Added a stripped down MPI version of standalone: standalone_mpi. In fact, it's more like a pure simulation module since I've dropped real-time rendering and other old parts that do not work with MPI without heavy modifications. The most important functionalities in addition to simulation have already been adapted to work with MPI (samples/benchmark and samples/mpi) so there's no need to re-create them in standalone_mpi. The current version of standalone_mpi is able to run a basic simulation and I get an agreement with non-mpi and mpi versions after 100 timesteps. There's also draft that's a direct adaptation of what's currently in standalone/simulation.cc (it should be 100% equivalent), but it's currently commented out as I haven't done extensive tests with it.

samples/standalone_mpi/host_memory.h

@@ -0,0 +1,49 @@
+/*
+    Copyright (C) 2014-2020, Johannes Pekkila, Miikka Vaisala.
+
+    This file is part of Astaroth.
+
+    Astaroth 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.
+
+    Astaroth 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 Astaroth.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file
+ * \brief Brief info.
+ *
+ * Detailed info.
+ *
+ */
+#pragma once
+#include "astaroth.h"
+
+// clang-format off
+#define AC_FOR_INIT_TYPES(FUNC)\
+        FUNC(INIT_TYPE_RANDOM), \
+        FUNC(INIT_TYPE_XWAVE), \
+        FUNC(INIT_TYPE_GAUSSIAN_RADIAL_EXPL), \
+        FUNC(INIT_TYPE_ABC_FLOW) , \
+        FUNC(INIT_TYPE_SIMPLE_CORE), \
+        FUNC(INIT_TYPE_VEDGE), \
+        FUNC(INIT_TYPE_VEDGEX), \
+        FUNC(INIT_TYPE_RAYLEIGH_TAYLOR), \
+        FUNC(INIT_TYPE_RAYLEIGH_BENARD)
+// clang-format on
+
+#define AC_GEN_ID(X) X
+typedef enum { AC_FOR_INIT_TYPES(AC_GEN_ID), NUM_INIT_TYPES } InitType;
+#undef AC_GEN_ID
+
+extern const char* init_type_names[]; // Defined in host_memory.cc
+
+void acmesh_init_to(const InitType& type, AcMesh* mesh);