SUBROUTINE CUBE

 CUBE plots the 6 surface polygons of a 3-d "cube" into the  INIT3DH 3-d plotting package. Either  SKETCH or  PLT3DH may be used.

CALL CUBE (x1,x2,y1,y2,z1,z2,i,h)

x1,y1,z1 (R): corner of cube
x2,y2,z2 (R): oposite corner of "cube" from corner 1
i        (I): SKETCH flag for last SKETCH call in routine
              Note: (returned) value is the SKETCH return
h        (L): hide flag
              = .TRUE.   SKETCH routine used
              = .FALSE.  PLT3DH routine used