Camera2Dと同様に使えるカメラ。サンプル付き。

TinyCamera2D

# include <Siv3D.hpp> // OpenSiv3D v0.1.5

struct TinyCamera2D
{
	TinyCamera2D() = default;
	void update()
	{
		const Transformer2D t1(Mat3x2::Translate(-sRegion.pos).scale(Window::Size().y / sRegion.size.y), true);
		//描画領域をマウスホイールで操作する
		dRegion = dRegion.scaledAt(Cursor::PosF(), 1 + Mouse::Wheel() / 10.0);

		//描画領域のスムーズな変化
		sRegion.pos = sRegion.pos*(1 - s) + dRegion.pos*s;
		sRegion.size = sRegion.size*(1 - s) + dRegion.size*s;
	}

	Transformer2D createTransformer() const
	{
		return Transformer2D(Mat3x2::Translate(-sRegion.pos).scale(Window::Size().y / sRegion.size.y), true);
	}

	double s = 0.25;	//視点追従性
	RectF dRegion = RectF(Window::Size());	//仮想描画領域
	RectF sRegion = dRegion;				//実描画領域
};

void Main()
{
	TinyCamera2D camera;
	
	Graphics::SetBackground(ColorF(0.8, 0.9, 1.0));

	const Font font(50);

	const Texture textureCat(Emoji(L"🐈"), TextureDesc::Mipped);

	while (System::Update())
	{
		camera.update();	//Camera2Dと一緒だが、Transformer2Dは使えない。。。
		{
			const auto t1 = camera.createTransformer();	//これも一緒

			font(L"Hello, Siv3D!🐣").drawAt(Window::Center(), Palette::Black);

			font(Cursor::Pos()).draw(20, 400, ColorF(0.6));

			textureCat.resize(80).draw(540, 380);

			Circle(Cursor::Pos(), 60).draw(ColorF(1, 0, 0, 0.5));
		}
	}
}