Since 1.1 there is the "params" button on top of the "home" one. It leads to a panel that permits to specify some visualization parameters. For example you can now render a FOG file in solid with or without lightening. The "lighten cube" example had been added to play with this feature. See Gallery for some pictures.
Step by step, arrange to have "light on" and "solid" to true and then click "Ok" :
Then load a FOG file, for example the "examples/ATLAS/END.fog". By playing with the camera you can have :
Come back to the camera panel to set "light on" to false, you should have :
which is an "industrial" kind of drawing. Triangles are rendered in flat colors and edges are rendered with black lines. Note that if changing back "solid" to false, you have to recreate the scene graph to take it into account.
This is so because "solid" is a modeling parameter that needs a new scene graph, whilst "light on" changes the field of an existing node in the scene graph and then is taken into account immediatly at the next redraw.