class Particle
{
    float x, y;
    float vx, vy;
    float friction;
    
    Particle(float _x, float _y)
    {
        x = _x;
        y = _y;
        vx = random(-1, 1) * 0.1;
        vy = random(-1, 1) * 0.1;
        friction = 0.98;
    }
    
    void wallCollision()
    {
        if (x < 0)
        {
            x = 0;
            vx *= -friction;
        }
        else if (x > width)
        {
            x = width;
            vx *= -friction;
        }
        
        if (y < 0)
        {
            y = 0;
            vy *= -friction;
        }
        else if (y > height)
        {
            y = height;
            vy *= -friction;
        }
    }
    
    void update()
    {
        vx *= friction;
        vy *= friction;
        
        x += vx;
        y += vy;
    }
}