Untangle osg singleton dependencies.

Take two. The ModelRegistry's are already derived from osg::Referenced.
So also introduce the osg dependent version in simgear/scene/util.

CMakeLists.txt

@@ -115,7 +115,6 @@ find_package(Threads REQUIRED)
 
 if(SIMGEAR_HEADLESS)
     message(STATUS "headless mode")
-    set(NO_OPENSCENEGRAPH_INTERFACE 1)
 else()
     find_package(OpenGL REQUIRED)
     find_package(OpenAL REQUIRED)

simgear/CMakeLists.txt

@@ -46,7 +46,6 @@ if(SIMGEAR_SHARED)
     get_property(publicHeaders GLOBAL PROPERTY PUBLIC_HEADERS)
 
     add_library(SimGearCore SHARED ${coreSources})
-    set_property(TARGET SimGearCore PROPERTY COMPILE_FLAGS "-DNO_OPENSCENEGRAPH_INTERFACE=1")
 
   # set_property(TARGET SimGearCore PROPERTY FRAMEWORK 1)
   #  message(STATUS "public header: ${publicHeaders}")

simgear/scene/model/ModelRegistry.hxx

@@ -27,7 +27,7 @@
 #include <osgDB/Registry>
 
 #include <simgear/compiler.h>
-#include <simgear/structure/Singleton.hxx>
+#include <simgear/scene/util/OsgSingleton.hxx>
 
 #include <string>
 #include <map>

simgear/scene/tgdb/GroundLightManager.hxx

@@ -24,7 +24,7 @@
 #include <osg/StateSet>
 
 
-#include <simgear/structure/Singleton.hxx>
+#include <simgear/scene/util/OsgSingleton.hxx>
 #include <simgear/scene/util/SGUpdateVisitor.hxx>
 
 namespace simgear

simgear/scene/util/CMakeLists.txt

@@ -4,6 +4,7 @@ set(HEADERS
     CopyOp.hxx
     NodeAndDrawableVisitor.hxx
     OsgMath.hxx
+    OsgSingleton.hxx
     PrimitiveUtils.hxx
     QuadTreeBuilder.hxx
     RenderConstants.hxx

simgear/scene/util/OsgSingleton.hxx

@@ -0,0 +1,41 @@
+#ifndef SIMGEAR_OSGSINGLETON_HXX
+#define SIMGEAR_OSGSINGLETON_HXX 1
+
+#include <simgear/structure/Singleton.hxx>
+
+#include <osg/Referenced>
+#include <osg/ref_ptr>
+
+namespace simgear {
+
+template <typename RefClass>
+class SingletonRefPtr
+{
+public:
+    SingletonRefPtr()
+    {
+        ptr = new RefClass;
+    }
+    static RefClass* instance()
+    {
+        SingletonRefPtr& singleton
+            = boost::details::pool::singleton_default<SingletonRefPtr>::instance();
+        return singleton.ptr.get();
+    }
+private:
+    osg::ref_ptr<RefClass> ptr;
+};
+
+template <typename RefClass>
+class ReferencedSingleton : public virtual osg::Referenced
+{
+public:
+    static RefClass* instance()
+    {
+        return SingletonRefPtr<RefClass>::instance();
+    }
+};
+
+}
+
+#endif

simgear/scene/util/StateAttributeFactory.hxx

@@ -37,7 +37,7 @@ class Texture2D;
 class TexEnv;
 }
 
-#include <simgear/structure/Singleton.hxx>
+#include <simgear/scene/util/OsgSingleton.hxx>
 
 // Return read-only instances of common OSG state attributes.
 namespace simgear

simgear/simgear_config_cmake.h.in

@@ -17,6 +17,3 @@
 #cmakedefine HAVE_LIBSVN_CLIENT_1
 
 #cmakedefine GCC_ATOMIC_BUILTINS_FOUND
-
-// set if building headless (no OSG or OpenGL libs)
-#cmakedefine NO_OPENSCENEGRAPH_INTERFACE

simgear/structure/Singleton.hxx

@@ -3,11 +3,6 @@
 
 #include "singleton.hpp"
 
-#ifndef NO_OPENSCENEGRAPH_INTERFACE
-#include <osg/Referenced>
-#include <osg/ref_ptr>
-#endif
-
 namespace simgear
 {
 /**
@@ -29,35 +24,5 @@ public:
     }
 };
 
-#ifndef NO_OPENSCENEGRAPH_INTERFACE
-template <typename RefClass>
-class SingletonRefPtr
-{
-public:
-    SingletonRefPtr()
-    {
-        ptr = new RefClass;
-    }
-    static RefClass* instance()
-    {
-        SingletonRefPtr& singleton
-            = boost::details::pool::singleton_default<SingletonRefPtr>::instance();
-        return singleton.ptr.get();
-    }
-private:
-    osg::ref_ptr<RefClass> ptr;
-};
-
-template <typename RefClass>
-class ReferencedSingleton : public virtual osg::Referenced
-{
-public:
-    static RefClass* instance()
-    {
-        return SingletonRefPtr<RefClass>::instance();
-    }
-};
-#endif // of NO_OPENSCENEGRAPH_INTERFACE
-
 }
 #endif