
To render (or show in the viewport) a foreground or background image, you may assign a textured
material to a Foreground or Background object, just as you would to any other object. For transparent
areas, use the Alpha channel.
The Foreground object could be a cockpit and instrument display, or simply a notice of copyright or
authorship that you want to appear prominently in the scene.
Taking the copyright example further, the color in the image you use for the copyright message would
be in the shape of the actual text you wish to display. This texture would then be loaded into the Alpha
channel property of a material, from where you can use either the Alpha channel itself or clip mapping
to isolate and hide from rendering the background of the copyright texture.