From b4228aca1e490c94f2454dfdc5e6ff3df8ca3948 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 30 Jul 2013 23:52:31 +1000
Subject: [PATCH] Add polar to cartesian operation for vectors

---
 vector.cpp | 6 ++++++
 vector.hpp | 5 ++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/vector.cpp b/vector.cpp
index 79585276..0b60fa21 100644
--- a/vector.cpp
+++ b/vector.cpp
@@ -266,6 +266,12 @@ util::vector<S>::normalised (void) const {
     return out;
 }
 
+//-----------------------------------------------------------------------------
+util::vector<2>
+util::polar_to_cartesian (const util::vector<2> &v) {
+    return { v.r * std::cos (v.t),
+             v.r * std::sin (v.t) };
+}
 
 //-----------------------------------------------------------------------------
 template <size_t S>
diff --git a/vector.hpp b/vector.hpp
index b606f5bb..875faa23 100644
--- a/vector.hpp
+++ b/vector.hpp
@@ -78,16 +78,15 @@ namespace util {
         void sanity (void) const;
     };
 
-    vector<3> cross (const vector<3>&, const vector<3>&);
+    vector<2> polar_to_cartesian (const vector<2>&);
 
+    vector<3> cross (const vector<3>&, const vector<3>&);
     vector<3> spherical_to_cartesian (const util::vector <3>&);
     vector<3> cartesian_to_spherical (const util::vector <3>&);
 
-
     typedef vector<2> vector2;
     typedef vector<3> vector3;
 
-
     template <size_t S> util::vector<S> operator* (double, const util::vector<S>&);
     template <size_t S> util::vector<S> operator+ (double, const util::vector<S>&);
     template <size_t S> util::vector<S> operator- (double, const util::vector<S>&);