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# Lighting Principles for Game Design

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Traditional stage lighting and 3D lighting share many similarities, most noticeably types and general placement. It's good to study traditional lighting to form an understanding of how important and effective light can be on your subjects, but be careful not to make the mistake of thinking that 3D lighting is just like real-world lighting. In fact, despite the many successful efforts to simulate real-world lighting in a 3D environment, the way to get there is not always as straightforward as one might think. Light in the real world behaves quite differently than light in a 3D scene. The trick is to use the tools you have to try and create a scene that is as accurate and appealing as possible. The following list lays out a common traditional lighting setup, and then the following section compares it to a 3D setup.

A great way to start lighting is to begin with a traditional setup, then change and build on top of that until you get the desired result. More broad stroke theory!

A successful lighting setup should include at least the following types of lights:

• Key light—A key light is the main light source in a scene. The key light is usually the most intense light and provides the majority of illumination and direction in the scene. A key light is best positioned at an angle with respect to the objects and camera to define the 3D forms. Figure 7.6 exemplifies a sphere with a key light only. We can see the direction, but the rest of the sphere is completely black and lost in the background.

• Figure 7.6 A sphere lit only by a key light positioned at an angle. The detail and form of the sphere are not as clear as if we added another light source.

• Fill light—Just like it sounds, a fill light brings out some of the shadow detail while still giving the object its form. A fill light is meant to bring out the details that are lost in shadow. Fill light works well at an angle alternate to that of the key light. You can see how a fill light more clearly defines the form of the sphere in Figure 7.7.

• Figure 7.7 A fill light brings out more form. Notice the point light has been added to the left of the sphere.

• Backlight (rim light)—A backlight is placed behind and slightly above or below the object to again help define the shape of the object. The backlight highlights the edges of an object and pulls it away from the background. Figure 7.8 shows the sphere with a backlight.

• Figure 7.8 The addition of the third light highlights the edge, helping give the sphere more dimension.

A simple three-light setup like this is a good way to start lighting in 3D. It's easy to get carried away when lighting and start to add tons of lights. This is typically not a good idea, not only because it gets confusing and causes a larger file size, but also because lights tend to add on top of one another until you have a completely blown-out scene. That's why we start with a simple setup and gradually add the details we need. Sound familiar?