Add Vulkan QML backend (#467)

This PR adds native Vulkan backend using Qt's QML Vulkan RHI.
This PR breaks ABI slightly, so it's best if it targets post-Garden.

With a few global variables we could workaround it and backport it to Garden though. Note that Garden supports Vulkan via a fallback that is very slow. This PR offers native, full speed integration.

Note: Qt 5.14 is the minimum requirement, which means it's not available on Ubuntu 20.04 but rather Ubuntu 22.04. I put macros to use at least 5.15.2 because that's what I tested against.

Note: Qt 5 considers Vulkan QML interface to be 'experimental' and I've submitted a patch to Qt to improve compliance with the Vulkan standard. Ideally Gazebo should eventually migrate to Qt 6.

Signed-off-by: Matias N. Goldberg <dark_sylinc@yahoo.com.ar>
Signed-off-by: Ian Chen <ichen@osrfoundation.org>
Co-authored-by: Ian Chen <ichen@osrfoundation.org>

include/gz/gui/Application.hh

@@ -70,8 +70,11 @@ namespace gz
  /// \param[in] _argc Argument count.
  /// \param[in] _argv Argument values.
  /// \param[in] _type Window type, by default it's a main window.
+ /// \param[in] _renderEngineGuiApiBackend --render-engine-gui-api-backend
+ /// option
  public: Application(int &_argc, char **_argv,
- const WindowType _type = WindowType::kMainWindow);
+ const WindowType _type = WindowType::kMainWindow,
+ const char *_renderEngineGuiApiBackend = nullptr);
 
  /// \brief Destructor
  public: virtual ~Application();

include/gz/gui/Helpers.hh

@@ -89,6 +89,15 @@ namespace gz
  GZ_GUI_VISIBLE
  std::string renderEngineName();
 
+ /// \brief Just like renderEngineName(), but valid entries are:
+ /// - opengl (default)
+ /// - metal (Apple only)
+ /// - vulkan
+ /// \return Name of API backend used on the GUI, as stored in the
+ /// `MainWindow`'s "renderEngineBackendApiName" property.
+ GZ_GUI_VISIBLE
+ std::string renderEngineBackendApiName();
+
  /// \brief Import path for gz-gui QML modules added to the Qt resource
  /// system. This helper function returns the QRC resource path where custom
  /// Gazebo QML modules can be imported from. To import a Gazebo QML

src/Application.cc

@@ -89,20 +89,48 @@ namespace gz
 using namespace gz;
 using namespace gui;
 
+enum class GZ_COMMON_HIDDEN AvailableAPIs
+{
+ OpenGL,
+ Vulkan,
+ Metal
+};
+
 /////////////////////////////////////////////////
-Application::Application(int &_argc, char **_argv, const WindowType _type)
- : QApplication(_argc, _argv), dataPtr(new ApplicationPrivate)
+Application::Application(int &_argc, char **_argv, const WindowType _type,
+ const char *_renderEngineGuiApiBackend) :
+ QApplication(_argc, _argv),
+ dataPtr(new ApplicationPrivate)
 {
  gzdbg << "Initializing application." << std::endl;
 
  this->setOrganizationName("Gazebo");
  this->setOrganizationDomain("gazebosim.org");
  this->setApplicationName("Gazebo GUI");
 
-#if __APPLE__
- // Use the Metal graphics API on macOS.
- gzdbg << "Qt using Metal graphics interface" << std::endl;
- QQuickWindow::setSceneGraphBackend(QSGRendererInterface::MetalRhi);
+#ifdef __APPLE__
+ AvailableAPIs api = AvailableAPIs::Metal;
+#else
+ AvailableAPIs api = AvailableAPIs::OpenGL;
+#endif
+ if (_renderEngineGuiApiBackend)
+ {
+ const std::string renderEngineGuiApiBackend = _renderEngineGuiApiBackend;
+ if (renderEngineGuiApiBackend == "vulkan")
+ api = AvailableAPIs::Vulkan;
+#ifdef __APPLE__
+ if (renderEngineGuiApiBackend == "metal")
+ api = AvailableAPIs::Metal;
+#endif
+ }
+
+#ifdef __APPLE__
+ if (api == AvailableAPIs::Metal)
+ {
+ // Use the Metal graphics API on macOS.
+ gzdbg << "Qt using Metal graphics interface" << std::endl;
+ QQuickWindow::setSceneGraphBackend(QSGRendererInterface::MetalRhi);
+ }
 
  // TODO(srmainwaring): implement facility for overriding the default
  // graphics API in macOS, in which case there are restrictions on
@@ -118,8 +146,32 @@ Application::Application(int &_argc, char **_argv, const WindowType _type)
  // format.setRenderableType(QSurfaceFormat::OpenGL);
  // QSurfaceFormat::setDefaultFormat(format);
 #else
- // Otherwise use OpenGL
- gzdbg << "Qt using OpenGL graphics interface" << std::endl;
+ // Otherwise use OpenGL (or Vulkan when supported and requested)
+
+ if (api == AvailableAPIs::Vulkan)
+ {
+ gzdbg << "Qt using Vulkan graphics interface" << std::endl;
+
+# ifdef GZ_USE_VULKAN_DEBUG_EXT
+ qputenv("QT_VULKAN_INSTANCE_EXTENSIONS",
+ "VK_EXT_debug_report;VK_EXT_debug_utils");
+# endif
+ qputenv("QT_VULKAN_DEVICE_EXTENSIONS",
+ "VK_KHR_maintenance2;VK_EXT_shader_subgroup_vote;"
+ "VK_EXT_shader_viewport_index_layer;"
+# ifdef GZ_USE_VULKAN_DEBUG_EXT
+ ";VK_EXT_debug_marker"
+# endif
+ );
+
+# if QT_VERSION >= QT_VERSION_CHECK(5, 15, 2) && QT_CONFIG(vulkan)
+ QQuickWindow::setSceneGraphBackend(QSGRendererInterface::VulkanRhi);
+# endif
+ }
+ else
+ {
+ gzdbg << "Qt using OpenGL graphics interface" << std::endl;
+ }
 #endif
 
  // Configure console
@@ -149,7 +201,28 @@ Application::Application(int &_argc, char **_argv, const WindowType _type)
  if (_type == WindowType::kMainWindow)
  {
  if (!this->InitializeMainWindow())
+ {
  gzerr << "Failed to initialize main window." << std::endl;
+ }
+ else
+ {
+ switch (api)
+ {
+ default:
+ case AvailableAPIs::OpenGL:
+ this->dataPtr->mainWin->setProperty("renderEngineBackendApiName",
+ "opengl");
+ break;
+ case AvailableAPIs::Vulkan:
+ this->dataPtr->mainWin->setProperty("renderEngineBackendApiName",
+ "vulkan");
+ break;
+ case AvailableAPIs::Metal:
+ this->dataPtr->mainWin->setProperty("renderEngineBackendApiName",
+ "metal");
+ break;
+ }
+ }
  }
  else if (_type == WindowType::kDialog)
  {

src/Helpers.cc

@@ -195,6 +195,20 @@ std::string gz::gui::renderEngineName()
  return renderEngineNameVariant.toString().toStdString();
 }
 
+/////////////////////////////////////////////////
+std::string gz::gui::renderEngineBackendApiName()
+{
+ auto win = App()->findChild<MainWindow *>();
+ if (nullptr == win)
+ return {};
+
+ auto renderEngineNameVariant = win->property("renderEngineBackendApiName");
+ if (!renderEngineNameVariant.isValid())
+ return {};
+
+ return renderEngineNameVariant.toString().toStdString();
+}
+
 /////////////////////////////////////////////////
 const QString gz::gui::qmlQrcImportPath()
 {

src/plugins/minimal_scene/CMakeLists.txt

@@ -2,6 +2,7 @@ set(SOURCES
  MinimalScene.cc
  MinimalSceneRhi.cc
  MinimalSceneRhiOpenGL.cc
+ MinimalSceneRhiVulkan.cc
  EngineToQtInterface.cc
 )