I'm building a game with Ogre3d, I've got fog working properly with: scenemanager->setFog(Ogre::FOG_LINEAR, Ogre::ColourValue( 0.23f, 0.725f, 1.0f ), 0, 18, 20 );

However I'm currently implementing a GUI system (libRocket) which is rendered on top of everything else, and this removes the fog, does anyone know how to fix this? (I'm using the default libRocket rendering system for ogre as included in the samples, but this problem also appears when using a semi-transparent overlay).