Island-Gen

# include <Siv3D.hpp> // OpenSiv3D v0.2.5

class Node
{
	Vec2	m_position;	//物理的な座標
	Point	m_point;	//仮想上の座標
	double	m_height;	//高度
	double	m_radius;	//半径
	Polygon	m_polygon;	//形状
	Array<Node*>	m_near_nodes;

public:
	Node(Point point, Vec2 position, double r)
		: m_point(point)
		, m_position(position)
		, m_height(0)
		, m_radius(r)
		, m_polygon(Shape2D::Hexagon(m_radius / 2.0 / Cos(30_deg), position).asPolygon())
	{}

	void	add_near_node(Node* node) { m_near_nodes.emplace_back(node); }

	//getter
	Vec2	get_position() const { return m_position; }
	double	get_height() const { return m_height; }
	Polygon	get_polygon() const { return m_polygon; }
	const Array<Node*>&	get_near_nodes() const { return m_near_nodes; }

	//setter
	void	set_height(double height) { m_height = height; }
};

class Field
{
	double		m_node_radius;
	Point		m_node_size;
	Grid<Node*> m_nodes;

public:
	Field(Vec2 size)
		: m_node_radius(2.0)
		, m_node_size(int(size.x / m_node_radius), int(size.y / Cos(30_deg) / m_node_radius))
		, m_nodes(m_node_size)
	{
		init();
	}

	//マップ初期化
	void init()
	{
		for (auto p : step(m_node_size))
		{
			//奇数列は半分ずらし、縦横比も変更
			m_nodes[p.y][p.x] = new Node(p, m_node_radius * Vec2(p.x + (p.y % 2 ? Cos(60_deg) : 0.0), p.y * Cos(30_deg)), m_node_radius);
		}

		//Nodeの相互接続
		for (auto p : step(m_node_size))
		{
			//周囲のリスト
			Array<Point> list;

			//奇数偶数列に応じた周囲のリストを登録
			if (p.y % 2) { list = Array<Point>({ { p.x, p.y - 1 },{ p.x + 1, p.y - 1 },{ p.x + 1, p.y },{ p.x + 1, p.y + 1 },{ p.x, p.y + 1 },{ p.x - 1, p.y } }); }
			else { list = Array<Point>({ { p.x - 1, p.y - 1 },{ p.x , p.y - 1 },{ p.x + 1, p.y },{ p.x , p.y + 1 },{ p.x - 1, p.y + 1 },{ p.x - 1, p.y } }); }

			//周囲の結びつきの登録
			for (auto& l : list)
			{
				if (l.x >= 0 && l.y >= 0 && l.x < m_node_size.x && l.y < m_node_size.y) { m_nodes[p.y][p.x]->add_near_node(m_nodes[l.y][l.x]); }
				else { m_nodes[p.y][p.x]->add_near_node(nullptr); }
			}
		}

		generate_terrain();
	}

	void generate_terrain()
	{
		PerlinNoise noise(Random(10000));

		for (auto p : step(m_node_size))
		{
			auto* n = m_nodes[p.y][p.x];
			auto h = Abs(noise.octaveNoise(n->get_position() * 0.0025, 10))
				* Pow(1.0 - Abs(m_node_size.x / 2 - p.x) / double(m_node_size.x / 2), 0.5)
				* Pow(1.0 - Abs(m_node_size.y / 2 - p.y) / double(m_node_size.y / 2), 0.5);

			n->set_height(h);
		}
	}

	void draw_hex()
	{
		//枠の描画
		for (auto p : step(m_node_size))
		{
			auto* n = m_nodes[p.y][p.x];

			n->get_polygon().draw(ColorF(Palette::Red, n->get_height()));

			if (n->get_height() < 0.1)
			{
				n->get_polygon().draw(Palette::Blue);
			}
			//n->get_polygon().drawFrame(1.0, ColorF(1.0, 0.25));
		}

		/*
		//接続線の描画
		for (auto p : step(m_node_size))
		{
			auto* n1 = m_nodes[p.y][p.x];

			for (auto* n2 : n1->get_near_nodes())
			{
				if (n2 != nullptr) { Line(n1->get_position(), n2->get_position()).draw(1.0, ColorF(1.0, 0.125)); }
			}
		}
		*/
	}

	//等高線の描画
	void draw_contour(double interval, double thickness)
	{
		for (double h = 0; h <= 1.0; h += interval)
		{
			for (auto p : step(m_node_size))
			{
				auto* tn = m_nodes[p.y][p.x];
				const auto& nns = tn->get_near_nodes();

				for (auto it = nns.begin(); it != nns.end(); it++)
				{
					auto* ln = *it;	//left
					auto* rn = (it == nns.end() - 1) ? *(nns.begin()) : *(it + 1);	//right

					if (ln == nullptr || rn == nullptr) { continue; }

					if (h > tn->get_height() && h < ln->get_height() && h < rn->get_height())
					{
						auto c1 = tn->get_position().lerp(ln->get_position(), (h - tn->get_height()) / (ln->get_height() - tn->get_height()));
						auto c2 = tn->get_position().lerp(rn->get_position(), (h - tn->get_height()) / (rn->get_height() - tn->get_height()));

						Line(c1, c2).draw(thickness);
					}

					if (h < tn->get_height() && h > ln->get_height() && h > rn->get_height())
					{
						auto c1 = ln->get_position().lerp(tn->get_position(), (h - ln->get_height()) / (tn->get_height() - ln->get_height()));
						auto c2 = rn->get_position().lerp(tn->get_position(), (h - rn->get_height()) / (tn->get_height() - rn->get_height()));

						Line(c1, c2).draw(thickness);
					}
				}
			}
		}
	}

	void draw()
	{
		draw_hex();
		draw_contour(0.1, 1.0);
		draw_contour(0.025, 0.5);
	}
};

Field* g_field = nullptr;

void Main()
{
	g_field = new Field(Vec2(500, 500));

	//ウィンドウの設定
	Window::Resize(640, 480);

	while (System::Update())
	{
		g_field->draw();

		if (KeyEnter.down()) { g_field->generate_terrain(); }
	}
}