abt gluPersepctive()

Hi, I would like to ask for the 4 parameter in gluPerspective(),
say gluPersepctive(a, b, c, d),

if i set c = 4, d = 4000, is that the thing between the distance from the camera = 4 and the distance from the camera = 4000 will be projected on the projection plane and being displayed?

Yes.