CHAPTER 8
LIGHTING

What is true by lamplight is not always true by sunlight.

—Joseph Joubert

By the end of this chapter, you should:

Understand the fundamentals of light theory.

Understand concepts such as indirect illumination and lightmapping.

Be able to use the UDK light actors, including spot lights, directional lights, and point lights.

Be able to use emissive channels in materials to create light sources.

Understand the basics of using Unreal Lightmass.

This chapter concentrates on the subject of lighting. Lighting poses more technical problems and obstacles to achieving realism in real-time games than any other aspect of game creation. This is due primarily to the computational expense of calculating or simulating accurate lighting in real-time conditions, on a frame-by-frame basis. For this reason, most new, major innovations for video-game graphics tend to be related to lighting—typically new algorithms or techniques for faking lighting effects or for improving the way lighting is calculated.