From 086a40beb80cb9f906b5887454819a22c5eb6d32 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Simonis?= <simonisfrederic@gmail.com>
Date: Mon, 25 Nov 2024 10:10:34 +0100
Subject: [PATCH] Add API for runtime remeshing (#224)

---
 changelog-entries/224.md     |  1 +
 cyprecice/Participant.pxd    |  4 ++++
 cyprecice/cyprecice.pyx      | 36 ++++++++++++++++++++++++++++++++++++
 test/Participant.cpp         |  7 ++++++-
 test/test_bindings_module.py |  5 +++++
 5 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 changelog-entries/224.md

diff --git a/changelog-entries/224.md b/changelog-entries/224.md
new file mode 100644
index 00000000..088695ff
--- /dev/null
+++ b/changelog-entries/224.md
@@ -0,0 +1 @@
+- Added API function `reset_mesh()`
diff --git a/cyprecice/Participant.pxd b/cyprecice/Participant.pxd
index ffe9783b..01614ce0 100644
--- a/cyprecice/Participant.pxd
+++ b/cyprecice/Participant.pxd
@@ -65,6 +65,10 @@ cdef extern from "precice/Participant.hpp" namespace "precice":
 
         void setMeshTetrahedra (const string& meshName, vector[int] vertices)
 
+        # remeshing
+
+        void resetMesh (const string& meshName)
+
         # data access
 
         void writeData (const string& meshName, const string& dataName, vector[int] vertices, vector[double] values)
diff --git a/cyprecice/cyprecice.pyx b/cyprecice/cyprecice.pyx
index 557e8f04..3349fead 100644
--- a/cyprecice/cyprecice.pyx
+++ b/cyprecice/cyprecice.pyx
@@ -710,6 +710,42 @@ cdef class Participant:
 
         self.thisptr.setMeshTetrahedra (convert(mesh_name), cpp_vertices)
 
+    # remeshing
+
+
+    def reset_mesh (self, mesh_name):
+        """
+        Resets a mesh and allows setting it using set_mesh functions again.
+
+        Parameters
+        ----------
+        mesh_name : str
+            Name of the mesh to reset.
+
+        Notes
+        -----
+        This function is still experimental.
+        Please refer to the documentation on how to enable and use it.
+
+        Previous calls:
+            advance() has been called
+
+        Examples
+        --------
+        Reset a mesh with 5 vertices to have 3 vertices.
+
+        >>> positions = np.array([[1, 1], [2, 2], [3, 3], [4, 4], [5, 5]])
+        >>> mesh_name = "MeshOne"
+        >>> vertex_ids = participant.set_mesh_vertices(mesh_name, positions)
+        >>> # later in the coupling loop
+        >>> if remeshing_required():
+        >>>     participant.reset_mesh(mesh_name)
+        >>>     positions = np.array([[1, 1], [3, 3], [5, 5]])
+        >>>     vertex_ids = participant.set_mesh_vertices(mesh_name, positions)
+        """
+
+        self.thisptr.resetMesh (convert(mesh_name))
+
     # data access
 
     def write_data (self, mesh_name, data_name, vertex_ids, values):
diff --git a/test/Participant.cpp b/test/Participant.cpp
index 8a36f2af..74107e9c 100644
--- a/test/Participant.cpp
+++ b/test/Participant.cpp
@@ -237,6 +237,11 @@ void Participant::setMeshTetrahedra
     precice::span<const precice::VertexID> vertices)
 {}
 
+void Participant::resetMesh
+(
+    precice::string_view meshName)
+{}
+
 void Participant:: writeData
 (
   precice::string_view meshName,
@@ -320,4 +325,4 @@ std::string getVersionInformation()
   return fake_version;
 }
 
-} // namespace precice
\ No newline at end of file
+} // namespace precice
diff --git a/test/test_bindings_module.py b/test/test_bindings_module.py
index a34c3983..1f081f67 100644
--- a/test/test_bindings_module.py
+++ b/test/test_bindings_module.py
@@ -43,6 +43,11 @@ def test_requires_mesh_connectivity_for(self):
         fake_mesh_name = "FakeMesh"
         self.assertEqual(fake_bool, participant.requires_mesh_connectivity_for(fake_mesh_name))
 
+    def test_reset_mesh(self):
+        participant = precice.Participant("test", "dummy.xml", 0, 1)
+        fake_mesh_name = "FakeMesh"
+        participant.reset_mesh(fake_mesh_name)
+
     def test_set_mesh_vertices(self):
         participant = precice.Participant("test", "dummy.xml", 0, 1)
         fake_mesh_name = "FakeMesh"  # compare to test/SolverInterface.cpp, fake_mesh_name