javascript - Remove floor inside the model -

i using threejs render house model. try make grass around house. problem if grass ordinary plane appears inside house (see first screenshot) , doesn't let go vault. i've tried remove part of floor using bounding box of house, causes problems in other models (holes in floor, see screenshot). need way retain grass outside , remove inside house, don't know how it.

any appreciated!

you replace current single grass plane 4 bounded planes not enter house.

+-----------+ |     1     | +---+---+---+ | 2 |   | 3 | +---+---+---+ |     4     | +-----------+ 

edit option use constructive solid geometry (csg):

• http://learningthreejs.com/blog/2011/12/10/constructive-solid-geometry-with-csg-js/