;+
; NAME:
;	vu_vox_drawelongitude
; PURPOSE:
;	Internal use by vu_vox_showeclipgrid only
; CATEGORY:
;	Volume Pro board
; CALLING SEQUENCE:
	FUNCTIOn vu_vox_drawelongitude, F,ut,zero_lng,earthlng,lng,cntr,dvox, obj_val
; INCLUDE:
	@compile_opt.pro			; On error, return to caller
; CALLS:
;	gridgen,replicate,cv_coord,round,CvSky
; CALLED BY:
;	vu_vox_showeclipgrid
; MODIFICATION HISTORY:
;	JUL-2002,Cindy Wang xin_wang02@hotmail.com
;-
n = 180

P = gridgen(n, range=-n/2+[0,n-1])

P = replicate(1,3)#P
P[0,*] = earthlng+lng
P[2,*] = 1

P = CvSky(ut, from_ecliptic=P, /to_heliographic, /degree, /silent)

P[0,*] -= zero_lng

P = cv_coord(from_sphere=P, /to_rect, /degrees)
P = round( cntr+P*dvox )

F[P[0,*], P[1,*], P[2,*]] = obj_val

RETURN, F  &  END