underlay(3G) underlay(3G)
NAME
underlay - sets the number of user-defined bitplanes used
for underlay color
SPECIFICATION
C underlay(planes)
long planes;
FORTRAN subroutine underl(planes)
integer*4 planes
DESCRIPTION
underlay sets the number of user-defined bitplanes used for
underlay colors. planes is the number of bitplanes that you
want to use for the underlay, 0 or 2. The underlay color
appears whenever all the bits in the color bitplanes are
zero. The system has two bitplanes that can be allocated to
underlay or overlay. underlay sets them as underlay allowing
four underlay colors. underlay and overlay cannot both be
set to 2 at the same time.
Setting underlay to 2 forces overlay to zero, and vice
versa. The default value of underlay is zero.
Call gconfig after underlay to activate the underlay
setting.
When the drawing mode is UNDERDRAW, all drawing occurs in
the underlay bitplanes. In UNDERDRAW, FLAT is the only
shading model available.
SEE ALSO
color, cmode, drawmode, writemask, shademodel, overlay
Programming Guide, Section 6.4, Overlay and Underlay Modes
NOTE
This routine is available only in immediate mode.
Page 1 (printed 8/20/87)