Set USE_OCC to ON by default

CMakeLists.txt

@@ -17,7 +17,7 @@ option( USE_PYTHON  "build with python interface" ON )
 cmake_dependent_option( PREFER_SYSTEM_PYBIND11  "Use system wide PyBind11" OFF "USE_PYTHON" OFF)
 option( USE_MPI     "enable mpi parallelization" OFF )
 option( USE_MPI4PY  "enable mpi4py interface" ON )
-option( USE_OCC     "build with OpenCascade geometry kernel interface" OFF)
+option( USE_OCC     "build with OpenCascade geometry kernel interface" ON)
 option( USE_STLGEOM     "build with STL geometry support" ON)
 option( USE_CSG     "build with CSG kernel" ON)
 option( USE_INTERFACE     "build nginterface" ON)

cmake/SuperBuild.cmake

@@ -121,7 +121,14 @@ else(BUILD_OCC)
           )
         list(APPEND NETGEN_DEPENDENCIES win_download_occ)
     else()
-        find_package(OpenCascade NAMES OpenCasCade OpenCASCADE opencascade REQUIRED)
+        find_package(OpenCascade NAMES OpenCasCade OpenCASCADE opencascade)
+        if(NOT OpenCascade_FOUND)
+          message(FATAL_ERROR "Opencascade not found, either\n\
+          - set OpenCascade_DIR to a directory containting opencascadeConfig.cmake\n\
+          - build OpenCascade automatically by passing -DBUILD_OCC=ON\n\
+          - disable OpenCascade by passing -DUSE_OCC=OFF\n\
+          ")
+        endif()
     endif()
 endif(BUILD_OCC)
 endif(USE_OCC)

tests/build_mpi.sh

@@ -5,6 +5,7 @@ cmake ../../src/netgen \
   -DCHECK_RANGE=ON \
   -DUSE_CCACHE=ON \
   -DUSE_MPI=ON \
+  -DUSE_OCC=OFF \
   -DENABLE_UNIT_TESTS=ON
 make -j12
 make install