3D Game Programming

The checkForTreasure() function does three things:

• If there is no active tree—if it is undefined, as described in Describing a
  Thing in JavaScript—then it returns immediately and does nothing else.


• If there is an active tree near the avatar, then checkForTreasure() calculates
  the distance between the tree and the avatar.


• If the distance is less than 500 , then the scorePoints() function is called.

Pythagorean Theorem Alert

If you have already learned a little bit of trigonometry, you may

have recognized the Pythagorean theorem in the checkForTreasure()

function. We used it to find the distance between two points: the

avatar and the active tree.

For now, we’ll keep the scorePoints() function very simple. Add it after the

checkForTreasure() function. We’ll use it only to add points to the scoreboard:

functionscorePoints() {

if(scoreboard.getTimeRemaining() === 0)return;

scoreboard.addPoints(10);

}

Be sure to add the first line in that function; otherwise players can get points

after time has expired!

The last thing we need to do is animate the jump so we can see it on the

screen. We combine two things that we’ve seen before: Tweens and a sine

function. Let’s add the animateJump() function next:

functionanimateJump() {

newTWEEN

.Tween({jump: 0})

.to({jump: Math.PI}, 500)

.onUpdate(function() {

marker.position.y = 200* Math.sin(this.jump);

})

.start();

}

That should do it! If you hide the code, you can now move about, find the

active tree, and jump to get treasure out of it. If you are very fast, you can

even jump multiple times next to the active tree to get multiple points.

This is already a fun game, but we can add a few tweaks to make it even

better.

Chapter 11. Project: Fruit Hunt • 104

Prepared exclusively for Michael Powell report erratum • discuss