From da7b71b5040adf8a57903df84fe3ad9ccad4c477 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 13 Sep 2020 11:05:24 +0300
Subject: [PATCH] Add generator & pixmap mapping functions

---
 libs/pcg/include/psemek/pcg/map.hpp | 120 ++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 libs/pcg/include/psemek/pcg/map.hpp

diff --git a/libs/pcg/include/psemek/pcg/map.hpp b/libs/pcg/include/psemek/pcg/map.hpp
new file mode 100644
index 00000000..e0735799
--- /dev/null
+++ b/libs/pcg/include/psemek/pcg/map.hpp
@@ -0,0 +1,120 @@
+#pragma once
+
+#include <psemek/gfx/pixmap.hpp>
+#include <psemek/pcg/seamless.hpp>
+
+#include <vector>
+#include <type_traits>
+
+namespace psemek::pcg
+{
+
+	// TODO: return a proper generator instead of a lambda
+	template <typename Gen, typename F>
+	auto map_(Gen && gen, F && f)
+	{
+		return [gen = std::forward<Gen>(gen), f = std::forward<F>(f)](float x, float y)
+		{
+			return f(gen(x, y));
+		};
+	}
+
+	template <typename T, typename F, typename R = decltype(std::declval<F>()(std::declval<T>())),
+		typename = std::enable_if_t<std::is_same_v<T, R>>>
+	auto map(gfx::basic_pixmap<T> p, F && f)
+	{
+		for (std::size_t j = 0; j < p.height(); ++j)
+		{
+			for (std::size_t i = 0; i < p.width(); ++i)
+			{
+				p(i, j) = f(p(i, j));
+			}
+		}
+
+		return p;
+	}
+
+	template <typename T, typename F, typename R = decltype(std::declval<F>()(std::declval<T>())),
+		typename = std::enable_if_t<!std::is_same_v<T, R>>>
+	auto map(gfx::basic_pixmap<T> const & p, F && f)
+	{
+		gfx::basic_pixmap<R> result({p.width(), p.height()});
+
+		for (std::size_t j = 0; j < p.height(); ++j)
+		{
+			for (std::size_t i = 0; i < p.width(); ++i)
+			{
+				result(i, j) = f(p(i, j));
+			}
+		}
+
+		return result;
+	}
+
+	template <typename T, typename F>
+	auto map_neumann(gfx::basic_pixmap<T> const & pixmap, F && f, seamless_tag)
+	{
+		std::vector<T> n;
+		n.reserve(4);
+
+		using R = decltype(f(pixmap(0, 0), n));
+
+		std::size_t const w = pixmap.width();
+		std::size_t const h = pixmap.height();
+
+		gfx::basic_pixmap<R> result({w, h});
+
+		for (std::size_t j = 0; j < h; ++j)
+		{
+			for (std::size_t i = 0; i < w; ++i)
+			{
+				n.push_back(pixmap((i + 1) % w, j));
+				n.push_back(pixmap((i + w - 1) % w, j));
+				n.push_back(pixmap(i, (j + 1) % h));
+				n.push_back(pixmap(i, (j + h - 1) % h));
+
+				result(i, j) = f(pixmap(i, j), n);
+
+				n.clear();
+			}
+		}
+
+		return result;
+	}
+
+	template <typename T, typename F>
+	auto map_moore(gfx::basic_pixmap<T> const & pixmap, F && f, seamless_tag)
+	{
+		std::vector<T> n;
+		n.reserve(8);
+
+		using R = decltype(f(pixmap(0, 0), n));
+
+		std::size_t const w = pixmap.width();
+		std::size_t const h = pixmap.height();
+
+		gfx::basic_pixmap<R> result({w, h});
+
+		for (std::size_t j = 0; j < h; ++j)
+		{
+			for (std::size_t i = 0; i < w; ++i)
+			{
+				n.push_back(pixmap((i + 1) % w, j));
+				n.push_back(pixmap((i + 1) % w, (j + 1) % h));
+				n.push_back(pixmap(i, (j + 1) % h));
+				n.push_back(pixmap((i + w - 1) % w, (j + 1) % h));
+				n.push_back(pixmap((i + w - 1) % w, j));
+				n.push_back(pixmap((i + w - 1) % w, (j + h - 1) % h));
+				n.push_back(pixmap(i, (j + h - 1) % h));
+				n.push_back(pixmap((i + 1) % w, (j + h - 1) % h));
+
+				result(i, j) = f(pixmap(i, j), n);
+
+				n.clear();
+			}
+		}
+
+		return result;
+	}
+
+}