3D Game Programming

Let’s see what happens if one of the legs is not attached to the avatar. In this

case, we’ll change the left_foot so that it’s added to the scene instead of the

avatar.

varleft_foot =newTHREE.Mesh(foot, cover);

left_foot.position.set(75, -125, 0);

scene.add(left_foot);

Run this, and the left foot goes missing.

Don’t underestimate the power of this concept. We’ll do some crazy things

with it later. For now, don’t forget to fix your left foot to the avatar!

4.4 Challenge: Start/Stop Animation

Remember the is_cartwheeling and is_flipping values from when we built the avatar

in Chapter 3, Project: Making an Avatar, on page 25? Let’s add two more if

statements to the keyboard event listener. If the C key, which the computer

thinks is the number 67 , is pressed, then the avatar should either start or

stop cartwheeling. If the F key, which the computer thinks is 70 , is pressed,

then the flip routine should start or stop.

Hint: switch between true and false with the not operator. In JavaScript, the not

operator is an exclamation point, !. You can use this not operator to assign

the value of is_cartwheeling to the opposite of its original value with something

like is_cartwheeling = !is_cartwheeling. We’ll see this again in Booleans.

Hopefully, you were able to get it working yourself. Here is the animate() function

that handles the cartwheeling and flipping.

varis_cartwheeling = false;

varis_flipping = false;

functionanimate() {

requestAnimationFrame(animate);

if(is_cartwheeling) {

avatar.rotation.z = avatar.rotation.z + 0.05;

}

report erratum • discuss

Challenge: Start/Stop Animation • 39

Prepared exclusively for Michael Powell