class Particle {
    constructor(x, y) {
        this.mass = 1;
        this.position = createVector(x, y);
        this.velocity = createVector(0, 0);
        this.gravity = createVector(0, 10); // G = 9.81
        this.hue = 0;
        this.saturation = 0;
        this.brightness = 100;
        this.alpha = 1;
        this.size = 8;
        this.lifetime = 0;
    }

    move(force) {
        if (this.position.y > 600) return;
        // 计算加速度
        const acceleration = createVector(0, 0);
        acceleration.add(this.gravity);
        if (force) acceleration.add(force.div(this.mass));
        // 计算时间差
        const duration = deltaTime / 1000;
        this.lifetime += duration;
        // 计算速度差及位移
        const deltaVelocity = acceleration.mult(duration);
        const averageVelocity = deltaVelocity.copy().div(2).add(this.velocity);
        const movement = averageVelocity.mult(duration);
        // 更新速度及位置
        this.velocity.add(deltaVelocity);
        this.position.add(movement);
        const report = {
            time: this.lifetime.toFixed(3),
            height: (height - this.position.y).toFixed(3),
            velocity: this.velocity.mag().toFixed(3),
        };
        print(report);
    }

    show() {
        noStroke();
        fill(this.hue, this.saturation, this.brightness, this.alpha);
        circle(this.position.x, this.position.y, this.size);
    }
}

class Particles {
    constructor() {}
    show() {}
}