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From: callahan@cs.jhu.edu (Paul Callahan)
Newsgroups: comp.theory.cell-automata,comp.windows.x
Subject: Re: Xlife 3.0
Message-ID: <callahan.669931123@newton.cs.jhu.edu>
Date: 25 Mar 91 19:56:41 GMT
References: <wbvK9dO00awJ8ClYJc@andrew.cmu.edu>
Reply-To: callahan@newton.cs.jhu.edu.UUCP (Paul Callahan)
Organization: JHU Computer Science Deparment, Baltimore MD
Lines: 47

In article <wbvK9dO00awJ8ClYJc@andrew.cmu.edu> jb7m+@andrew.cmu.edu (Jon C. R. Bennett) writes:
> [ about the new release of Xlife ]

I wrote most of the user interface and file loading extensions very recently,
and there may still be some bugs or inconsistencies with the last release.
I tried to cater the new stuff to careful life tinkering as opposed to just
loading and watching.  I'm very interested in making the interface as usable
as possible, so I'd like comments and bug reports.  Assuming I have time, I'll 
try to track down these bugs (or convince you that they're features :-).  

I just found a bug when trying load files in absolute format.  It comes up
if you've moved the view before loading.  Basically, it's an inconsistency 
between new code and old.  I suspect most of the bugs will be of this nature.
The fix is as follows:

Go to the statement at line 497 in file.c:

     addcell(xpos + ...,
              ypos + ... )

This should be changed to

     addcell((xpos-loadx)+STARTPOS + ...,
              (ypos-loady)+STARTPOS + ... )

This will cause absolute mode patterns to be loaded in the upper left corner
of the displayed area.  Without this fix, the pattern appears at some bizarre
location that is not displayed.  

To get around the problem without fixing the source, you have two choices. 

(a) don't use absolute mode (i.e. recite the mantra "absolute == obsolete" 
until you feel enlightenment coming upon you).  This will also mean appending 
"#R" to the beginning of all non-picture files produced by 'S'.

(b) First do 'I' on loaded file, and use the center-of-mass command ('5') to
put the pattern in view.

I thought I did reasonable testing on Xlife, but it was mainly with respect
to the features I use.  I don't use absolute mode, and I don't use 'S' on
patterns too big to save as pictures (which is why I added the include 
extensions).  I don't want to make Xlife harder to use for people who do
use these things, so please report any anomalies and I'll try to fix them.

--
Paul Callahan
callahan@cs.jhu.edu