import grid3; size(10cm,0,IgnoreAspect); currentprojection=orthographic(0.25,1,0.25); limits((-2,-2,0),(0,2,2)); xaxis3(Label("$x$",position=EndPoint,align=Z), YZEquals(-2,0), OutTicks(Label(align=0.5*(Z-Y)),Step=0.5, gridroutine=XYgrid)); yaxis3(Label("$y$",position=EndPoint,align=-X), XZEquals(-2,0), InOutTicks(Label(align=0.5*(Z-X)),N=8,n=2, gridroutine=YX_YZgrid)); zaxis3("$z$", OutTicks(ZYgrid));