[comp.sys.sgi] # of overlay planes

weinhous@CASTOR.WUSTL.EDU ("Martin S. Weinhous") (08/17/89)

Thant,
  In your note to info-iris you asked ...
 
TT> Four bits are for overlay and four are for window I.D.  That's how the 
TT> machine does arbitrarily shaped and/or overlaping windows in different
TT> modes that can be independently swapped, all without any performance hit.
TT> 
TT> If you talk about what you need the 8 overlays for, somebody may have a
TT> a better/workable solution.  (What machine had 24 bits of color AND 8 bits
TT> of overlay?)
 
  Many image processing systems, particularly those intended for the
processing of gray-scale images provide the capability of using 8 bit
planes of overlay.  This allows the user to, easily,  non destructively,
annotate the gray-scale images with up to 256 colors.  I'd like to do
the same on my 4D120-GTX, but can't.

  And, while I have you on the "line."  Note the TT>  prefix to lines
from your message.  I had to ~m (interpolate) your message then use vi
to change the first character from <tab> to TT> for each line.  Why
dosen't set indentprefix work for Mail?  Any suggestions?
--

						Marty Weinhous
					  <weinhous@castor.wustl.edu>
				 	<...!uunet!wucs1!dinorah!weinhous>

thant@horus.sgi.com (08/17/89)

Howdy,

Yeah, people have been telling me about a lot of machines that have eight 
overlays.

If you are only doing greyscale stuff, you could use colormap mode with
writemask.  The colormap is twelve bits big, so the bottom eight would
contain the picture and the top four could be overlay.  This is separate
from the overlay planes proper so you only get twice the colors, not n 
squared.

Another thing you might think about is keeping a copy of the image in the
z-buffer, and go ahead and draw right on top of the image in the display
planes, and any time you wanted to "erase" or "move" the overlay, just
copy portions or the whole picture back from the z-buffer using rectcopy.

This would allow your overlays to be double-buffered.

thant@sgi.com

thant@horus.sgi.com (08/17/89)

P.P.S.  I'm no good at mail stuff.  (That stuff's all black magic to me.)

thant

vjs@rhyolite.wpd.sgi.com (Vernon Schryver) (08/17/89)

In article <8908161833.AA12079@castor.wustl.edu>, weinhous@CASTOR.WUSTL.EDU ("Martin S. Weinhous") writes:
> ...
>   And, while I have you on the "line."  Note the TT>  prefix to lines
> from your message.  I had to ~m (interpolate) your message then use vi
> to change the first character from <tab> to TT> for each line.  Why
> dosen't set indentprefix work for Mail?  Any suggestions?
> 						Marty Weinhous
> 					  <weinhous@castor.wustl.edu>
> 				 	<...!uunet!wucs1!dinorah!weinhous>

`grep -i prefix *` on the 4.3-Tahoe, 4.3BSD, and SVR3.2 mailx source
finds nothing obviously related.  Transmit() in collect.c in 4.3Tahoe
and SVR3.2 mailx simply putc('\t'), without checking anything for
permission.

The easiest work around is probably to build a vi macro.  One generally
needs to edit a reply to remove the zillion mail headers


Vernon Schryver
Silicon Graphics
vjs@sgi.com

jdchrist@watcgl.waterloo.edu (Dan Christensen) (08/17/89)

In article <8908161833.AA12079@castor.wustl.edu> weinhous@CASTOR.WUSTL.EDU ("Martin S. Weinhous") writes:
>  Many image processing systems, particularly those intended for the
>processing of gray-scale images provide the capability of using 8 bit
>planes of overlay.  This allows the user to, easily,  non destructively,
>annotate the gray-scale images with up to 256 colors.  I'd like to do
>the same on my 4D120-GTX, but can't.

You should be able to use colour map mode and writemasks to achieve
what you want to do.  How many bits do you need for the gray scale?

----
Dan Christensen, Computer Graphics Lab,	         jdchrist@watcgl.uwaterloo.ca
University of Waterloo, Waterloo, Ont.	         jdchrist@watcgl.waterloo.edu