From e25a5605910ee6c02e8c1f3c4ebc32aa8c681781 Mon Sep 17 00:00:00 2001
From: James Hogan <james@albanarts.com>
Date: Mon, 2 Aug 2021 23:38:56 +0100
Subject: [PATCH] CameraGroup: Add compositor reload callbacks

Add a compositor reload callback object to CameraInfo, with callbacks
for just prior and after the CameraInfo's compositor is reloaded by
reloadCompositors().

This will allow VR cameras to be reconfigured after a reload.
---
 src/Viewer/CameraGroup.cxx |  6 ++++++
 src/Viewer/CameraGroup.hxx | 11 ++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/Viewer/CameraGroup.cxx b/src/Viewer/CameraGroup.cxx
index a32ad3f15..e122b9c0e 100644
--- a/src/Viewer/CameraGroup.cxx
+++ b/src/Viewer/CameraGroup.cxx
@@ -982,6 +982,9 @@ void reloadCompositors(CameraGroup *cgroup)
             SGReaderWriterOptions::fromPath(globals->get_fg_root());
         options->setPropertyNode(globals->get_props());
 
+        if (info->reloadCompositorCallback.valid())
+            info->reloadCompositorCallback->preReloadCompositor(cgroup, info);
+
         // Force deletion
         info->compositor.reset(nullptr);
         // Then replace it with a new instance
@@ -993,6 +996,9 @@ void reloadCompositors(CameraGroup *cgroup)
                                                   viewport,
                                                   compositor_path,
                                                   options));
+
+        if (info->reloadCompositorCallback.valid())
+            info->reloadCompositorCallback->postReloadCompositor(cgroup, info);
     }
 
     cgroup->_viewer->getViewerBase()->startThreading();
diff --git a/src/Viewer/CameraGroup.hxx b/src/Viewer/CameraGroup.hxx
index 9ebcc570e..6e0bc58aa 100644
--- a/src/Viewer/CameraGroup.hxx
+++ b/src/Viewer/CameraGroup.hxx
@@ -51,6 +51,7 @@ namespace flightgear
 
 class CameraGroupListener;
 class GraphicsWindow;
+class CameraGroup;
 
 /** A wrapper around osg::Camera that contains some extra information.
  */
@@ -76,7 +77,7 @@ struct CameraInfo : public osg::Referenced
         flags(flags_),
         physicalWidth(0), physicalHeight(0), bezelHeightTop(0),
         bezelHeightBottom(0), bezelWidthLeft(0), bezelWidthRight(0),
-        relativeCameraParent(0) { }
+        relativeCameraParent(0), reloadCompositorCallback(nullptr) { }
     /** The name as given in the config file.
      */
     std::string name;
@@ -120,6 +121,14 @@ struct CameraInfo : public osg::Referenced
      * Compositor path and should use the default one.
      */
     std::string compositor_path;
+
+    struct ReloadCompositorCallback : public virtual osg::Referenced
+    {
+        virtual void preReloadCompositor(CameraGroup *, CameraInfo *) = 0;
+        virtual void postReloadCompositor(CameraGroup *, CameraInfo *) = 0;
+    };
+    osg::ref_ptr<ReloadCompositorCallback> reloadCompositorCallback;
+
 };
 
 class CameraGroup : public osg::Referenced