Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!ncar!ico!auto-trol!marbru
From: marbru@auto-trol.UUCP (Martin Brunecky)
Newsgroups: comp.windows.x
Subject: Re: Rubberbanding woes too!
Keywords: xor drawing decwindows
Message-ID: <874@auto-trol.UUCP>
Date: 10 Oct 90 16:11:17 GMT
References: <277@sps.com> <862@auto-trol.UUCP> <10309@nfs4.rl.ac.uk>
Reply-To: marbru@auto-trol.UUCP (Martin Brunecky)
Organization: Auto-trol Technology, Denver
Lines: 41

In article <10309@nfs4.rl.ac.uk> caag@inf.rl.ac.uk (Crispin Goswell) writes:
>In article <862@auto-trol.UUCP> marbru@auto-trol.UUCP (Martin Brunecky) writes:
>>In article <277@sps.com> wwb@sps.com (Bud Bach) writes:
>>>
>You may be jumping to conclusions here. The last DECwindows server I used
>(Ultrix 3.? DECstation 3100, 8-plane color) had a bug with Xor mode.
>It seemed to perform a GXequiv instead of GXxor. GXequiv works as expected.
>I've not reported this because we do not have Ultrix 4.0 yet.
>
   Xor on DECstation 3100, 8-plane color, ULTRIX 4.0 works right.
  (I can't guarantee it for other modes -)

>We use some unusual techniques which are related to this, and may be of
>interest.  We have many applications which do clever things
>with monochrome rasterops using a locally written graphics library.
>(masking, Xoring, highlighting by GXinvert, etc).
.....
>Usually only one of these will contain set bits, but when they both do,
>two graphics requests will be necessary, one with the given alu function
>and a planemask containing the bits in the first case, and one with the
>inverse of the alu function (e.g. for GXcopy use GXcopyInverted) and a
>planemask containing the bits from the second case.
>
   Interesting concept. Thanx. However, for my rubberbandings I can't
   afford to do things twice. With size and/or complexity of my animations
   the intermediate artifacts become too visible to annoy the user.
   
   As a simple example, (in the past) we tried to drag around a Color pixmap.
   Save area, blit my picture on it, restore, blit in a new position. It did
   work, but even when we minimized number of saves by pre-saving larger areas,
   it just did not fly. Xor looks much better, especially when you can
   pack undraw/draw new position into a single protocol request (draw segments),
   but even two copy area/planes followed by flush do well.



-- 
=*= Opinions presented here are solely of my own and not those of Auto-trol =*=
Martin Brunecky                   marbru@auto-trol.COM
(303) 252-2499                    {...}ncar!ico!auto-trol!marbru
Auto-trol Technology Corp. 12500 North Washington St., Denver, CO 80241-2404