what is sketchup non-photo-realistic algorithm?

recently I installed sketchup and found that its method to display the model is a non-photo-realistic one. To be compared with freestyle, sketchup can generate all the NPR features very quickly, and change the styles easily.
So, which algorithm does sketchup use, and can this be borrowed by Blender?

Possible this is as realtime it is part of what OpenGL can do. Games like borderlands use this as well. Blenders game engine can do it as well to a certain degree I think.

“quake 3 arena”

if OpenGL do the magic. how can we do this in Blender?