[Metal] Add Metal support for macOS

Update ign command script
- Remove server only setting for macOS

Enable the sensors server plugin to run on macOS
- Initialise the render engine for sensors on the main thread
- Platform specific OpenGL context code must be moved elsewhere.
- Ensure the active OpenGL context is associated with the render thread post initialisation

Enable the Gazebo GUI to run on macOS
- Move the RenderThread object to the render thread at the same time as a the OpenGL context

Reinstate render synchronisation
- Reinstate Ignition / QML serial rendering IgnRenderer::Render.
- Allow IgnRenderer::Render to accept a nullptr so it can be called without render sync from the main thread before the render thread is started.

Update QML
- Add missing properties for tooltopDelay

Configure the Qt scene graph to use the Metal backend
- Force the gazebo application to use the Metal backend for the Qt scene graph
- Move Metal scene graph backend to ign::gui::Application

Modify sensors to use Metal
- Set the render system parameter to use Metal

Default to Metal on macOS, otherwise use OpenGL
- Add preprocessor checks to use the Metal graphics API for __APPLE__

Signed-off-by: Rhys Mainwaring <rhys.mainwaring@me.com>

src/cmd/cmdgazebo.rb.in

@@ -446,13 +446,6 @@ has properly set the DYLD_LIBRARY_PATH environment variables."
       # Neither the -s nor -g options were used, so run both the server
       # and gui.
       if options['server'] == 0 && options['gui'] == 0
-
-        if plugin.end_with? ".dylib"
-          puts "`ign gazebo` currently only works with the -s argument on macOS.
-See https://github.com/ignitionrobotics/ign-gazebo/issues/44 for more info."
-          exit(-1)
-        end
-
         serverPid = Process.fork do
           ENV['RMT_PORT'] = '1500'
           Process.setpgid(0, 0)
@@ -504,12 +497,6 @@ See https://github.com/ignitionrobotics/ign-gazebo/issues/44 for more info."
             options['headless-rendering'])
       # Otherwise run the gui
       else options['gui']
-        if plugin.end_with? ".dylib"
-          puts "`ign gazebo` currently only works with the -s argument on macOS.
-See https://github.com/ignitionrobotics/ign-gazebo/issues/44 for more info."
-          exit(-1)
-        end
-
         ENV['RMT_PORT'] = '1501'
         Importer.runGui(options['gui_config'], options['render_engine_gui'])
       end

src/gui/plugins/component_inspector/Boolean.qml

@@ -34,6 +34,8 @@ Rectangle {
   // Horizontal margins
   property int margin: 5
 
+  property int tooltipDelay: 500
+
   RowLayout {
     anchors.fill: parent
 

src/gui/plugins/modules/TypeIcon.qml

@@ -31,6 +31,8 @@ Image {
    */
   property string entityType: ''
 
+  property int tooltipDelay: 500
+
   /**
    * Image address according to type
    */

src/gui/plugins/visualize_lidar/VisualizeLidar.qml

@@ -30,6 +30,9 @@ GridLayout {
   anchors.leftMargin: 10
   anchors.rightMargin: 10
 
+  property int tooltipDelay: 500
+  property int tooltipTimeout: 1000
+
   CheckBox {
     Layout.alignment: Qt.AlignHCenter
     id: displayVisual

src/rendering/RenderUtil.cc

@@ -2536,11 +2536,20 @@ void RenderUtil::Init()
   rendering::setPluginPaths(pluginPath.PluginPaths());
 
   std::map<std::string, std::string> params;
+#ifdef __APPLE__
+  // TODO(srmainwaring): implement facility for overriding the default
+  //    graphics API in macOS, in which case there are restrictions on
+  //    the version of OpenGL used.
+  params["metal"] = "1";
+#else
   if (this->dataPtr->useCurrentGLContext)
     params["useCurrentGLContext"] = "1";
+#endif
+
   if (this->dataPtr->isHeadlessRendering)
     params["headless"] = "1";
   params["winID"] = this->dataPtr->winID;
+
   this->dataPtr->engine = rendering::engine(this->dataPtr->engineName, params);
   if (!this->dataPtr->engine)
   {

src/systems/sensors/Sensors.cc

@@ -210,7 +210,7 @@ void SensorsPrivate::WaitForInit()
         this->renderUtil.SetBackgroundColor(*this->backgroundColor);
       if (this->ambientLight)
         this->renderUtil.SetAmbientLight(*this->ambientLight);
-      this->renderUtil.Init();
+
       this->scene = this->renderUtil.Scene();
       this->scene->SetCameraPassCountPerGpuFlush(6u);
       this->initialized = true;
@@ -461,7 +461,21 @@ void Sensors::Update(const UpdateInfo &_info,
                      EntityComponentManager &_ecm)
 {
   IGN_PROFILE("Sensors::Update");
-  std::unique_lock<std::mutex> lock(this->dataPtr->renderMutex);
+
+  if (!this->dataPtr->initialized &&
+      (_ecm.HasComponentType(components::Camera::typeId) ||
+       _ecm.HasComponentType(components::DepthCamera::typeId) ||
+       _ecm.HasComponentType(components::GpuLidar::typeId) ||
+       _ecm.HasComponentType(components::RgbdCamera::typeId) ||
+       _ecm.HasComponentType(components::ThermalCamera::typeId)))
+  {
+    igndbg << "Initialization needed" << std::endl;
+    std::unique_lock<std::mutex> lock(this->dataPtr->renderMutex);
+
+    // Initialise render engine on main thread
+    this->dataPtr->renderUtil.Init();
+  }
+
   if (this->dataPtr->running && this->dataPtr->initialized)
   {
     this->dataPtr->renderUtil.UpdateECM(_info, _ecm);