Game Development Reference
In-Depth Information
enemy, feel the ambiance of the space, and witness the effects of weapon ire. A virtual environment that
emulates a spiritual retreat, such as a monastery, needs to create a progression of enlightenment—both visu-
ally and emotionally. In a virtual environment that is being used to stage a theatrical presentation, you may
have a script with lighting cues to work from or the patterns of a dance performance to follow with your
lighting progression.
Once you have organized your thoughts regarding the kind of lighting and are comfortable with your
lighting plan and its capacity to support meaning, mood, and style, you need to document the actual posi-
tion and settings of the lights before you decide how they will be sequenced in time. A theatrical light-
ing designer would call this a “light plot” and would create a drawing by cross-referencing the location
of the circuits overhead with the stage setting below. From that information, the designer would make a
“magic sheet,” which is a simple one-page illustration utilizing various symbols to represent the location of
lights and circuits being used. You also can do this for virtual environments. Take an overhead screenshot
of the virtual landscape or building you are lighting. Bring that picture into your 2D graphics program
and make an overlay that indicates the position of each light with a number. Next to that, in a table format,
record the position (
x
,
y
,
z
), the light color and brightness, focus, and other settings for each light so you
have a quick organized reference sheet. Figure 8.2 provides one example of how you can set up this magic
sheet for yourself.
By utilizing a magic sheet, you are able to quickly set up the illumination ranges on the lights in your
environment and design the optimal pattern for them along the visitor's or game player's path. As your visitor
travels through the environment, the lights will come on and go out in a progression relative to your avatar's
camera and the draw distance the visitor has set up for his or her computer.
8.5 THE THREE BASIC ELEMENTS INVOLVED IN LIGHTING
A SCENE: LIGHTS, SHADERS, AND BAKING
The three main elements involved with lighting a virtual environment are light sources (inworld objects or
geometry); shaders, textures and materials that affect the surface appearance of objects to make them appear
to be shiny, transparent, glowing, and the like; and “baked lighting,” which is the creation of a texture with
the lighting prerendered on it, sort of like “painting” the light and shadow onto a surface of your objects in
a scene. Let's explore.
8.5.1 l
ighT
s
ourCes
and
T
heir
C
haraCTerisTiCs
Because Second Life and OpenSim use the OpenGL standard, the overall limit on light sources is 8 and
two of them are reserved for the Sun and Moon. The rendering of lighting is handled by your graphics
card, so results may vary from computer to computer. In Second Life and OpenSim, there are two basic
types of lights: the point light, which emits light in all directions like a light bulb, and the projector, which
works like a spotlight and gives off a cone or frustum of light. Both of these are made from setting the
parameters of the basic building element, the prim or object. For instance, you could have a prim that is
shaped like a hat that emits light in all directions (point light) or a prim shaped like a rock that projects a
beam with a pattern onto a surface nearby. If you have lots of prims available on your land, then feel free
to create a whole set of lighting prims; if you are getting short on server capacity for them, then look for
ways to make your building walls, furniture, and even landscaping objects do double duty and serve as
light sources.
