define	DUMMY	6

# CR_SURFACE -- Draw a perspective view of a surface.  The altitude
# and azimuth of the viewing angle are variable.

procedure cr_surface(gp, data, ncols, nlines, angh, angv)

pointer	gp			# GIO pointer
real	data[ncols,nlines]	# Surface data to be plotted
int	ncols, nlines		# Dimensions of surface
real	angh, angv		# Orientation of surface (degrees)

int	wkid
pointer	sp, work

int	first
real	vpx1, vpx2, vpy1, vpy2
common  /frstfg/ first
common  /noaovp/ vpx1, vpx2, vpy1, vpy2

begin
	call smark (sp)
	call salloc (work, 2 * ncols * nlines + ncols + nlines, TY_REAL)

	# Initialize surface common blocks
	first = 1
	call srfabd()

	# Define viewport.
	call ggview (gp, vpx1, vpx2, vpy1, vpy2) 

	# Link GKS to GIO
	wkid = 1
	call gopks (STDERR)
	call gopwk (wkid, DUMMY, gp)
	call gacwk (wkid)

	call ezsrfc (data, ncols, nlines, angh, angv, Memr[work])

	call gdawk (wkid)
	# We don't want to close the GIO pointer.
	#call gclwk (wkid)
	call gclks ()

	call sfree (sp)
end