3D Game Programming

Adding Sunlight

Our raft is going to be making jumps and bumping into things. This will be

more fun if there are shadows. For shadows, we need light. Let’s start our

code outline just below the START CODING line with an addSunlight() call:

addSunlight(scene);

Adding sunlight to a game is something of an art. Now that you’re a program-

mer, I’ll let you in on a secret: when programmers say that something is more

art than science, we really mean we’re just guessing. In other words, we try

some numbers and play with them until we think they look right. The following

should end up looking right for us (but feel free to play with the numbers

yourself!):

functionaddSunlight(scene) {

varsunlight =newTHREE.DirectionalLight();

sunlight.intensity = 0.5;

sunlight.castShadow = true;

sunlight.position.set(250, 250, 250);

sunlight.shadowCameraNear = 250;

sunlight.shadowCameraFar = 600;

sunlight.shadowCameraLeft = -200;

sunlight.shadowCameraRight = 200;

sunlight.shadowCameraTop = 200;

sunlight.shadowCameraBottom = -200;

sunlight.shadowMapWidth = 4096;

sunlight.shadowMapHeight = 4096;

scene.add(sunlight);

}

That looks like a lot of code for what might seem like simple light. Most of it

has to do with the art of 3D programming. In fact, only the first two lines are

really needed. They tell the light to be not too bright (intensity = 0.5) and to cast

shadows (castShadows = true).

So what are the rest of the lines for? Well, the remaining numbers help make

nice-looking shadows without forcing the computer to work too hard. You

can skip to the next section if you don’t need the details.

Adding a directional light to a scene is like adding the sun to the sky. The

position that we give a directional light in a scene describes the location of

the sun in the sky. Here it’s 250 to the right, 250 to the front, and 250 above

the center of the scene. So, when this directional light shines down, shadows

will be to the left, toward the back, and fall on the ground.

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Organizing Code • 187

Prepared exclusively for Michael Powell