let enemyImg;

let backgroundImage;

let player;

let bullets = [];

let enemies = [];

let enemySpawnTimer = 0;

let gameOver = false;

let score = 0;

let startScreen = true;

​

function preload() {

    playerImg = loadImage('https://raw.githubusercontent.com/CodingWith-Adam/space-invaders/main/images/player.png');

    enemyImg = loadImage('https://raw.githubusercontent.com/CodingWith-Adam/space-invaders/main/images/enemy1.png');

    backgroundImage = loadImage('https://raw.githubusercontent.com/CodingWith-Adam/space-invaders/main/images/space.png');

}

​

function setup() {

    createCanvas(600, 600);

    player = new Player();

}

​

function draw() {

    if (mouseIsPressed === true) {

    startScreen = false;

  }

​

  if (startScreen === true) {

    background(backgroundImage);

    fill("white");

    text("Click to Play", 225, 300);

    textSize(32)

    image(playerImg, 500, 500, 50, 50);

    image(enemyImg, 500, 100, 50, 40);

    image(enemyImg, 450, 150, 50, 40);

    image(enemyImg, 250, 100, 50, 40);

    image(enemyImg, 100, 210, 50, 40);

    image(enemyImg, 10, 80, 50, 40);

    fill('yellow')

    startscreenbullets(500, 450);

    startscreenbullets(525, 390);

    startscreenbullets(500, 330);

    startscreenbullets(525, 270);

    return;

  }

    if (!gameOver) {

        background(backgroundImage);

        player.update(mouseX);

        player.display();

​

    for (let i = bullets.length - 1; i >= 0; i--) {

        bullets[i].move();

        bullets[i].display();

        if (bullets[i].offscreen()) {

                bullets.splice(i, 1);

        } else {

        for (let j = enemies.length - 1; j >= 0; j--) {

        if (bullets[i].hits(enemies[j])) {

        bullets.splice(i, 1);

        enemies.splice(j, 1);

        score += 150;

        break;

                }

            }

        }

    }

​

    for (let i = enemies.length - 1; i >= 0; i--) {

        let enemy = enemies[i];

        enemy.move();

        enemy.display();

        if (enemy.hits(player)) {

            gameOver = true;

        }

        if (enemy.y > height) {

            enemies.splice(i, 1);

            score -= 100;

        }

    }

​

    if (enemySpawnTimer <= 0) {

        enemies.push(new Enemy(random(width - 40), 0));

        enemySpawnTimer = 30;

    } else {

        enemySpawnTimer--;

    }

​

    textAlign(LEFT);

    textSize(20);

    fill(255);

    text("Score: " + score, 20, 30);

    } else {

    textAlign(CENTER);

    textSize(32);

    fill(255);

    text("Game Over", width / 2, height / 2);

    }

}

​

function startscreenbullets(x, y){

  rect(x, y, 10, 20)

}

​

function mousePressed() {

    bullets.push(new Bullet(player.x + player.width / 2, player.y));

}

​

class Player {

    constructor() {

        this.width = 50;

        this.height = 20;

        this.y = height - this.height - 10;

        this.x = width / 2 - this.width / 2;

    }

​

    display() {

        image(playerImg, this.x, this.y, this.width, this.height);

    }

​

    update(mouseX) {

        this.x = constrain(mouseX - this.width / 2, 0, width - this.width);

    }

}

​

class Bullet {

    constructor(x, y) {

        this.width = 5;

        this.height = 20;

        this.x = x - this.width / 2;

        this.y = y;

    }

​

    display() {

        fill('yellow');

        rect(this.x, this.y, this.width, this.height);

    }

​

    move() {

        this.y -= 7;

    }

​

    offscreen() {

        return this.y < 0;

    }

​

    hits(enemy) {

        return collideRectCircle(enemy.x, enemy.y, enemy.width, enemy.height, this.x, this.y, this.width);

    }

}

​

class Enemy {

    constructor(x, y) {

        this.width = 40;

        this.height = 20;

        this.x = x;

        this.y = y;

    }

​

    display() {

        image(enemyImg, this.x, this.y, this.width, this.height);

    }

​

    move() {

        this.y += 2;

    }

​

    hits(player) {

        return collideRectRect(player.x, player.y, player.width, player.height, this.x, this.y, this.width, this.height);

    }

}