From c274126487ade4e872780c03aa1f90d9e19329b2 Mon Sep 17 00:00:00 2001
From: Matthias Hochsteger <matthias.hochsteger@tuwien.ac.at>
Date: Tue, 12 Feb 2019 15:01:34 +0100
Subject: [PATCH] Don't allow MPI-parallel GUI

---
 libsrc/meshing/meshclass.hpp    | 2 +-
 libsrc/visualization/visual.hpp | 6 +++---
 ng/ngappinit.cpp                | 6 +++++-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/libsrc/meshing/meshclass.hpp b/libsrc/meshing/meshclass.hpp
index 0f88ddcd..2aea32fe 100644
--- a/libsrc/meshing/meshclass.hpp
+++ b/libsrc/meshing/meshclass.hpp
@@ -33,7 +33,7 @@ namespace netgen
     T_POINTS points;
 
     // The communicator for this mesh. Just a dummy if compiled without MPI.  
-    NgMPI_Comm comm = MPI_COMM_NULL;
+    NgMPI_Comm comm;
     
     /// line-segments at edges
     Array<Segment, 0, size_t> segments;
diff --git a/libsrc/visualization/visual.hpp b/libsrc/visualization/visual.hpp
index 6db3fa18..493cb739 100644
--- a/libsrc/visualization/visual.hpp
+++ b/libsrc/visualization/visual.hpp
@@ -13,9 +13,9 @@ Visualization
 
 */
 
-#ifdef PARALLEL
-#define PARALLELGL
-#endif
+// #ifdef PARALLEL
+// #define PARALLELGL
+// #endif
 
 #include "../include/incopengl.hpp"
 
diff --git a/ng/ngappinit.cpp b/ng/ngappinit.cpp
index a83957a7..8c90d069 100644
--- a/ng/ngappinit.cpp
+++ b/ng/ngappinit.cpp
@@ -73,8 +73,12 @@ int main(int argc, char ** argv)
   MPI_Comm_size(MPI_COMM_WORLD, &netgen::ntasks);
   MPI_Comm_rank(MPI_COMM_WORLD, &netgen::id);
   
+  if(netgen::ntasks!=1)
+      throw ngcore::Exception("Netgen GUI cannot run MPI-parallel");
+
+  // MPI_COMM_WORLD is just a local communicator
+  netgen::ng_comm = ngcore::NgMPI_Comm{MPI_COMM_WORLD, false};
 
-  MPI_Comm_dup ( MPI_COMM_WORLD, &netgen::mesh_comm);
 #endif
 
   if ( netgen::id == 0 )