SpringSimulator

# include <Siv3D.hpp>	//OpenSiv3D v0.1.5
# include <HamFramework.hpp>
struct Node
{
	Vec2 pos;
	double mass;
	bool isFixed;
	Vec2 v;
	Array<Node*> spring;
	Vec2 f;
};

void Main()
{
	Window::SetTitle(L"SpringSimulator");
	Window::Resize(1280, 720);
	Window::SetBaseSize(Window::Size());

	Array<Node> nodes;

	const double interval = 32.0;
	const double naturalLength = 24.0;
	const double springConstant = 0.01;


	for (double x = 0; x < Window::Size().x; x += interval*1.73)
		for (double y = 0; y < Window::Size().y; y += interval)
			nodes.push_back({ Vec2(x,y), 10.0, true });

	for (double x = interval*1.73 / 2.0; x < Window::Size().x; x += interval*1.73)
		for (double y = interval / 2.0; y < Window::Size().y; y += interval)
			nodes.push_back({ Vec2(x,y), 10.0, true });

	nodes.push_back({ Vec2(-100,-100), 10.0, true });
	nodes.push_back({ Vec2(-124,-100), 10.0, false });
	nodes.push_back({ Vec2(-148,-100), 10.0, true });

	nodes.push_back({ Vec2(-80,-160), 10.0, false });
	nodes.push_back({ Vec2(-60,-160), 10.0, true });

	for (auto& n1 : nodes)
		for (auto& n2 : nodes)
			if ((n1.pos - n2.pos).length() <= interval && &n1 != &n2) n1.spring.push_back(&n2);

	for (auto& n : nodes)  if (n.spring.size() == 6) n.isFixed = false;

	Node* selectedNode = NULL;
	Camera2D camera;

	Array<double> forceLog;
	Array<double> speedLog;
	Node* observedNode = &nodes[0];

	Font font(14);

	while (System::Update())
	{
		//運動の計算
		for (auto& n : nodes) n.f = Vec2::Zero();
		for (auto& n : nodes)
		{
			for (auto& s : n.spring)
			{
				const double length = (s->pos - n.pos).length();
				if (length != 0) n.f -= springConstant*(s->pos - n.pos).normalized()*(naturalLength - length);
			}
		}
		for (auto& n : nodes)
		{
			if (!n.isFixed)
			{
				n.v += n.f / n.mass;
				n.pos += n.v;
			}
		}

		camera.update();
		{
			auto t = camera.createTransformer();

			//マウス操作
			if (!MouseL.pressed()) selectedNode = NULL;
			if (MouseL.down())
			{
				for (auto& n : nodes) if (Circle(n.pos, 4).mouseOver()) selectedNode = &n;
				observedNode = selectedNode;
				forceLog.clear();
				speedLog.clear();
			}
			if (selectedNode != NULL)
			{
				selectedNode->pos = Cursor::PosF();
				selectedNode->v = Vec2::Zero();
			}
			if (observedNode != NULL)
			{
				forceLog.push_front(observedNode->f.length());
				if (forceLog.size() > 512) forceLog.pop_back();
				speedLog.push_front(observedNode->v.length());
				if (speedLog.size() > 512) speedLog.pop_back();
			}

			//バネの描画
			for (auto& n : nodes)
			{
				for (auto& s : n.spring)
				{
					const double x = abs((n.pos - s->pos).length() - naturalLength)*0.05;
					Line(n.pos, s->pos).draw(Palette::White.lerp(Palette::Red, Min(1.0, x)));
				}
			}
			//おもりの描画
			for (auto& n : nodes)
			{
				if (selectedNode != NULL && &n == selectedNode) Circle(n.pos, 4).draw(Palette::Pink);
				else if (observedNode != NULL && &n == observedNode) Circle(n.pos, 4).draw(Palette::Lightgreen);
				else if (Circle(n.pos, 4).mouseOver()) Circle(n.pos, 4).draw(Palette::Red);
				else Circle(n.pos, 4).draw(n.isFixed ? Palette::Orange : Palette::White);

				if (observedNode != NULL && &n == observedNode) Circle(n.pos, 6).drawFrame(2, Palette::Lightgreen);
			}
		}
		camera.draw();

		//グラフの描画
		Rect(0, 0, 512, 160).draw(Palette::Black).drawFrame(2, Palette::Skyblue);

		double flMax = 0.01;
		for (auto& fl : forceLog) flMax = Max(flMax, fl);
		if (forceLog.size() >= 2)
		{
			for (int i = 0; i < forceLog.size() - 1; i++)
				Line(i, 130.0 - 128.0*forceLog[i] / flMax, i + 1, 128.0 - 128.0*forceLog[i + 1] / flMax).movedBy(0, 32).draw(2.0, Palette::Red);
		}

		double slMax = 0.01;
		for (auto& sl : speedLog) slMax = Max(slMax, sl);
		if (speedLog.size() >= 2)
		{
			for (int i = 0; i < speedLog.size() - 1; i++)
				Line(i, 130.0 - 128.0*speedLog[i] / slMax, i + 1, 128.0 - 128.0*speedLog[i + 1] / slMax).movedBy(0, 32).draw(2.0, Palette::Blue);
		}

		font(L"ForceMax ", flMax).draw(Vec2(0, 0), Palette::Red);
		font(L"SpeedMax ", slMax).draw(Vec2(0, 16), Palette::Blue);
	}
}