From bdd32ad40f4b7fa2a97e8971a6758b3e2b5e99af Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Mon, 17 May 2021 20:20:39 +0300
Subject: [PATCH] Add rotate(vector, angle) function

---
 libs/geom/include/psemek/geom/vector.hpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libs/geom/include/psemek/geom/vector.hpp b/libs/geom/include/psemek/geom/vector.hpp
index aaf0b282..c86e33b0 100644
--- a/libs/geom/include/psemek/geom/vector.hpp
+++ b/libs/geom/include/psemek/geom/vector.hpp
@@ -320,6 +320,14 @@ namespace psemek::geom
 		return std::acos(std::max(T{-1}, std::min(T{1}, dot(v0, v1))));
 	}
 
+	template <typename T>
+	vector<T, 2> rotate(vector<T, 2> const & v, T angle)
+	{
+		auto const c = std::cos(angle);
+		auto const s = std::sin(angle);
+		return {v[0] * c - v[1] * s, v[0] * s + v[1] * c};
+	}
+
 	template <typename T, std::size_t N>
 	vector<T, N> pointwise_mult(vector<T, N> const & v0, vector<T, N> const & v1)
 	{