From dd369c7c9c5c5395a8cc36cd7cff1acd1e13b112 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 20 Apr 2018 15:05:29 +1000
Subject: [PATCH] geom/plane: add make_plane convenience function

---
 geom/plane.hpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/geom/plane.hpp b/geom/plane.hpp
index 62757f5b..7a6fb37a 100644
--- a/geom/plane.hpp
+++ b/geom/plane.hpp
@@ -11,11 +11,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
- * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_PLANE_HPP
-#define __UTIL_PLANE_HPP
+#pragma once
 
 #include "../point.hpp"
 #include "../vector.hpp"
@@ -36,6 +35,16 @@ namespace util::geom {
     };
 
 
+    typedef plane<2,float> plane2f;
+    typedef plane<3,float> plane3f;
+
+    inline plane3f
+    make_plane (util::point3f a, util::point3f b, util::point3f c)
+    {
+        return plane3f (a, normalised (cross (b - a, c - a)));
+    }
+
+
     ///////////////////////////////////////////////////////////////////////////
     /// returns the normal for a plane
     template <size_t S, typename T>