Before starting to render (draw) a 3D frame, the window surface is filled out by the specified color or by a scene background texture. As a scene background texture any picture can be used. For the scene background texture similar rules are valid as for other textures: The dimensions should be power of 2 (otherwise they will be adjusted), the texture will be smoothed according to the preset smoothing of textures. Unlike with usual textures, fog, filling surfaces, texture stage or lighting cannot be applied for the scene background texture. A texture cannot be modulated by the scene background color. By setting a scene background color the scene background texture will get switched off. A scene background texture will be filtered (smoothed), if the scene switch of the object texture magnification filter is switched on.