irregular to regular

libs/MeshKernel/CMakeLists.txt

@@ -47,6 +47,7 @@ set(
   ${SRC_DIR}/Mesh2D.cpp
   ${SRC_DIR}/Mesh2DGenerateGlobal.cpp
   ${SRC_DIR}/Mesh2DIntersections.cpp
+  ${SRC_DIR}/Mesh2DToCurvilinear.cpp
   ${SRC_DIR}/MeshRefinement.cpp
   ${SRC_DIR}/Network1D.cpp
   ${SRC_DIR}/Operations.cpp
@@ -147,6 +148,7 @@ set(
   ${DOMAIN_INC_DIR}/Mesh2D.hpp
   ${DOMAIN_INC_DIR}/Mesh2DGenerateGlobal.hpp
   ${DOMAIN_INC_DIR}/Mesh2DIntersections.hpp
+  ${DOMAIN_INC_DIR}/Mesh2DToCurvilinear.hpp
   ${DOMAIN_INC_DIR}/MeshConversion.hpp
   ${DOMAIN_INC_DIR}/MeshInterpolation.hpp
   ${DOMAIN_INC_DIR}/MeshRefinement.hpp

libs/MeshKernel/include/MeshKernel/Mesh2DToCurvilinear.hpp

@@ -0,0 +1,89 @@
+//---- GPL ---------------------------------------------------------------------
+//
+// Copyright (C)  Stichting Deltares, 2011-2023.
+//
+// This program 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 version 3.
+//
+// This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// contact: [email protected]
+// Stichting Deltares
+// P.O. Box 177
+// 2600 MH Delft, The Netherlands
+//
+// All indications and logos of, and references to, "Delft3D" and "Deltares"
+// are registered trademarks of Stichting Deltares, and remain the property of
+// Stichting Deltares. All rights reserved.
+//
+//------------------------------------------------------------------------------
+
+#pragma once
+#include <memory>
+
+#include "MeshKernel/CurvilinearGrid/CurvilinearGrid.hpp"
+#include "MeshKernel/Definitions.hpp"
+#include "MeshKernel/Mesh2D.hpp"
+#include "MeshKernel/Point.hpp"
+#include "Utilities/LinearAlgebra.hpp"
+
+using namespace meshkernel::constants;
+
+namespace meshkernel
+{
+    /// @brief Construct a curvilinear grid from an unstructured mesh
+    class Mesh2DToCurvilinear
+    {
+    public:
+        /// @brief Constructor
+        /// @param[in] mesh The input unstructured mesh
+        explicit Mesh2DToCurvilinear(Mesh2D& mesh);
+
+        /// @brief Computes the curvilinear grid starting from a specific point
+        /// @param[in] point The point from which start growing the curvilinear mesh. The point must be inside a quadrangular face
+        /// @returns The curvilinear grid
+        std::unique_ptr<CurvilinearGrid> Compute(const Point& point);
+
+    private:
+        /// @brief Computes the local mapping of the nodes composing the face
+        [[nodiscard]] Eigen::Matrix<UInt, 2, 2> ComputeLocalNodeMapping(UInt face) const;
+
+        /// @brief Computes the node indices of the neighbouring faces
+        [[nodiscard]] UInt ComputeNeighbouringFaceNodes(const UInt face,
+                                                        const Eigen::Matrix<UInt, 2, 2>& localNodeMapping,
+                                                        const UInt d,
+                                                        const std::vector<bool>& visitedFace);
+
+        /// @brief Computes the final curvilinear matrix
+        [[nodiscard]] lin_alg::Matrix<Point> ComputeCurvilinearMatrix();
+
+        Mesh2D& m_mesh;       ///< The mesh to convert
+        std::vector<int> m_i; ///< The i indices of each node on the curvilinear grid
+        std::vector<int> m_j; ///< The j indices of each node on the curvilinear grid
+
+        std::array<std::array<int, 2>, 4> m_nodeFrom = {{{0, 0},
+                                                         {0, 0},
+                                                         {1, 0},
+                                                         {1, 1}}}; ///< starting edge node indices for each direction in the local mapping
+
+        std::array<std::array<int, 2>, 4> m_nodeTo = {{{0, 1},
+                                                       {1, 0},
+                                                       {1, 1},
+                                                       {0, 1}}}; ///< ending edge node indices for each direction in the local mapping
+
+        std::array<std::array<int, 2>, 4> m_directionsDeltas = {{{-1, 0},
+                                                                 {0, -1},
+                                                                 {1, 0},
+                                                                 {0, 1}}}; ///< increments for the new nodes depending on the node direction
+
+        const int n_maxNumRowsColumns = 1000000; ///< The maximum number of allowed rows or columns
+    };
+
+} // namespace meshkernel