EGL headless visualization

.github/workflows/builds.yml

@@ -135,7 +135,7 @@ jobs:
       uses: actions/cache@v4
       with:
         path: ${{ env.MFEM_TOP_DIR }}
-        key: ${{ runner.os }}-build-${{ env.MFEM_TOP_DIR }}-${{ env.MFEM_COMMIT }}-${{ matrix.target }}-${{ matrix.build-system}}-v2.4
+        key: ${{ runner.os }}-build-${{ env.MFEM_TOP_DIR }}-${{ env.MFEM_COMMIT }}-${{ matrix.build-system }}-${{ matrix.target }}-${{ matrix.mpi }}-v2.4
 
     # We are using the defaults of the MFEM action here, which is to use master
     # branch. There is an implicit assumption here that mfem master hasn't
@@ -199,7 +199,11 @@ jobs:
       run: |
         glvis_target="opt"
         [[ ${{ matrix.target }} == "dbg" ]] && glvis_target="debug";
-        cd glvis && make ${glvis_target} -j3
+        use_egl="NO"
+        [[ ${{ matrix.os }} == "ubuntu-latest" ]] && use_egl="YES"
+        use_cgl="NO"
+        [[ ${{ matrix.os }} == "macos-latest" ]] && use_cgl="YES"
+        cd glvis && make ${glvis_target} -j3 GLVIS_USE_EGL=${use_egl} GLVIS_USE_CGL=${use_cgl}
 
     - name: build GLVis (cmake)
       if: matrix.build-system == 'cmake'
@@ -210,11 +214,17 @@ jobs:
         [[ ${{ matrix.target }} == "dbg" ]] && build_type="Debug";
         [[ ${{ matrix.os }} == "windows-latest" ]] \
           && toolchain_file="${VCPKG_INSTALLATION_ROOT}\\scripts\\buildsystems\\vcpkg.cmake"
+        use_egl="OFF"
+        [[ ${{ matrix.os }} == "ubuntu-latest" ]] && use_egl="ON"
+        use_cgl="NO"
+        [[ ${{ matrix.os }} == "macos-latest" ]] && use_cgl="YES"
         cd glvis && mkdir build && cd build
         cmake \
           -D CMAKE_TOOLCHAIN_FILE:STRING=${toolchain_file} \
           -D CMAKE_BUILD_TYPE:STRING=${build_type} \
           -D ENABLE_TESTS:BOOL=TRUE \
+          -D GLVIS_USE_EGL:BOOL=${use_egl} \
+          -D GLVIS_USE_CGL:BOOL=${use_cgl} \
           -D mfem_DIR:PATH=${GITHUB_WORKSPACE}/${MFEM_TOP_DIR}/build \
           -D GLVIS_BASELINE_SYS=${{ matrix.os }} \
           ..

.github/workflows/release.yml

@@ -118,7 +118,7 @@ jobs:
       uses: actions/cache@v4
       with:
         path: ${{ env.MFEM_TOP_DIR }}
-        key: ${{ runner.os }}-build-${{ env.MFEM_TOP_DIR }}-${{ env.MFEM_COMMIT }}-${{ matrix.target }}-${{ matrix.build-system}}-v2.2
+        key: ${{ runner.os }}-build-${{ env.MFEM_TOP_DIR }}-${{ env.MFEM_COMMIT }}-${{ matrix.build-system }}-${{ matrix.target }}-${{ matrix.mpi }}-v2.2
 
     # We are using the defaults of the MFEM action here, which is to use master
     # branch. There is an implicit assumption here that mfem master hasn't

CHANGELOG

@@ -14,6 +14,15 @@ Version 4.4.1 (development)
 
 Unlike previous GLVis releases, this version requires a C++17 compiler.
 
+- Added headless (no GUI) visualization, relying on the EGL (Linux) or CGL
+  (MacOS) interface. It is available through '-hl' command-line option or
+  'headless' script command (before the visualization commands). The end of the
+  loaded stream or script file ends the visualization in this mode. Note GLVis
+  must be compiled with with EGL/CGL (see INSTALL).
+
+- Added non-persistent mode of the server, when the server terminates after all
+  visualization windows are closed.
+
 - Implemented DOF numbering in 2D scalar mode, pressing the `n` or `N` key cycles
   through: None → Elements → Edges → Vertices → DOFs. Parallel numbering is now by
   default 'local' to each rank; 'global' vs. 'local' numbering can be toggled with

CMakeLists.txt

@@ -68,6 +68,14 @@ option(GLVIS_USE_LIBPNG
   "Use libpng for taking screenshots internally"
   ON)
 
+option(GLVIS_USE_EGL
+  "Use EGL for headless rendering"
+  OFF)
+
+option(GLVIS_USE_CGL
+  "Use CGL for headless rendering"
+  APPLE)
+
 #
 # Handle a few other definitions
 #
@@ -237,6 +245,23 @@ if (NOT EMSCRIPTEN)
     message(FATAL_ERROR "Fontconfig not found.")
   endif (FONTCONFIG_LIBRARY)
 
+  # Find EGL
+  if (GLVIS_USE_EGL)
+    find_package(OpenGL OPTIONAL_COMPONENTS EGL)
+    if (OpenGL_EGL_FOUND)
+      list(APPEND _glvis_compile_defs "GLVIS_USE_EGL")
+      list(APPEND _glvis_libraries OpenGL::EGL)
+    else()
+      message(WARNING "EGL library not found. EGL disabled.")
+      set(GLVIS_USE_EGL OFF)
+    endif (OpenGL_EGL_FOUND)
+  endif (GLVIS_USE_EGL)
+
+  # Find CGL
+  if (GLVIS_USE_CGL)
+    list(APPEND _glvis_compile_defs "GLVIS_USE_CGL")
+  endif (GLVIS_USE_CGL)
+
   # Find threading library
   find_package(Threads REQUIRED)
   list(APPEND _glvis_libraries "${CMAKE_THREAD_LIBS_INIT}")

INSTALL

@@ -38,6 +38,9 @@ Besides a C++ compiler, GLVis depends on the following external packages:
 - the XQuartz app (on Mac OS X, if running GLVis remotely through ssh)
   https://www.xquartz.org
 
+- the EGL library; used for headless rendering (optional)
+  https://www.khronos.org/egl
+
 There are two build systems, one based on GNU make and one based on CMake, as
 described below. Choose the one that matches the build system you used to
 build MFEM.
@@ -87,6 +90,7 @@ cmake \
     \
     -D GLVIS_USE_LIBTIFF=OFF \
     -D GLVIS_USE_LIBPNG=ON \
+    -D GLVIS_USE_EGL=OFF \
     \
     -D MFEM_DIR=/path/to/directory/with/MFEMConfig.cmake \
     \
@@ -111,6 +115,11 @@ Some important variables for CMake are:
 
 - GLVIS_USE_LIBTIFF: Use libtiff for creating screenshots. Default is "OFF".
 
+- GLVIS_USE_EGL: Use EGL for headless rendering. Default is "OFF".
+
+- GLVIS_USE_CGL: Use CGL for headless rendering on Mac OS X. Default is "ON" on
+     this platform, "OFF" otherwise.
+
 - GLVIS_MULTISAMPLE and GLVIS_MS_LINEWIDTH: See building considerations below
      for more information on these variables.
 

glvis.cpp

@@ -42,6 +42,8 @@
 #include "lib/stream_reader.hpp"
 #include "lib/file_reader.hpp"
 #include "lib/coll_reader.hpp"
+#include "lib/sdl/sdl.hpp"
+#include "lib/egl/egl.hpp"
 
 using namespace std;
 using namespace mfem;
@@ -77,11 +79,13 @@ class Session
 public:
    Session(bool fix_elem_orient,
            bool save_coloring,
-           string plot_caption)
+           string plot_caption,
+           bool headless)
    {
       win.data_state.fix_elem_orient = fix_elem_orient;
       win.data_state.save_coloring = save_coloring;
       win.plot_caption = plot_caption;
+      win.headless = headless;
    }
 
    Session(Window other_win)
@@ -154,7 +158,7 @@ class Session
 };
 
 void GLVisServer(int portnum, bool save_stream, bool fix_elem_orient,
-                 bool save_coloring, string plot_caption)
+                 bool save_coloring, string plot_caption, bool headless = false)
 {
    std::vector<Session> current_sessions;
    string data_type;
@@ -304,7 +308,7 @@ void GLVisServer(int portnum, bool save_stream, bool fix_elem_orient,
          while (1);
       }
 
-      Session new_session(fix_elem_orient, save_coloring, plot_caption);
+      Session new_session(fix_elem_orient, save_coloring, plot_caption, headless);
 
       constexpr int tmp_filename_size = 50;
       char tmp_file[tmp_filename_size];
@@ -381,6 +385,7 @@ int main (int argc, char *argv[])
    const char *window_title  = string_default;
    const char *font_name     = string_default;
    int         portnum       = 19916;
+   bool        persistent    = true;
    int         multisample   = GetMultisample();
    double      line_width    = GetLineWidth();
    double      ms_line_width = GetLineWidthMS();
@@ -451,6 +456,9 @@ int main (int argc, char *argv[])
                   "Save the mesh coloring generated when opening only a mesh.");
    args.AddOption(&portnum, "-p", "--listen-port",
                   "Specify the port number on which to accept connections.");
+   args.AddOption(&persistent, "-pr", "--persistent",
+                  "-no-pr", "--no-persistent",
+                  "Keep server running after all windows are closed.");
    args.AddOption(&secure, "-sec", "--secure-sockets",
                   "-no-sec", "--standard-sockets",
                   "Enable or disable GnuTLS secure sockets.");
@@ -466,6 +474,9 @@ int main (int argc, char *argv[])
                   "Set the window height.");
    args.AddOption(&window_title, "-wt", "--window-title",
                   "Set the window title.");
+   args.AddOption(&win.headless, "-hl", "--headless",
+                  "-no-hl", "--no-headless",
+                  "Start headless (no GUI) visualization.");
    args.AddOption(&c_plot_caption, "-c", "--plot-caption",
                   "Set the plot caption (visible when colorbar is visible).");
    args.AddOption(&font_name, "-fn", "--font",
@@ -607,20 +618,21 @@ int main (int argc, char *argv[])
    // check for saved stream file
    if (stream_file != string_none)
    {
+      // backup the headless flag as the window is moved
+      const bool headless = win.headless;
+
       // Make sure the singleton object returned by GetMainThread() is
       // initialized from the main thread.
-      GetMainThread();
+      GetMainThread(headless);
 
-      Session stream_session(win.data_state.fix_elem_orient,
-                             win.data_state.save_coloring,
-                             win.plot_caption);
+      Session stream_session(std::move(win));
 
       if (!stream_session.StartSavedSession(stream_file))
       {
          return 1;
       }
 
-      SDLMainLoop();
+      MainThreadLoop(headless);
       return 0;
    }
 
@@ -676,17 +688,16 @@ int main (int argc, char *argv[])
    {
       // Make sure the singleton object returned by GetMainThread() is
       // initialized from the main thread.
-      GetMainThread();
+      GetMainThread(win.headless);
 
       // Run server in new thread
       std::thread serverThread{GLVisServer, portnum, save_stream,
                                win.data_state.fix_elem_orient,
                                win.data_state.save_coloring,
-                               win.plot_caption};
-
-      // Start SDL in main thread
-      SDLMainLoop(true);
+                               win.plot_caption, win.headless};
 
+      // Start message loop in main thread
+      MainThreadLoop(win.headless, persistent);
       serverThread.detach();
    }
    else  // input != 1, non-server mode
@@ -792,14 +803,17 @@ int main (int argc, char *argv[])
          if (ierr) { exit(ierr); }
       }
 
+      // backup the headless flag as the window is moved
+      const bool headless = win.headless;
+
       // Make sure the singleton object returned by GetMainThread() is
       // initialized from the main thread.
-      GetMainThread();
+      GetMainThread(headless);
 
       Session single_session(std::move(win));
       single_session.StartSession();
 
-      SDLMainLoop();
+      MainThreadLoop(headless);
    }
 
    cout << "Thank you for using GLVis." << endl;

lib/CMakeLists.txt

@@ -10,25 +10,28 @@
 # CONTRIBUTING.md for details.
 
 list(APPEND SOURCES
+  egl/egl.cpp
+  egl/egl_main.cpp
   gl/renderer.cpp
   gl/renderer_core.cpp
   gl/shader.cpp
   gl/types.cpp
+  sdl/sdl.cpp
+  sdl/sdl_helper.cpp
+  sdl/sdl_main.cpp
   aux_vis.cpp
   coll_reader.cpp
   data_state.cpp
   file_reader.cpp
   font.cpp
   gltf.cpp
+  glwindow.cpp
   material.cpp
   openglvis.cpp
   palettes.cpp
   palettes_default.cpp
   palettes_base.cpp
   script_controller.cpp
-  sdl.cpp
-  sdl_helper.cpp
-  sdl_main.cpp
   stream_reader.cpp
   vsdata.cpp
   vssolution.cpp
@@ -38,29 +41,32 @@ list(APPEND SOURCES
   window.cpp)
 
 list(APPEND HEADERS
+  egl/egl.hpp
+  egl/egl_main.hpp
   gl/attr_traits.hpp
   gl/platform_gl.hpp
   gl/renderer.hpp
   gl/renderer_core.hpp
   gl/shader.hpp
   gl/types.hpp
+  sdl/sdl.hpp
+  sdl/sdl_helper.hpp
+  sdl/sdl_main.hpp
+  sdl/sdl_mac.hpp
   aux_vis.hpp
   coll_reader.hpp
   data_state.hpp
   file_reader.hpp
   font.hpp
   geom_utils.hpp
   gltf.hpp
+  glwindow.hpp
   logo.hpp
   material.hpp
   openglvis.hpp
   palettes.hpp
   palettes_base.hpp
   script_controller.hpp
-  sdl.hpp
-  sdl_helper.hpp
-  sdl_main.hpp
-  sdl_mac.hpp
   stream_reader.hpp
   visual.hpp
   vsdata.hpp
@@ -89,15 +95,15 @@ if(EMSCRIPTEN)
   target_link_libraries(libglvis PUBLIC "${_glvis_libraries}")
 else()
   # Desktop build target
-  list(APPEND SOURCES gl/renderer_ff.cpp threads.cpp gl2ps.c sdl_x11.cpp)
-  list(APPEND HEADERS gl/renderer_ff.hpp threads.hpp gl2ps.h sdl_x11.hpp)
+  list(APPEND SOURCES gl/renderer_ff.cpp threads.cpp gl2ps.c sdl/sdl_x11.cpp)
+  list(APPEND HEADERS gl/renderer_ff.hpp threads.hpp gl2ps.h sdl/sdl_x11.hpp)
   if (APPLE)
-    list(APPEND SOURCES sdl_mac.mm)
-    list(APPEND HEADERS sdl_mac.hpp)
+    list(APPEND SOURCES sdl/sdl_mac.mm)
+    list(APPEND HEADERS sdl/sdl_mac.hpp)
   endif()
   if (WIN32)
-    list(APPEND SOURCES sdl_windows.cpp)
-    list(APPEND HEADERS sdl_windows.hpp)
+    list(APPEND SOURCES sdl/sdl_windows.cpp)
+    list(APPEND HEADERS sdl/sdl_windows.hpp)
   endif()
   add_library(glvis ${SOURCES} ${HEADERS})
   target_compile_definitions(glvis PUBLIC "${_glvis_compile_defs}")