graphics: add support for swiftshader based software rendering

snap/snapcraft.yaml

@@ -128,6 +128,23 @@ parts:
       - bin/lxc-ls
       - bin/lxc-top
 
+  swiftshader:
+    plugin: cmake
+    source: https://github.com/google/swiftshader.git
+    source-type: git
+    source-commit: cbb80f5f0078a9941f3ec43e83e52c3d15a43bea
+    override-build: |
+      git submodule update --init
+      snapcraftctl build
+    artifacts:
+      - libEGL.so
+      - libGLES_CM.so
+      - libGLESv2.so
+    organize:
+      libEGL.so: lib/anbox/swiftshader/libEGL.so
+      libGLES_CM.so: lib/anbox/swiftshader/libGLES_CM.so
+      libGLESv2.so: lib/anbox/swiftshader/libGLESv2.so
+
   anbox-scripts:
     plugin: dump
     source: scripts

src/anbox/cmds/session_manager.cpp

@@ -109,6 +109,9 @@ anbox::cmds::SessionManager::SessionManager()
   flag(cli::make_flag(cli::Name{"use-system-dbus"},
                       cli::Description{"Use system instead of session DBus"},
                       use_system_dbus_));
+  flag(cli::make_flag(cli::Name{"software-rendering"},
+                      cli::Description{"Use software rendering instead of hardware accelerated GL rendering"},
+                      use_software_rendering_));
 
   action([this](const cli::Command::Context &) {
     auto trap = core::posix::trap_signals_for_process(
@@ -169,8 +172,12 @@ anbox::cmds::SessionManager::SessionManager()
       using_single_window = true;
     }
 
+    auto gl_driver = graphics::GLRendererServer::Config::Driver::Host;
+    if (use_software_rendering_)
+     gl_driver = graphics::GLRendererServer::Config::Driver::Software;
+
     graphics::GLRendererServer::Config renderer_config {
-      graphics::GLRendererServer::Config::Driver::Host,
+      gl_driver,
       single_window_
     };
     auto gl_server = std::make_shared<graphics::GLRendererServer>(renderer_config, window_manager);

src/anbox/cmds/session_manager.h

@@ -49,6 +49,7 @@ class SessionManager : public cli::CommandWithFlagsAndAction {
   bool standalone_ = false;
   bool experimental_ = false;
   bool use_system_dbus_ = false;
+  bool use_software_rendering_ = false;
 };
 }  // namespace cmds
 }  // namespace anbox

src/anbox/graphics/gl_renderer_server.cpp

@@ -30,6 +30,8 @@
 #include <cstdarg>
 #include <stdexcept>
 
+namespace fs = boost::filesystem;
+
 namespace {
 void logger_write(const emugl::LogLevel &level, const char *format, ...) {
   (void)level;
@@ -77,6 +79,18 @@ GLRendererServer::GLRendererServer(const Config &config, const std::shared_ptr<w
   composer_ = std::make_shared<LayerComposer>(renderer_, composer_strategy);
 
   auto gl_libs = emugl::default_gl_libraries();
+  if (config.driver == Config::Driver::Software) {
+    const auto snap_path = utils::get_env_value("SNAP");
+    if (snap_path.empty())
+      throw std::runtime_error("Software rendering is not available outside of a snap build");
+
+    auto swiftshader_path = fs::path(snap_path) / "lib" / "anbox" / "swiftshader";
+    gl_libs = std::vector<emugl::GLLibrary>{
+      {emugl::GLLibrary::Type::EGL, (swiftshader_path / "libEGL.so").string()},
+      {emugl::GLLibrary::Type::GLESv1, (swiftshader_path / "libGLES_CM.so").string()},
+      {emugl::GLLibrary::Type::GLESv2, (swiftshader_path / "libGLESv2.so").string()},
+    };
+  }
 
   emugl_logger_struct log_funcs;
   log_funcs.coarse = logger_write;

src/anbox/graphics/gl_renderer_server.h

@@ -35,7 +35,14 @@ class LayerComposer;
 class GLRendererServer {
  public:
   struct Config {
-    enum class Driver { Host };
+    enum class Driver {
+      // Use the GL driver provided by the host operating system
+      Host,
+
+      // Use a builtin software based GL driver implementation without any support
+      // for hardware acceleration.
+      Software,
+    };
     Driver driver;
     bool single_window;
   };