paraFoam: attempts to launch ParaView with Mesa OpenGL if system OpenGL fails

A new "-empty" option launches ParaView without opening any files.  This enables users
to run ParaView using the paraFoam script for all data (OpenFOAM or otherwise), making
use of the automatic launching with Mesa if system OpenGL fails.

To view OpenFOAM case files, run "paraFoam".
To view other data files, run "paraFoam -empty" and open the files within ParaView.

bin/paraFoam

@@ -40,6 +40,7 @@ options:
   -block            use blockMesh reader  (uses .blockMesh extension)
   -builtin          use VTK builtin OpenFOAM reader  (uses .foam extension)
   -case <dir>       specify alternative case directory, default is the cwd
+  -empty            launch ParaView without opening any data files
   -region <name>    specify alternative mesh region
   -touch            only create the file  (eg, .blockMesh, .OpenFOAM, etc)
   -touchAll         create .blockMesh, .OpenFOAM files (and for all regions)
@@ -59,6 +60,38 @@ error() {
     exit 1
 }
 
+pvExec () {
+    paraview "$@" 2> /dev/null && return 0
+
+    pvFallback
+    paraview --mesa "$@"
+}
+
+pvFallback () {
+    cat <<EOF
+**********************************************************
+ParaView failed to open using available graphics hardware.
+Trying fallback to software rendering using MESA.
+**********************************************************
+EOF
+}
+
+noPVReader () {
+    cat<<EOF
+FATAL ERROR: The official reader module for OpenFOAM data does not exist on
+your system.  This means that the version of ParaView you are using was not
+compiled with OpenFOAM, or distributed with a packaged version of OpenFOAM.
+
+For information on packaged versions of OpenFOAM/ParaView and compilation of
+OpenFOAM/ParaView, see https://openfoam.org/download
+
+Alternatively, you might be able to view your OpenFOAM data with the reader
+module provided with ParaView by running:
+    paraFoam -builtin
+
+EOF
+}
+
 # We want to do nice exit when running paraview to give paraview opportunity
 # to clean up
 unset FOAM_ABORT
@@ -96,6 +129,10 @@ do
         cd "$2" 2>/dev/null || error "directory does not exist:  '$2'"
         shift 2
         ;;
+    -empty)
+        echo "Launching ParaView without opening any files."
+        pvExec && exit 0
+        ;;
     -region)
         [ "$#" -ge 2 ] || error "'$1' option requires an argument"
         regionName=$2
@@ -125,20 +162,9 @@ do
 done
 
 # Check that reader module has been built
-if [ $requirePV -eq 1 -a ! -f "$PV_PLUGIN_PATH/libPVFoamReader_SM.so" ]
-then
-    cat<< BUILDREADER
-
-FATAL ERROR: ParaView reader module libraries do not exist
-
-Please build the reader module before continuing:
-cd \$FOAM_UTILITIES/postProcessing/graphics/PVReaders
-./Allwclean
-./Allwmake
-
-BUILDREADER
-    exit 1
-fi
+[ $requirePV -eq 1 ] && \
+    ! [ -f "$PV_PLUGIN_PATH/libPVFoamReader_SM.so" ] && \
+    noPVReader && exit 1
 
 # Check for --data=... argument
 hasDataArg()
@@ -158,7 +184,6 @@ hasDataArg()
 
 hasDataArg "$@"
 
-
 # Get a sensible caseName from the directory name
 caseName=${PWD##*/}
 caseFile="$caseName.$extension"
@@ -179,7 +204,7 @@ fi
 case "${optTouch:-false}" in
 all)
     extension=OpenFOAM
-    if [ -f system/blockMeshDict -o -f constant/polyMesh/blockMeshDict ]
+    if [ -f system/blockMeshDict ] || [ -f constant/polyMesh/blockMeshDict ]
     then
         touch "$caseName.blockMesh"
         echo "Created '$caseName.blockMesh'"
@@ -189,12 +214,10 @@ all)
     # Discover probable regions
     for region in constant/*
     do
-        if [ -d "$region" -a -d "$region"/polyMesh ]
-        then
-            regionName=${region##*/}
-            touch "$caseName{$regionName}.$extension"
+        [ -d "$region" ] && [ -d "${region}/polyMesh" ] && \
+            regionName=${region##*/} && \
+            touch "$caseName{$regionName}.$extension" && \
             echo "Created '$caseName{$regionName}.$extension'"
-        fi
     done
     exit 0
     ;;
@@ -217,7 +240,7 @@ if [ "${hasData:-false}" = true ]
 then
 
     # Has --data=.., send directly to paraview
-    exec paraview "$@"
+    pvExec "$@"
 
 else
 
@@ -235,7 +258,8 @@ else
                     $blockMeshDictDir \
                 ;
             do
-                [ -s "$parentDir/$check" ] || {
+                [ -s "$parentDir/$check" ] || [ -s "$parentDir/$check.orig" ] ||
+                {
                     [ -n "$warn" ] && echo "$warn" 1>&2
                     echo "    $parentDir/$check" 1>&2
                     unset warn
@@ -250,7 +274,8 @@ else
                     $fvControls/fvSolution \
                 ;
             do
-                [ -s "$parentDir/$check" ] || {
+                [ -s "$parentDir/$check" ] || [ -s "$parentDir/$check.orig" ] ||
+                {
                     [ -n "$warn" ] && echo "$warn" 1>&2
                     echo "    $parentDir/$check" 1>&2
                     unset warn
@@ -263,7 +288,7 @@ else
         echo "Cannot locate OpenFOAM-format case files"
         printf "Would you like to open ParaView anyway <Y|n>:"
         read open
-        [ "$open" = "" ] || echo "$open" | grep -iqE "^y" && paraview
+        [ "$open" = "" ] || echo "$open" | grep -iqE "^y" && pvExec
         exit
     }
 
@@ -275,8 +300,8 @@ else
     }
 
     # For now filter out any ld.so errors. Caused by non-system compiler?
-    paraview --data="$caseFile" "$@" 2>&1 \
-        | fgrep -v 'Inconsistency detected by ld.so'
+    pvExec --data="$caseFile" "$@" 2>&1 \
+        | grep -v -F 'Inconsistency detected by ld.so'
 fi