15.40.2  DEPTH 

DEPTH=OFF  plots  the  mesh as a series of disconnected histograms, rather
than as a solid.  Each histogram is drawn as a flat  2  dimensional  hist,
but  one after the other.  Necessary lines to delineate edges of different
planes are included when a plot with depth is requested.  By omitting some
lines the plot is much faster.
(Default:DEPTH=ON)

If  you  wish  to  pick which axes is histogrammed you may use the options
X,Y,Z