POVRAY supports several types of light sources. For our purpose, only one will be introduced here. A light source has the following syntax:
light_source {
< a, b, c >
color color-name or rgb< r, g, b >
}
where < a, b, c > is the position of the light source and the
next line provides the color of the light.
The light source in POVRAY is something like the Sun. It emits light beams in all directions and the intensity is constant. For beginners, before you fully understand the interaction between the color of a light source and the color of a shape, please use only white light source.
If it is necessary, you may ant to use more than one light sources. But, the intensity of light is additive and as a result the surface of a shape may have a washed-out effect. Moreover, if the surface finish has a non-zero phong value, then there will be more than one highlights. In general, we could use a technique that photographers have been using for many years. That is, use a light source for major lighting (the main/major light) and a few weak light sources for feeling purpose. To have weak white light is equivalent to use various level of gray colors. POVRAY has Gray10, Grady20, ..., Gray90 which means 10%, 20%, ... 90% of a white light source.