BulletTriangle.cpp

# include <Siv3D.hpp>

class Bullet
{
public:

	Bullet() = default;

	Bullet(const Vec2& startPos, const double angle)
		: m_startPos{ startPos }
		, m_angle{ angle } {}

	void update(double deltaTime = Scene::DeltaTime())
	{
		m_time += deltaTime;
	}

	void draw() const
	{
		m_startPos.asCircle(5).drawFrame(1);
		Line{ m_startPos, Arg::angle = m_angle, 800 }.draw(1);
		Circle{ getPos(), 10 }.draw();
	}

	Vec2 getPos() const
	{
		const Vec2 move = Vec2{ (Periodic::Triangle1_1(1.0s, (0.25 + m_time)) * 60), (-200 * m_time) }.rotate(m_angle);
		return (m_startPos + move);
	}

	double getTime() const
	{
		return m_time;
	}

private:

	Vec2 m_startPos{ 0, 0 };
	double m_time = 0.0;
	double m_angle = 0_deg;
};

void Main()
{
	Array<Bullet> bullets;
	int32 count = 0;

	while (System::Update())
	{
		if (MouseL.down())
		{
			bullets.push_back(Bullet{ Cursor::PosF(), ((count % 12) * 30_deg) });
			++count;
		}

		for (auto& bullet : bullets)
		{
			bullet.update();
		}

		bullets.remove_if([](const Bullet& bullet) { return (5.0 < bullet.getTime()); });

		for (const auto& bullet : bullets)
		{
			bullet.draw();
		}
	}
}