Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/libigl/igl/quadric_binary_plus_operator.h

@@ -0,0 +1,35 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2016 Alec Jacobson <alecjacobson@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+#ifndef IGL_QUADRIC_BINARY_PLUS_OPERATOR_H
+#define IGL_QUADRIC_BINARY_PLUS_OPERATOR_H
+#include "igl_inline.h"
+#include <Eigen/Core>
+#include <tuple>
+
+namespace igl
+{
+  // A binary addition operator for Quadric tuples compatible with qslim,
+  // computing c = a+b
+  //
+  // Inputs:
+  //   a  QSlim quadric
+  //   b  QSlim quadric
+  // Output
+  //   c  QSlim quadric
+  //
+  IGL_INLINE std::tuple< Eigen::MatrixXd, Eigen::RowVectorXd, double> 
+    operator+(
+      const std::tuple< Eigen::MatrixXd, Eigen::RowVectorXd, double>  & a, 
+      const std::tuple< Eigen::MatrixXd, Eigen::RowVectorXd, double>  & b);
+}
+
+#ifndef IGL_STATIC_LIBRARY
+#  include "quadric_binary_plus_operator.cpp"
+#endif
+
+#endif