Lighting Introduction

The GL lighting model facility automatically calculates color using the geometries, colors, and properties of the currently bound material, lights, and lighting model. The lighting model subroutines can define multiple materials, lights, and lighting models. A lighting equation consists of one material, eight lights, and one lighting model.

A significant feature of GL is that the hardware can efficiently perform the lighting calculations needed to enhance the realism of the displayed geometry. Because different applications require different degrees of realism, the lighting facility in GL provides a variety of capabilities and features that allow you to control the degree of realism in the images produced by your application. You can use many of these realism features without a negative effect on the drawing performance.

When you look at an object in the real world, the color of that object (as perceived by your eye) depends on several parameters:

• The color, location, and direction of the light source or sources illuminating the object.
• The color and surface properties of the object itself.
• The position and view direction of the observer.

Although GL allows you to control all of these parameters, you will find that you can produce quite realistic images by using only a subset of the available parameters.