3D Game Programming

the shine—to three 0.9 values, which is pretty close to all 1.0 values that would

make white.

In other words, we see a little more of the shine:

Always Use Gray or White for Specular Colors

It’s possible to use any color you like for the specular attribute. Nor-

mally, however, it’s best to stick with gray or white. For instance,

the sunlight that we’re shining on our donut is white, but it’s still

possible to make the specular color yellow (change the last number

to 0.0). But that is just weird—white light creating a yellow shine.

We’ve covered emissive and specular; there are two other color-related properties

that we can set on Phong materials: ambient and plain-old color. The ambient

color applies only when using an “ambient” light—a light that is everywhere.

The color property is used only when there are no strong lights nearby. We’ll

stick with emissive and specular in this book—they make cooler-looking

objects.

12.4 Shadows

We’re shining a light on our donut, and yet there is no shadow. You can

usually skip rendering shadows, but sometimes they really help.

Don’t Overuse Shadows

It requires a lot of work for the computer to be able to draw shad-

ows, so use them only in spots that they really help. This is a tough

choice to make because shadows almost always make games look

better. But, as we’ll see, it makes the computer work harder on

something besides the main game and it’s a bit of a pain to set up

correctly.

First, we need to tell the renderer to expect shadows. Add the line setting the

shadowMapEnabled attribute just below the WebGL renderer line:

report erratum • discuss

Shadows • 113

Prepared exclusively for Michael Powell