curriculum/challenges/english/blocks/learn-intermediate-oop-by-building-a-platformer-game/65b2bb4c279af3cd585ba777.md
You will need to add two more checkpoint detection rules to the checkpointDetectionRules array.
The first rule should check if the player's x position minus the player's width is less than or equal to the checkpoint's x position minus the checkpoint's width plus the player's width multiplied by 0.9. This will ensure that the player is close enough to the checkpoint to claim it.
The second rule should check if index is strictly equal to 0 or if the previous checkpoint(checkpoints[index - 1].claimed) is true. This will ensure that the player can only claim the first checkpoint or a checkpoint that has already been claimed.
You should have a checkpoint detection rule that checks for the following: player.position.x - player.width <= checkpoint.position.x - checkpoint.width + player.width * 0.9.
assert.match(code, /player\.position\.x\s*-\s*player\.width\s*<=\s*checkpoint\.position\.x\s*-\s*checkpoint\.width\s*\+\s*player\.width\s*\*\s*0\.9/i);
You should have a checkpoint detection rule that checks for the following: index === 0 || checkpoints[index - 1].claimed === true.
assert.match(code, /index\s*===\s*0\s*\|\|\s*checkpoints\[index\s*-\s*1\]\.claimed\s*===\s*true/i);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Learn Intermediate OOP by Building a Platformer Game</title>
<link rel="stylesheet" href="./styles.css" />
</head>
<body>
<div class="start-screen">
<h1 class="main-title">freeCodeCamp Code Warrior</h1>
<p class="instructions">
Help the main player navigate to the yellow checkpoints.
</p>
<p class="instructions">
Use the keyboard arrows to move the player around.
</p>
<p class="instructions">You can also use the spacebar to jump.</p>
<div class="btn-container">
<button class="btn" id="start-btn">Start Game</button>
</div>
</div>
<div class="checkpoint-screen">
<h2>Congrats!</h2>
<p>You reached the last checkpoint.</p>
</div>
<canvas id="canvas"></canvas>
<script src="./script.js"></script>
</body>
</html>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
:root {
--main-bg-color: #0a0a23;
--section-bg-color: #ffffff;
--golden-yellow: #feac32;
}
body {
background-color: var(--main-bg-color);
}
.start-screen {
background-color: var(--section-bg-color);
width: 100%;
position: absolute;
top: 50%;
left: 50%;
margin-right: -50%;
transform: translate(-50%, -50%);
border-radius: 30px;
padding: 20px;
padding-bottom: 5px;
}
.main-title {
text-align: center;
}
.instructions {
text-align: center;
font-size: 1.2rem;
margin: 15px;
line-height: 2rem;
}
.btn {
cursor: pointer;
width: 100px;
margin: 10px;
color: #0a0a23;
font-size: 18px;
background-color: var(--golden-yellow);
background-image: linear-gradient(#fecc4c, #ffac33);
border-color: var(--golden-yellow);
border-width: 3px;
}
.btn:hover {
background-image: linear-gradient(#ffcc4c, #f89808);
}
.btn-container {
display: flex;
align-items: center;
justify-content: center;
}
.checkpoint-screen {
position: absolute;
left: 0;
right: 0;
margin-left: auto;
margin-right: auto;
width: 100%;
text-align: center;
background-color: var(--section-bg-color);
border-radius: 20px;
padding: 10px;
display: none;
}
#canvas {
display: none;
}
@media (min-width: 768px) {
.start-screen {
width: 60%;
max-width: 700px;
}
.checkpoint-screen {
max-width: 300px;
}
}
const startBtn = document.getElementById("start-btn");
const canvas = document.getElementById("canvas");
const startScreen = document.querySelector(".start-screen");
const checkpointScreen = document.querySelector(".checkpoint-screen");
const checkpointMessage = document.querySelector(".checkpoint-screen > p");
const ctx = canvas.getContext("2d");
canvas.width = innerWidth;
canvas.height = innerHeight;
const gravity = 0.5;
let isCheckpointCollisionDetectionActive = true;
const proportionalSize = (size) => {
return innerHeight < 500 ? Math.ceil((size / 500) * innerHeight) : size;
}
class Player {
constructor() {
this.position = {
x: proportionalSize(10),
y: proportionalSize(400),
};
this.velocity = {
x: 0,
y: 0,
};
this.width = proportionalSize(40);
this.height = proportionalSize(40);
}
draw() {
ctx.fillStyle = "#99c9ff";
ctx.fillRect(this.position.x, this.position.y, this.width, this.height);
}
update() {
this.draw();
this.position.x += this.velocity.x;
this.position.y += this.velocity.y;
if (this.position.y + this.height + this.velocity.y <= canvas.height) {
if (this.position.y < 0) {
this.position.y = 0;
this.velocity.y = gravity;
}
this.velocity.y += gravity;
} else {
this.velocity.y = 0;
}
if (this.position.x < this.width) {
this.position.x = this.width;
}
if (this.position.x >= canvas.width - this.width * 2) {
this.position.x = canvas.width - this.width * 2;
}
}
}
class Platform {
constructor(x, y) {
this.position = {
x,
y,
};
this.width = 200;
this.height = proportionalSize(40);
}
draw() {
ctx.fillStyle = "#acd157";
ctx.fillRect(this.position.x, this.position.y, this.width, this.height);
}
}
class CheckPoint {
constructor(x, y, z) {
this.position = {
x,
y,
};
this.width = proportionalSize(40);
this.height = proportionalSize(70);
this.claimed = false;
};
draw() {
ctx.fillStyle = "#f1be32";
ctx.fillRect(this.position.x, this.position.y, this.width, this.height);
}
claim() {
this.width = 0;
this.height = 0;
this.position.y = Infinity;
this.claimed = true;
}
};
const player = new Player();
const platformPositions = [
{ x: 500, y: proportionalSize(450) },
{ x: 700, y: proportionalSize(400) },
{ x: 850, y: proportionalSize(350) },
{ x: 900, y: proportionalSize(350) },
{ x: 1050, y: proportionalSize(150) },
{ x: 2500, y: proportionalSize(450) },
{ x: 2900, y: proportionalSize(400) },
{ x: 3150, y: proportionalSize(350) },
{ x: 3900, y: proportionalSize(450) },
{ x: 4200, y: proportionalSize(400) },
{ x: 4400, y: proportionalSize(200) },
{ x: 4700, y: proportionalSize(150) },
];
const platforms = platformPositions.map(
(platform) => new Platform(platform.x, platform.y)
);
const checkpointPositions = [
{ x: 1170, y: proportionalSize(80), z: 1 },
{ x: 2900, y: proportionalSize(330), z: 2 },
{ x: 4800, y: proportionalSize(80), z: 3 },
];
const checkpoints = checkpointPositions.map(
(checkpoint) => new CheckPoint(checkpoint.x, checkpoint.y, checkpoint.z)
);
const animate = () => {
requestAnimationFrame(animate);
ctx.clearRect(0, 0, canvas.width, canvas.height);
platforms.forEach((platform) => {
platform.draw();
});
checkpoints.forEach(checkpoint => {
checkpoint.draw();
});
player.update();
if (keys.rightKey.pressed && player.position.x < proportionalSize(400)) {
player.velocity.x = 5;
} else if (keys.leftKey.pressed && player.position.x > proportionalSize(100)) {
player.velocity.x = -5;
} else {
player.velocity.x = 0;
if (keys.rightKey.pressed && isCheckpointCollisionDetectionActive) {
platforms.forEach((platform) => {
platform.position.x -= 5;
});
checkpoints.forEach((checkpoint) => {
checkpoint.position.x -= 5;
});
} else if (keys.leftKey.pressed && isCheckpointCollisionDetectionActive) {
platforms.forEach((platform) => {
platform.position.x += 5;
});
checkpoints.forEach((checkpoint) => {
checkpoint.position.x += 5;
});
}
}
platforms.forEach((platform) => {
const collisionDetectionRules = [
player.position.y + player.height <= platform.position.y,
player.position.y + player.height + player.velocity.y >= platform.position.y,
player.position.x >= platform.position.x - player.width / 2,
player.position.x <=
platform.position.x + platform.width - player.width / 3,
];
if (collisionDetectionRules.every((rule) => rule)) {
player.velocity.y = 0;
return;
}
const platformDetectionRules = [
player.position.x >= platform.position.x - player.width / 2,
player.position.x <=
platform.position.x + platform.width - player.width / 3,
player.position.y + player.height >= platform.position.y,
player.position.y <= platform.position.y + platform.height,
];
if (platformDetectionRules.every(rule => rule)) {
player.position.y = platform.position.y + player.height;
player.velocity.y = gravity;
};
});
checkpoints.forEach((checkpoint, index, checkpoints) => {
const checkpointDetectionRules = [
player.position.x >= checkpoint.position.x,
player.position.y >= checkpoint.position.y,
player.position.y + player.height <=
checkpoint.position.y + checkpoint.height,
isCheckpointCollisionDetectionActive,
--fcc-editable-region--
--fcc-editable-region--
];
});
}
const keys = {
rightKey: {
pressed: false
},
leftKey: {
pressed: false
}
};
const movePlayer = (key, xVelocity, isPressed) => {
if (!isCheckpointCollisionDetectionActive) {
player.velocity.x = 0;
player.velocity.y = 0;
return;
}
switch (key) {
case "ArrowLeft":
keys.leftKey.pressed = isPressed;
if (xVelocity === 0) {
player.velocity.x = xVelocity;
}
player.velocity.x -= xVelocity;
break;
case "ArrowUp":
case " ":
case "Spacebar":
player.velocity.y -= 8;
break;
case "ArrowRight":
keys.rightKey.pressed = isPressed;
if (xVelocity === 0) {
player.velocity.x = xVelocity;
}
player.velocity.x += xVelocity;
}
}
const startGame = () => {
canvas.style.display = "block";
startScreen.style.display = "none";
animate();
}
const showCheckpointScreen = (msg) => {
checkpointScreen.style.display = "block";
checkpointMessage.textContent = msg;
if (isCheckpointCollisionDetectionActive) {
setTimeout(() => (checkpointScreen.style.display = "none"), 2000);
}
};
startBtn.addEventListener("click", startGame);
window.addEventListener("keydown", ({ key }) => {
movePlayer(key, 8, true);
});
window.addEventListener("keyup", ({ key }) => {
movePlayer(key, 0, false);
});