From cfe44124c13454e59906d1582b12d9c036b872d0 Mon Sep 17 00:00:00 2001
From: tomhog <thomas.hogarth@gmail.com>
Date: Fri, 1 Feb 2019 18:16:42 +0000
Subject: [PATCH] Added mat3 for use when we need Normal matrix

---
 include/vsg/core/Value.h |   4 ++
 include/vsg/maths/mat3.h | 113 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 include/vsg/maths/mat3.h

diff --git a/include/vsg/core/Value.h b/include/vsg/core/Value.h
index 6e4f4feea6..a4fb704eff 100644
--- a/include/vsg/core/Value.h
+++ b/include/vsg/core/Value.h
@@ -15,6 +15,7 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
 #include <vsg/core/Data.h>
 #include <vsg/core/type_name.h>
 
+#include <vsg/maths/mat3.h>
 #include <vsg/maths/mat4.h>
 #include <vsg/maths/vec2.h>
 #include <vsg/maths/vec3.h>
@@ -141,6 +142,9 @@ namespace vsg
     VSG_value(ubvec3Value, ubvec3);
     VSG_value(ubvec4Value, ubvec4);
 
+    VSG_value(mat3Value, mat3);
+    VSG_value(dmat3Value, dmat3);
+
     VSG_value(mat4Value, mat4);
     VSG_value(dmat4Value, dmat4);
 
diff --git a/include/vsg/maths/mat3.h b/include/vsg/maths/mat3.h
new file mode 100644
index 0000000000..1e103440a3
--- /dev/null
+++ b/include/vsg/maths/mat3.h
@@ -0,0 +1,113 @@
+#pragma once
+
+/* <editor-fold desc="MIT License">
+
+Copyright(c) 2018 Robert Osfield
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+</editor-fold> */
+
+#include <vsg/maths/vec3.h>
+
+namespace vsg
+{
+
+    template<typename T>
+    struct t_mat3
+    {
+    public:
+        using value_type = T;
+        using column_type = t_vec3<T>;
+
+        column_type value[3];
+
+        constexpr t_mat3() :
+            value{{1, 0, 0},
+                  {0, 1, 0},
+                  {0, 0, 1}} {}
+
+        constexpr explicit t_mat3(value_type v) :
+            value{{v, 0, 0, 0},
+                  {0, v, 0, 0},
+                  {0, 0, v, 0},
+                  {0, 0, 0, v}} {}
+
+        constexpr t_mat3(value_type v0, value_type v1, value_type v2,
+                         value_type v3, value_type v4, value_type v5,
+                         value_type v6, value_type v7, value_type v8) :
+            value{{v0, v3, v6},
+                  {v1, v4, v7},
+                  {v2, v5, v8}} {}
+
+        constexpr explicit t_mat3(value_type v[9]) :
+            value{{v[0], v[3], v[6]},
+                  {v[1], v[4], v[7]},
+                  {v[2], v[5], v[8]}} {}
+
+        template<typename R>
+        t_mat3(const t_mat3<R>& rhs)
+        {
+            value[0] = rhs[0];
+            value[1] = rhs[1];
+            value[2] = rhs[2];
+        }
+
+        constexpr std::size_t size() const { return 9; }
+        constexpr std::size_t columns() const { return 3; }
+        constexpr std::size_t rows() const { return 3; }
+
+        column_type& operator[](std::size_t c) { return value[c]; }
+        column_type const& operator[](std::size_t c) const { return value[c]; }
+
+        value_type& operator()(std::size_t c, std::size_t r) { return value[c][r]; }
+        value_type operator()(std::size_t c, std::size_t r) const { return value[c][r]; }
+
+        template<typename R>
+        t_mat3& operator=(const t_mat3<R>& rhs)
+        {
+            value[0] = rhs[0];
+            value[1] = rhs[1];
+            value[2] = rhs[2];
+            return *this;
+        }
+
+        T* data() { return value[0].data(); }
+        const T* data() const { return value[0].data(); }
+    };
+
+    using mat3 = t_mat3<float>;
+    using dmat3 = t_mat3<double>;
+
+    VSG_type_name(vsg::mat3);
+    VSG_type_name(vsg::dmat3);
+
+    template<typename T>
+    T dot(const t_mat3<T>& lhs, const t_mat3<T>& rhs, int c, int r)
+    {
+        return lhs[0][r] * rhs[c][0] +
+               lhs[1][r] * rhs[c][1] +
+               lhs[2][r] * rhs[c][2];
+    }
+
+    template<typename T>
+    t_mat3<T> operator*(t_mat3<T> const& lhs, t_mat3<T> const& rhs)
+    {
+        return t_mat4<T>(dot(lhs, rhs, 0, 0), dot(lhs, rhs, 1, 0), dot(lhs, rhs, 2, 0),
+                         dot(lhs, rhs, 0, 1), dot(lhs, rhs, 1, 1), dot(lhs, rhs, 2, 1),
+                         dot(lhs, rhs, 0, 2), dot(lhs, rhs, 1, 2), dot(lhs, rhs, 2, 2));
+    }
+
+    template<typename T>
+    t_vec3<T> operator*(t_mat3<T> const& lhs, t_vec3<T> const& rhs)
+    {
+        return t_vec3<T>((lhs[0][0] * rhs[0] + lhs[1][0] * rhs[1] + lhs[2][0] * rhs[2]),
+                         (lhs[0][1] * rhs[0] + lhs[1][1] * rhs[1] + lhs[2][1] * rhs[2]),
+                         (lhs[0][2] * rhs[0] + lhs[1][2] * rhs[1] + lhs[2][2] * rhs[2]));
+    }
+
+} // namespace vsg