Add homogeneous coordinate functions

Add functions for transformations in 3 dimensional homogeneous space.
These include functions that generate transformation matrices and
perform matrix multiplication.

rtengine/homogeneouscoordinates.h

@@ -0,0 +1,75 @@
+/*
+ *  This file is part of RawTherapee.
+ *
+ *  Copyright (c) 2019 Lawrence Lee <billee@ucdavis.edu>
+ *
+ *  RawTherapee is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  RawTherapee is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with RawTherapee.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <array>
+
+namespace rtengine
+{
+
+namespace homogeneous
+{
+
+enum Axis {X, Y, Z};
+
+template <typename T>
+using Matrix = std::array<std::array<T, 4>, 4>;
+
+/**
+ * 3 dimensional homogeneous vector.
+ */
+template <typename T>
+using Vector = std::array<T, 4>;
+
+/**
+ * Creates a 3 dimensional transformation matrix for projection onto a plane.
+ * @param location Distance from the origin to the plane.
+ * @param normal Direction of the plane's normal.
+ */
+template <typename T>
+Matrix<T> projectionMatrix(T location, Axis normal);
+
+/**
+ * Creates a 3 dimensional transformation matrix for rotation.
+ * @param radians Rotation angle.
+ * @param axis Axis of rotation.
+ */
+template <typename T>
+Matrix<T> rotationMatrix(T radians, Axis axis);
+
+/**
+ * Creates a 3 dimensional transformation matrix for translation.
+ * @param x Translation in the the x-direction.
+ * @param y Translation in the the y-direction.
+ * @param z Translation in the the z-direction.
+ */
+template <typename T>
+Matrix<T> translationMatrix(T x, T y, T z);
+
+}
+
+template <typename T>
+homogeneous::Vector<T> operator*(const homogeneous::Matrix<T>& a, const homogeneous::Vector<T>& b);
+
+template <typename T>
+homogeneous::Matrix<T> operator*(const homogeneous::Matrix<T>& a, const homogeneous::Matrix<T>& b);
+
+}
+
+#include "homogeneouscoordinates.cc"