CloudInvaders/js/cloud.js

const VELOCITY = [0.002, 0.0001];
const SHOOT_PROBABILITY = 0.0007;

class Cloud extends Entity {
    static shootProbability = SHOOT_PROBABILITY;

    constructor(...args) {
        super(...args);
        this.element.className = 'cloud';

        for (let i = 0; i < 10; i++) {
            const cloudParticle = document.createElement('div');
            cloudParticle.className = 'cloud-particle';
            cloudParticle.style.width = `${randRange(50, 80)}%`;
            cloudParticle.style.height = `${randRange(60, 100)}%`;
            cloudParticle.style.left = `${randRange(2, 98)}%`;
            cloudParticle.style.top = `${randRange(2, 98)}%`;
            cloudParticle.style.animationDelay = `${randRange(-10, 0)}s`;
            cloudParticle.style.animationDuration = `${randRange(0.5, 3)}s`;

            this.element.appendChild(cloudParticle);
        }
    }

    static reset() {
        this.shootProbability = SHOOT_PROBABILITY;
    }

    update(direction) {
        if (this.alive) {
            this.x += VELOCITY[0] * direction;
            this.y += VELOCITY[1];

            if (Math.random() < Cloud.shootProbability) {
                const raindrop = new RainDrop(this.x, this.y + 0.009);
                bullets.add(raindrop);
            }
        }
    }

    destroy() {
        super.destroy();
        Cloud.shootProbability += 0.0001;
    }
}