Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!AMD-26.HAC.COM!dhuff
From: dhuff@AMD-26.HAC.COM (Daryl Huff)
Newsgroups: comp.windows.x
Subject: X line definition
Message-ID: <8906161725.AA02074@amd-26.hac.com>
Date: 16 Jun 89 17:25:30 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 35

I am in the process of developing a plane for porting the X11R3 server 
to a new graphics engine and need a bit of help in two areas.  (I'm fairly
new to X Windows as well as expert so, sorry if these questions have been 
covered before.)

The first area I am having trouble in is estimating the memory requirements
of the X Windows server.  I am trying to assess the feasibility of porting
X server to a system without a disk. Therefore I need to get an idea of 
the amount of main memory that would be required in this type of a system.
I realize the answer to this question is dependent
on many things including the number of windows open, the number of fonts
loaded, where I store my pixmaps (main memory or in the frame buffers), etc.

The second question is about the line alorithm of the X server.  The 
X protocol specification defines a line to be a filled rectangle with 
vertices at:
    
     [x1-(w*sn/2),y1+(w*cs/2)],[x1+(w*sn/2),y1-(w*cs/2)],
     [x2-(w*sn/2),y2+(w*cs/2)],[x2+(w*sn/2),y2-(w*cs/2)]

using the fill algorithm also defined in the protocol spec.  The problem
I have is that in the "Strategies for Porting the X v11 Sample Server", 
dated March 1, 1988, section 2.4.14.2. (Second Round Optimizations), 
describes how to optimize the line drawing performance of X by implementing
a Bresenham edge walker.  First, I don't believe that line drawn with
Bresenham's algorithm conforms to the X definition of a line.  Second, I
am confused by the reference to a need for multiplication and
division in implementing Bresenham's algorithm since the algorithm was 
developed to avoid the need for multiplication and division when solving 
for a line.

Any help in these two areas would be appreciated.

                                 Daryl Huff
                                 Hughes Aircraft Co.