Yes I could just use the boolean difference when the hidden line feature will be ready. But still I have to select by hand all the objects to delete. The problem is that this method is geometry-destructive, I mean that I always have to make a copy of the model or the file before doing it. What I was looking for, was an automated process for plane creation (from a line), difference, delete objects, generate drawing, and then undo the boolean operation! No need for hatch patterns, I always do hatching in Archicad or illustrator. But it's ok I can do it manually, I really want to try this new hidden line feature!
thanks,
m