From 519adcae3a6f5f1f7d3e0ff267be87af3677cbb4 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 13 Sep 2020 11:07:59 +0300
Subject: [PATCH] Add voronoi map generator

---
 libs/pcg/include/psemek/pcg/voronoi.hpp | 29 ++++++++++++++++
 libs/pcg/source/voronoi.cpp             | 46 +++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 libs/pcg/include/psemek/pcg/voronoi.hpp
 create mode 100644 libs/pcg/source/voronoi.cpp

diff --git a/libs/pcg/include/psemek/pcg/voronoi.hpp b/libs/pcg/include/psemek/pcg/voronoi.hpp
new file mode 100644
index 00000000..6a57cc37
--- /dev/null
+++ b/libs/pcg/include/psemek/pcg/voronoi.hpp
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <psemek/geom/point.hpp>
+#include <psemek/pcg/seamless.hpp>
+
+#include <vector>
+
+namespace psemek::pcg
+{
+
+	struct voronoi
+	{
+		voronoi(std::vector<geom::point<float, 2>> points);
+		voronoi(std::vector<geom::point<float, 2>> points, seamless_tag);
+
+		struct result_type
+		{
+			std::size_t index;
+			float distance;
+		};
+
+		result_type operator()(float x, float y) const;
+
+	private:
+		std::vector<geom::point<float, 2>> points_;
+		bool seamless_ = false;
+	};
+
+}
diff --git a/libs/pcg/source/voronoi.cpp b/libs/pcg/source/voronoi.cpp
new file mode 100644
index 00000000..42553c19
--- /dev/null
+++ b/libs/pcg/source/voronoi.cpp
@@ -0,0 +1,46 @@
+#include <psemek/pcg/voronoi.hpp>
+
+namespace psemek::pcg
+{
+
+	voronoi::voronoi(std::vector<geom::point<float, 2>> points)
+		: points_(std::move(points))
+		, seamless_{false}
+	{}
+
+	voronoi::voronoi(std::vector<geom::point<float, 2>> points, seamless_tag)
+		: points_(std::move(points))
+		, seamless_{true}
+	{}
+
+	voronoi::result_type voronoi::operator()(float x, float y) const
+	{
+		float v = std::numeric_limits<float>::infinity();
+		std::size_t index = 0;
+
+		for (std::size_t i = 0; i < points_.size(); ++i)
+		{
+			auto const & p = points_[i];
+
+			float dx = std::abs(p[0] - x);
+			float dy = std::abs(p[1] - y);
+
+			if (seamless_)
+			{
+				dx = std::min(dx, 1.f - dx);
+				dy = std::min(dy, 1.f - dy);
+			}
+
+			float const d = std::sqrt(dx * dx + dy * dy);
+
+			if (d < v)
+			{
+				v = d;
+				index = i;
+			}
+		}
+
+		return {index, v};
+	}
+
+}