Add support for runtime fall-back from o3d to o2d.

core/cross/renderer.h

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 129 matching lines @@
 
    private:
     int index_;
   };
 
   virtual ~Renderer();
 
   // Creates a 'default' renderer, choosing the correct implementation type.
   static Renderer* CreateDefaultRenderer(ServiceLocator* service_locator);
 
+  // Creates a 2D renderer.  This can be used instead of CreateDefaultRenderer
+  // when 3D is not supported by the underlying system, and is not strictly
+  // needed by the application.
+  static Renderer* Create2DRenderer(ServiceLocator* service_locator);
+
+
   // Gets whether or not the renderer should attempt to use the software
   // renderer.
   static bool IsForceSoftwareRenderer();
 
   // Initialises the renderer for use, claiming hardware resources.
   InitStatus Init(const DisplayWindow& display, bool off_screen);
 
   // The platform specific part of initalization.
   virtual InitStatus InitPlatformSpecific(const DisplayWindow& display,
                                           bool off_screen) = 0;
@@ skipping 611 matching lines @@
 
   // Maximum frames per second.
   int max_fps_;
 
   DISALLOW_COPY_AND_ASSIGN(Renderer);
 };
 
 }  // namespace o3d
 
 #endif  // O3D_CORE_CROSS_RENDERER_H_