The set hidden3d command enables hidden line removal for explicit surface plotting (see splot). Hidden line removal may be used for both explicit functions and for explicit data. It now works for parametric surfaces as well.
When this flag is set both the surface hidden portion and possibly its hidden contours (see set contour) as well as the hidden grid will be removed. Labels and arrows are always visible and are unaffected by this command.
Each surface has its hidden parts removed with respect to itself and to other surfaces, if more than one surface is plotted. This mode is meaningful when surfaces are plotted using line style drawing only.
Syntax:
set hidden3d
set nohidden3d
show hidden3d