Math: Add rudimentary Frustum class

Signed-off-by: Squareys <Squareys@googlemail.com>

src/Magnum/Math/CMakeLists.txt

@@ -33,6 +33,7 @@ set(MagnumMath_HEADERS
     Dual.h
     DualComplex.h
     DualQuaternion.h
+    Frustum.h
     Functions.h
     Math.h
     TypeTraits.h

src/Magnum/Math/Frustum.h

@@ -0,0 +1,98 @@
+#ifndef Magnum_Math_Frustum_h
+#define Magnum_Math_Frustum_h
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016
+              Vladimír Vondruš <mosra@centrum.cz>
+    Copyright © 2016 Jonathan Hale <squareys@googlemail.com>
+
+    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.
+*/
+
+/** @file
+ * @brief Class @ref Magnum::Math::Frustum
+ */
+
+#include <Corrade/configure.h>
+#include <Corrade/Containers/ArrayView.h>
+#include <Corrade/Utility/Debug.h>
+
+#include "Magnum/Math/Matrix4.h"
+
+namespace Magnum { namespace Math {
+
+/**
+@brief Camera frustum
+
+*/
+template<class T> class Frustum {
+    public:
+
+        /**
+         * @brief Create a frustum from projection matrix
+         */
+        static Frustum<T> fromMatrix(const Matrix4<T>& m) {
+            return Frustum{
+                    mvp.row(3) + mvp.row(0),
+                    mvp.row(3) - mvp.row(0),
+                    mvp.row(3) + mvp.row(1),
+                    mvp.row(3) - mvp.row(1),
+                    mvp.row(3) + mvp.row(2),
+                    mvp.row(3) - mvp.row(2)
+                };
+        }
+
+        /**
+         * @brief Construct frustum from frustum planes
+         */
+        constexpr /*implicit*/ Frustum(const Vector4<T>& left, const Vector4<T>& right, const Vector4<T>& bottom, const Vector4<T>& top, const Vector4<T>& near, const Vector4& far): _data{left, right, bottom, top, near, far} {}
+
+        /**
+         * @brief Raw data
+         * @return One-dimensional array of length `24`.
+         */
+        T* data() { return _data[0].data(); }
+
+        /** @overload */
+        constexpr const T* data() const { return _data[0].data(); }
+
+        /**
+         * @brief The frustum planes
+         *
+         * In order left (index `0`), right (index `1`), bottom (index `1`),
+         * top (index `3`), near (index `4`), far (index `5`).
+         */
+        constexpr Corrade::Containers::StaticArrayView<6, Vector4<T>> planes() const { return _data; }
+
+        /**
+         * @brief Plane at given index
+         *
+         * In order left (index `0`), right (index `1`), bottom (index `1`),
+         * top (index `3`), near (index `4`), far (index `5`).
+         */
+        constexpr Vector4<T> operator[](std::size_t i) const { return _data[i]; }
+
+    private:
+        Vector4<T> _data[6];
+};
+
+}}
+
+#endif