c
c    Action routine for PLOT3D command
c
c    last modified on 20.2.99 by R.Holzmann
c
      subroutine hplot3d
      real*4  x(3,2), u(2), v(2)
      character*32 chpatl
      integer*4 icol
      save icol

      call kupatl(chpatl,narg)  ! get number of arguments...
      call kugetr(x(1,1))       ! ... and read them one be one
      call kugetr(x(2,1))
      call kugetr(x(3,1))
      call kugetr(x(1,2))
      call kugetr(x(2,2))
      call kugetr(x(3,2))
      if(narg.gt.6) then        ! icol is optional, if not given reuse previous
         call kugeti(icol)      ! saved one
      endif

      call gdfr3d(x,-2,u,v)    ! transform from 3D master reference to 2D proj
      if(icol.ge.0) call gdcol(icol)  ! change to new colour
      call gdrawv(u,v,2)              ! plot polyline
      if(icol.gt.0) call gdcol(0)     ! go back to previous GEANT colour

      return
      end