​

class Firework {

  constructor(x, y) {

    this.init(x, y); // Call the init method to initialize the properties of the firework

  }

​

  init(x, y) {

​

    // Initialize various properties of the firework

​

    this.size = 5;              // Size of the firework

    this.x = x;                 // Current x-coordinate

    this.y = y;                 // Current y-coordinate

    this.vx = random(-3, 3);    // Horizontal velocity

    this.vy = -random(5, 12);   // Vertical velocity (negative for upward motion)

    this.ay = 0.2;              // Vertical acceleration (gravity-like effect)

    this.px = this.x;           // Previous x-coordinate (for drawing)

    this.py = this.y;           // Previous y-coordinate (for drawing)

    this.particleCount = 300;   // Number of particles in the explosion

    this.particles = [];        // Array to store individual particles

    this.loadParticles();       // Initialize particles

    this.exploded = false;      // Indicates whether the firework has exploded

    this.particleEnded = 0;     // Count of particles that have ended (burned out)

    this.alive = true;          // Indicates whether the firework is active

  }

​

  move() {

    // Update the previous position and move the firework

    this.px = this.x;        // Update the previous x position

    this.py = this.y;        // Update the previous y position

    this.x += random(-2, 2); //move the firework - x coordinate

    this.y += this.vy;       //move the firework - x coordinate

  }

​

  accelerate() {

    this.vy += this.ay;      // Accelerate the firework by adjusting its vertical velocity

  }

​

  update() {

    if (this.exploded) {     // Update particles if the firework has exploded

      for (let i = 0; i < this.particleCount; i++) {

        this.particles[i].update();

      }

      if (this.particleCount === this.particleEnded) {

        this.alive = false;

      }

    } else {                 // Accelerate, move, and draw the firework until it explodes

      this.accelerate();

      this.move();

      this.draw();

      if (this.vy >= 0) {

        this.explode();

      }

    }

  }

​

  draw() {                  // Draw the firework as a line

    push();

    strokeWeight(this.size);

    stroke(0, 0, 95);

    line(this.x, this.y, this.px, this.py);

    pop();

  }

​

  loadParticles() {         // Initialize particles for the explosion

    let colorBase = random(100);

    for (let i = 0; i < this.particleCount; i++) {

      let color = (colorBase + i % 30) % 100;

      this.particles.push(new Particle(this, color));

    }

  }

​

  explode() {                                           // Explode the firework by adjusting particle positions

    this.exploded = true;

    for (let i = 0; i < this.particleCount; i++) {      // Randomly disperse particles from the firework's position

      this.particles[i].x = this.x + random(-0.2, 0.2);

      this.particles[i].y = this.y + random(-0.2, 0.2);

    }

  }

}

​

// Define a Particle class

​

class Particle {

  constructor(parent, color) {

    this.parent = parent;       // Reference to the parent Firework object

    this.size = random(7, 10);  // Size of the particle

    this.color = color;         // Color of the particle

    this.vx = random(-5, 5);    // Horizontal velocity of the particle

    this.vy = random(-5, 5);    // Vertical velocity of the particle

    this.x = 0;                 // Current x-coordinate of the particle

    this.y = 0;                 // Current y-coordinate of the particle

    this.gFactor = random(2.9, 3.5); // Factor for gravitational acceleration

    this.alive = true;          // Indicates whether the particle is active

  }

​

  move() {

    this.x += this.vx;          // Move the particle based on its velocity - x coordinate

    this.y += this.vy;          // Move the particle based on its velocity - y coordinate

  }

​

  accelerate() {

    // Apply gravitational acceleration to the particle's velocity

    // Calculate the distance between the particle and its parent firework

    let d = max(10, dist(this.x, this.y, this.parent.x, this.parent.y)); // Calculate gravitational force based on particle size and distance

    let ug = -200 * this.size / pow(d, this.gFactor);                    // Calculate horizontal and vertical components of the acceleration

    let ax = (this.parent.x - this.x) * ug;                              // Update the particle's velocity with the acceleration x - cood

    let ay = (this.parent.y - this.y) * ug;                              // Update the particle's velocity with the acceleration y - cood

    this.vx += ax;

    this.vy += ay + 0.016;                                               // Add a small vertical acceleration (air resistance)

    this.vx *= 0.9;                                                      // Apply some damping to the horizontal velocity

    this.vy *= 0.9;                                                      // Apply some damping to the vertical velocity

  }

​

  burn() {                            // Reduce the size of the particle over time and mark it as not alive when it's too small

    this.size *= 0.975;               // Gradually decrease the size

    if (this.size < 0.1) {

      this.alive = false;             // Mark the particle as not alive when it's very small

      this.parent.particleEnded += 1; // Increase the count of particles that have burned out

    }

  }

​

  update() {

    if (this.alive) {    // Update the particle's position, velocity, and size

      this.accelerate(); // Accelerate based on gravity and parent firework

      this.move();       // Move based on velocity

      this.draw();       // Draw the particle

      this.burn();       // Reduce size over time and mark as not alive if too small

    }

  }

​

  draw() {               // Draw the particle as a point

    push();

    stroke(this.color, this.color, 95);

    strokeWeight(this.size);

    point(this.x, this.y);

    pop();

  }

}

​

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