Globals: Initial support for a runtime headless mode.

src/Main/globals.cxx

@@ -161,7 +161,8 @@ FGGlobals::FGGlobals() :
     channel_options_list( NULL ),
     initial_waypoints( NULL ),
     channellist( NULL ),
-    haveUserSettings(false)
+    haveUserSettings(false),
+    _headless(false)
 {
     SGPropertyNode* root = new SGPropertyNode;
     props = SGPropertyNode_ptr(root);
@@ -923,4 +924,14 @@ void FGGlobals::setPackageRoot(const SGSharedPtr<simgear::pkg::Root>& p)
   _packageRoot = p;
 }
 
+bool FGGlobals::is_headless()
+{
+    return _headless;
+}
+
+void FGGlobals::set_headless(bool mode)
+{
+    _headless = mode;
+}
+
 // end of globals.cxx

src/Main/globals.hxx

@@ -156,6 +156,9 @@ private:
     SGPropertyChangeListenerVec _listeners_to_cleanup;
 
     SGSharedPtr<simgear::pkg::Root> _packageRoot;
+
+    bool _headless;
+
 public:
 
     FGGlobals();
@@ -404,6 +407,12 @@ public:
 
     simgear::pkg::Root* packageRoot();
     void setPackageRoot(const SGSharedPtr<simgear::pkg::Root>& p);
+
+    /**
+     * A runtime headless mode for running without a GUI.
+     */
+    bool is_headless();
+    void set_headless(bool mode);
 };