Images at:
http://www.ecs.soton.ac.uk/~jmb202/riscos/netsurf/zoom-fixedpoint.gif
http://www.ecs.soton.ac.uk/~jmb202/riscos/netsurf/zoom-integer-floatingpoint.gif
J.
---------- Forwarded message ----------
Date: Wed, 24 Oct 2007 02:23:01 +0200
From: Franz Korntner <[EMAIL PROTECTED]>
To: John-Mark Bell <[EMAIL PROTECTED]>
Subject: Fixed-point arithmetic
Hi John,
I'm posting this one private because it has large attachments and i'm not quite
sure if submitting them will nuke the mailing list.
I've eliminated all floating-point operations from the rendering core and
replaced them with fixed point (i.e. effectively integer operations). It
revealed much in expected and unexpected areas but more of that later. For an
illustration I included 2 animated gifs of a rendered test page consisting of a
10x10 table containing 2 by 2 pixel red images wrapped in alternating
blue/black 2 pixel padding. Goal of this test is to illustrate rounding errors.
The gif animation zooms into the page 100 times.
The first attachment is with the original mixed integer/float code, the second
with fixed point arithmetic.
Franz.
