From 17816021b9f53e667867ac8c097208b3ddbdd6a9 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 13 Mar 2018 14:36:38 +1100
Subject: [PATCH] coord/ops: add std::{cos,sin} overloads for coords

---
 coord/ops.hpp  | 26 ++++++++++++++++----------
 maths.hpp      | 10 ++++++++++
 quaternion.cpp |  7 +++----
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/coord/ops.hpp b/coord/ops.hpp
index d516372d..8c55da9e 100644
--- a/coord/ops.hpp
+++ b/coord/ops.hpp
@@ -1404,11 +1404,11 @@ namespace std {
 
 
 ///////////////////////////////////////////////////////////////////////////////
-#include <functional>
-
 #include "../hash.hpp"
 
+
 namespace std {
+    //-------------------------------------------------------------------------
     template <
         std::size_t S,
         typename T,
@@ -1427,6 +1427,8 @@ namespace std {
         }
     };
 
+
+    //-------------------------------------------------------------------------
     template <
         typename CoordT,
         typename = std::enable_if_t<
@@ -1435,16 +1437,20 @@ namespace std {
     >
     auto cos (CoordT val)
     {
-        CoordT out;
+        return ::util::apply<CoordT> (::util::cos<typename CoordT::value_type>, val);
+    }
 
-        std::transform (
-            std::begin (val),
-            std::end   (val),
-            std::begin (out),
-            [] (auto i) { return ::std::cos (i); }
-        );
 
-        return out;
+    //-------------------------------------------------------------------------
+    template <
+        typename CoordT,
+        typename = std::enable_if_t<
+            ::util::is_coord_v<CoordT>, void
+        >
+    >
+    auto sin (CoordT val)
+    {
+        return ::util::apply<CoordT> (::util::sin<typename CoordT::value_type>, val);
     }
 };
 
diff --git a/maths.hpp b/maths.hpp
index b23fa55d..1794c076 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -508,6 +508,16 @@ namespace util {
     }
 
 
+    //-------------------------------------------------------------------------
+    // thin wrappers around std trig identities.
+    //
+    // we have these because it's a little easier to qualify templates when
+    // passing function objects as compared to explicitly disambiguating raw
+    // functions (ie, with casts or typedefs).
+    template <typename ValueT> ValueT cos (ValueT theta) { return ::std::cos (theta); }
+    template <typename ValueT> ValueT sin (ValueT theta) { return ::std::sin (theta); }
+    template <typename ValueT> ValueT tan (ValueT theta) { return ::std::tan (theta); }
+
     ///////////////////////////////////////////////////////////////////////////////
     // combinatorics
 
diff --git a/quaternion.cpp b/quaternion.cpp
index 3d0d7975..0aa2dfdd 100644
--- a/quaternion.cpp
+++ b/quaternion.cpp
@@ -19,8 +19,7 @@
 
 #include "debug.hpp"
 #include "vector.hpp"
-
-#include <cmath>
+#include "coord/ops.hpp"
 
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -50,8 +49,8 @@ quaternion<T>::from_euler (vector<3,T> angles)
 {
     auto half = angles / 2;
 
-    auto c = cos (half);
-    auto s = sin (half);
+    auto c = std::cos (half);
+    auto s = std::sin (half);
 
     return {
         c.x * c.y * c.z - s.x * s.y * s.z,