VR: Visibility mask support

Update osgXR to 0.3.3 which provides support for visibility masks using
the depth buffer, and extend VRManager to support them.

The following properties are added:
 - /sim/vr/openxr/extensions/visibility-mask: This exposes whether
   visibility masks are supported by the current OpenXR runtime, and
   maps to osgXR::Manager::hasVisibilityMaskExtension().
 - /sim/vr/visibility-mask: This allows visibility masks to be enabled
   and disabled, and maps to osgXR::Settings::setVisibilityMask() via a
   listener.

Finally we inform osgXR that it should use SimGear's newly defined
LEFT_BIT and RIGHT_BIT NodeMask bits for the visibility masks using
osgXR::Manager::setVisibilityMaskNodeMasks(). This allows a single
stereo camera to have a visibility mask for each eye.

CMakeLists.txt

@@ -152,7 +152,7 @@ elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux" OR
         set(SYSTEM_HTS_ENGINE_DEFAULT 1)
     endif()
 
-    find_package(osgXR 0.3)
+    find_package(osgXR 0.3.3)
     if (osgXR_FOUND)
         set(ENABLE_OSGXR_DEFAULT 1)
     endif()

src/Viewer/VRManager.cxx

@@ -20,6 +20,7 @@
 
 #include <osgXR/Settings>
 
+#include <simgear/scene/util/RenderConstants.hxx>
 #include <simgear/scene/viewer/CompositorPass.hxx>
 
 #include <Main/fg_props.hxx>
@@ -32,6 +33,7 @@ VRManager::VRManager() :
     _reloadCompositorCallback(new ReloadCompositorCallback(this)),
     _propXrLayersValidation("/sim/vr/openxr/layers/validation"),
     _propXrExtensionsDepthInfo("/sim/vr/openxr/extensions/depth-info"),
+    _propXrExtensionsVisibilityMask("/sim/vr/openxr/extensions/visibility-mask"),
     _propXrRuntimeName("/sim/vr/openxr/runtime/name"),
     _propXrSystemName("/sim/vr/openxr/system/name"),
     _propStateString("/sim/vr/state-string"),
@@ -39,6 +41,7 @@ VRManager::VRManager() :
     _propRunning("/sim/vr/running"),
     _propEnabled("/sim/vr/enabled"),
     _propDepthInfo("/sim/vr/depth-info"),
+    _propVisibilityMask("/sim/vr/visibility-mask"),
     _propValidationLayer("/sim/vr/validation-layer"),
     _propMode("/sim/vr/mode"),
     _propSwapchainMode("/sim/vr/swapchain-mode"),
@@ -46,6 +49,7 @@ VRManager::VRManager() :
     _propMirrorMode("/sim/vr/mirror-mode"),
     _listenerEnabled(this, &osgXR::Manager::setEnabled),
     _listenerDepthInfo(this, &VRManager::setDepthInfo),
+    _listenerVisibilityMask(this, &VRManager::setVisibilityMask),
     _listenerValidationLayer(this, &VRManager::setValidationLayer),
     _listenerMode(this, &VRManager::setVRMode),
     _listenerSwapchainMode(this, &VRManager::setSwapchainMode),
@@ -57,6 +61,10 @@ VRManager::VRManager() :
     _settings->setApp("FlightGear", fgVersion);
     _settings->preferEnvBlendMode(osgXR::Settings::OPAQUE);
 
+    // Inform osgXR what node masks to use
+    setVisibilityMaskNodeMasks(simgear::NodeMask::LEFT_BIT,
+                               simgear::NodeMask::RIGHT_BIT);
+
     // Hook into viewer, but don't enable VR just yet
     osgViewer::View *view = globals->get_renderer()->getView();
     if (view) {
@@ -68,6 +76,7 @@ VRManager::VRManager() :
 
     _propEnabled.node(true)->addChangeListener(&_listenerEnabled, true);
     _propDepthInfo.node(true)->addChangeListener(&_listenerDepthInfo, true);
+    _propVisibilityMask.node(true)->addChangeListener(&_listenerVisibilityMask, true);
     _propValidationLayer.node(true)->addChangeListener(&_listenerValidationLayer, true);
     _propMode.node(true)->addChangeListener(&_listenerMode, true);
     _propSwapchainMode.node(true)->addChangeListener(&_listenerSwapchainMode, true);
@@ -96,6 +105,7 @@ void VRManager::syncReadOnlyProperties()
 {
     _propXrLayersValidation = hasValidationLayer();
     _propXrExtensionsDepthInfo = hasDepthInfoExtension();
+    _propXrExtensionsVisibilityMask = hasVisibilityMaskExtension();
     _propXrRuntimeName = getRuntimeName();
     _propXrSystemName = getSystemName();
 
@@ -128,6 +138,12 @@ void VRManager::setDepthInfo(bool depthInfo)
     syncSettings();
 }
 
+void VRManager::setVisibilityMask(bool visibilityMask)
+{
+    _settings->setVisibilityMask(visibilityMask);
+    syncSettings();
+}
+
 void VRManager::setVRMode(const char * mode)
 {
     osgXR::Settings::VRMode vrMode = osgXR::Settings::VRMODE_AUTOMATIC;

src/Viewer/VRManager.hxx

@@ -78,6 +78,7 @@ class VRManager : public osgXR::Manager
 
         void setValidationLayer(bool validationLayer);
         void setDepthInfo(bool depthInfo);
+        void setVisibilityMask(bool visibilityMask);
 
         void setVRMode(const char * mode);
         void setSwapchainMode(const char * mode);
@@ -110,6 +111,7 @@ class VRManager : public osgXR::Manager
 
         SGPropObjBool _propXrLayersValidation;
         SGPropObjBool _propXrExtensionsDepthInfo;
+        SGPropObjBool _propXrExtensionsVisibilityMask;
         SGPropObjString _propXrRuntimeName;
         SGPropObjString _propXrSystemName;
 
@@ -119,6 +121,7 @@ class VRManager : public osgXR::Manager
 
         SGPropObjBool _propEnabled;
         SGPropObjBool _propDepthInfo;
+        SGPropObjBool _propVisibilityMask;
         SGPropObjBool _propValidationLayer;
         SGPropObjString _propMode;
         SGPropObjString _propSwapchainMode;
@@ -154,6 +157,7 @@ class VRManager : public osgXR::Manager
 
         ListenerBool _listenerEnabled;
         ListenerBool _listenerDepthInfo;
+        ListenerBool _listenerVisibilityMask;
         ListenerBool _listenerValidationLayer;
         ListenerString _listenerMode;
         ListenerString _listenerSwapchainMode;