<?phpnamespace App\Game;/** A small 4x2 mark: a bolt flying, a piece of debris. */final class Particle{ public int $y = 0; public int $x = 0; public int $dy = 0; public int $dx = 0; public bool $used = false; public function set(int $y, int $x, int $dy, int $dx): void { $this->y = $y; $this->x = $x; $this->dy = $dy; $this->dx = $dx; $this->used = true; } public function clear(): void { $this->used = false; $this->dy = 0; $this->dx = 0; }}