void d3bars (barson) D#PLT.C Level 3
float barson The size of the bars as a fraction of the bar spacing. Any nonzero value turns on the 3-D bars mode.
Calling d3bars() with a positive real argument sets the 3-D bars mode. Bars are drawn instead of the default wire-mesh pattern wheneither  surmat(), surmatc(), or surfun() is called in this mode. A later call with argument 0.0f restores normal 3-D operation.