class Ball {
  constructor(x, y, speedX, speedY) {
    this.x = x;
    this.y = y;
    this.speedX = speedX;
    this.speedY = speedY;
    this.size = 30;
  }

  move() {
    this.x += this.speedX;
    this.y += this.speedY;
  }

  display() {
    fill(100, 150, 255);
    noStroke();
    ellipse(this.x, this.y, this.size);
  }
}

let balls = [];

function setup() {
  createCanvas(400, 400);
  // 시작할 때 공 5개 생성
  for (let i = 0; i < 5; i++) {
    balls.push(new Ball(
      random(width), random(height),
      random(-3, 3), random(-3, 3)
    ));
  }
}

function draw() {
  background(30);
  for (let i = 0; i < balls.length; i++) {
    balls[i].move();
    // TODO: balls[i].bounce(); ← 이 메서드를 만들어보세요!
    balls[i].display();
  }
}

// TODO: mousePressed()로 클릭하면 공 추가하기
// TODO: keyPressed()로 키보드 이벤트 추가하기

class Particle {
  constructor(x, y) {
    this.x = x;
    this.y = y;
    this.speedX = random(-2, 2);
    this.speedY = random(-5, -1);
    this.size = random(5, 12);
  }

  update() {
    this.x += this.speedX;
    this.y += this.speedY;
    this.speedY += 0.1;  // 중력
  }

  display() {
    fill(255, 200);
    noStroke();
    ellipse(this.x, this.y, this.size);
  }
}

let particles = [];

function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(0, 0, 0, 40);  // 잔상 효과

  // 마우스 누르고 있으면 파티클 생성
  if (mouseIsPressed) {
    particles.push(new Particle(mouseX, mouseY));
  }

  for (let i = 0; i < particles.length; i++) {
    particles[i].update();
    particles[i].display();
  }

  // 화면 밖 파티클 제거
  for (let i = particles.length - 1; i >= 0; i--) {
    if (particles[i].y > height) {
      particles.splice(i, 1);
    }
  }
}

// TODO: 파티클에 색상 추가하기
// TODO: 키보드로 중력 방향 바꾸기

class Snowflake {
  constructor() {
    this.x = random(width);
    this.y = random(-50, 0);
    this.size = random(3, 8);
    this.speed = random(1, 3);
    this.drift = random(-0.5, 0.5);  // 좌우 흔들림
  }

  update() {
    this.y += this.speed;
    this.x += this.drift;
  }

  display() {
    fill(255);
    noStroke();
    ellipse(this.x, this.y, this.size);
  }
}

let snowflakes = [];

function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(20, 20, 40);

  // 매 프레임 눈 1개 생성
  snowflakes.push(new Snowflake());

  for (let i = 0; i < snowflakes.length; i++) {
    snowflakes[i].update();
    snowflakes[i].display();
  }

  // 화면 밖 눈 제거
  for (let i = snowflakes.length - 1; i >= 0; i--) {
    if (snowflakes[i].y > height) {
      snowflakes.splice(i, 1);
    }
  }
}

// TODO: 눈 색상이나 크기를 바꿔 보세요
// TODO: 마우스 근처에서 눈이 밀려나게 만들어보세요

class Ball {
  constructor(x, y, speedX, speedY) {
    this.x = x;
    this.y = y;
    this.speedX = speedX;
    this.speedY = speedY;
    this.size = random(15, 45);
    this.c = color(random(360), 80, 100);
  }

  move() {
    this.x += this.speedX;
    this.y += this.speedY;
  }

  bounce() {
    if (this.x > width || this.x < 0) {
      this.speedX *= -1;
      this.c = color(random(360), 80, 100);
    }
    if (this.y > height || this.y < 0) {
      this.speedY *= -1;
      this.c = color(random(360), 80, 100);
    }
  }

  display() {
    fill(this.c);
    noStroke();
    ellipse(this.x, this.y, this.size);
  }
}

let balls = [];

function setup() {
  createCanvas(400, 400);
  colorMode(HSB, 360, 100, 100);
  for (let i = 0; i < 20; i++) {
    balls.push(new Ball(
      random(width), random(height),
      random(-4, 4), random(-4, 4)
    ));
  }
}

function draw() {
  background(0, 0, 10, 50);  // 잔상 효과
  for (let i = 0; i < balls.length; i++) {
    balls[i].move();
    balls[i].bounce();
    balls[i].display();
  }
  // 정보 표시
  fill(0, 0, 100);
  noStroke();
  textSize(14);
  text("Bouncing Ball World", 10, 20);
  text("balls: " + balls.length + " | click to add | 'c' to clear", 10, 38);
}

function mousePressed() {
  balls.push(new Ball(
    mouseX, mouseY,
    random(-4, 4), random(-4, 4)
  ));
}

function keyPressed() {
  if (key === 'c') {
    balls = [];
  }
  if (key === 'r') {
    for (let i = 0; i < 10; i++) {
      balls.push(new Ball(
        random(width), random(height),
        random(-4, 4), random(-4, 4)
      ));
    }
  }
}