constructor(startingPosition, startingVelocity, speedLimit, size, sprite) {

    this.position = startingPosition;

    this.velocity = startingVelocity;

    this.speedLimit = speedLimit;

    this.size = size;

    this.sprite = sprite;

  }

​

  // Add the mover's velocity to its position.

  update() {

    // Calculate the distance (delta) to the mouse.

    let mouse = createVector(mouseX, mouseY);

    let delta = p5.Vector.sub(mouse, this.position);

    // Scale down the directional delta by 100.

    delta.div(100);

    this.acceleration = delta;

    // Acceleration changes the mover's velocity.

    this.velocity.add(this.acceleration);

    // Mover has a maximum speed.

    this.velocity.limit(this.speedLimit);

    // Velocity changes the mover's position.

    this.position.add(this.velocity);

  }

​

  // Display the mover as circle at its current position.

  display() {

    push();

    stroke(0);

    fill(175);

    translate(this.position.x, this.position.y);

    // If any key is pressed draw a "nose" indicating the

    // direction of the velocity.

    if (keyIsPressed) {

      let noseLength = map(this.velocity.mag(), 0, this.speedLimit, 0, this.size * 2);

      let direction = this.velocity.copy().setMag(noseLength);

      line(0, 0, direction.x, direction.y);

    }

    // Using arc tan to find velocity's angle of rotation.

    let heading = atan2(this.velocity.y, this.velocity.x);  

    // Rotate a 90 degrees counter-clockwise because sprites face "up".

    rotate(heading + PI/2);

    image(this.sprite, 0, 0);

​

    pop();

  }

}

​