0022795: Make possible to display some presentable objects in overlay of others, groupped by display priority

src/AIS/AIS_InteractiveContext.cxx

@@ -3194,7 +3194,13 @@ Standard_Integer AIS_InteractiveContext::GetZLayer (const Handle(AIS_Interactive
     return -1;
 
   if (myObjects.IsBound (theIObj))
+  {
     return theIObj->GetZLayer (myMainPM);
-
+  }
+  else if (HasOpenedContext ())
+  {
     return myLocalContexts (myCurLocalIndex)->GetZLayer (theIObj);
   }
+
+  return -1;
+}

src/Visual3d/Visual3d_View.cxx

@@ -509,6 +509,9 @@ const Handle(WNT_Window) theWindow = *(Handle(WNT_Window) *) &AWindow;
         MyGraphicDriver->ClipLimit (MyCView, AWait);
         MyGraphicDriver->Environment(MyCView);
 
+        // Make view manager z layer list consistent with the view's list.
+        MyViewManager->InstallZLayers (this);
+
         // Update planses of model clipping
         UpdatePlanes ();
 

src/Visual3d/Visual3d_ViewManager.cdl

@@ -302,6 +302,13 @@ is
         -- from lowest layer to highest ( foreground ). The first layer ID
         -- in sequence is the default layer that can't be removed.
 
+        InstallZLayers ( me;
+                         theView : View from Visual3d )
+           is private;
+        ---Purpose: Install z layers managed by the view manager into the
+        -- controlled view. This method used on the view initialization to
+        -- make the layer lists consistent.
+
         getZLayerGenId ( myclass )
         ---Purpose: Returns global instance of z layer ids generator.
         ---C++: return &

src/Visual3d/Visual3d_ViewManager.cxx

@@ -1248,3 +1248,26 @@ Aspect_GenId& Visual3d_ViewManager::getZLayerGenId ()
   static Aspect_GenId aGenId (1, IntegerLast());
   return aGenId;
 }
+
+//=======================================================================
+//function : InstallZLayers
+//purpose  :
+//=======================================================================
+
+void Visual3d_ViewManager::InstallZLayers(const Handle(Visual3d_View)& theView) const
+{
+  if (!MyDefinedView.Contains (theView))
+    return;
+  
+  // erase and insert layers iteratively to provide the same layer order as
+  // in the view manager's sequence. This approach bases on the layer insertion
+  // order: the new layers are always appended to the end of the list
+  // inside of view, while layer remove operation doesn't affect the order.
+  // Starting from second layer : no need to change the default z layer.
+  for (Standard_Integer aSeqIdx = 2; aSeqIdx <= myLayerSeq.Length (); aSeqIdx++)
+  {
+    Standard_Integer aLayerID = myLayerSeq.Value (aSeqIdx);
+    theView->RemoveZLayer (aLayerID);
+    theView->AddZLayer (aLayerID);
+  }
+}