From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] printing via local attached printer with gs driver
From: "Russ Cox" <rsc@swtch.com>
Date: Mon, 18 Jun 2007 14:00:30 -0400
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Did you compile your own copy of ghostscript?
This is a common problem if you compile directly
from the gs sources; there are some Plan 9 specific
changes that must be made.  See /sys/src/cmd/gs/mkfile:

# If you get weird floating point errors, the culprit is usually the
# halftone code, which converts double to uint, something 8c handles
# incorrectly (treats as double to int).  Look in src/gshtscr.c for a line like
#
# 	sample = (ht_sample_t)((value+1) * max_ht_sample);
#
# and change it to one of:
#
# 	sample = (int)(vlong)((value+1) * max_ht_sample);
#	sample = (ht_sample_t)(value * max_ht_sample) + max_ht_sample;
#
# depending on your preference.
#
# Also, recent versions of src/gxshade1.c cause the compiler to run out
# of registers.  Brucee is looking into this.  In the meantime, use this
# replacement:
#
#	private inline void
#	make_other_poles(patch_curve_t curve[4])
#	{
#	    int i, j;
#
#	    for (i = 0; i < 4; i++) {
#		j = (i + 1) % 4;
#		curve[i].control[0].x = (curve[i].vertex.p.x * 2 + curve[j].vertex.p.x);
#		curve[i].control[0].x /= 3;
#		curve[i].control[0].y = (curve[i].vertex.p.y * 2 + curve[j].vertex.p.y);
#		curve[i].control[0].y /= 3;
#		curve[i].control[1].x = (curve[i].vertex.p.x + curve[j].vertex.p.x * 2);
#		curve[i].control[1].y /= 3;
#		curve[i].control[1].y = (curve[i].vertex.p.y + curve[j].vertex.p.y * 2);
#		curve[i].control[1].y /= 3;
#		curve[i].straight = true;
#	    }
#	}
#
# (the original includes the /3 in the big expressions).

The source in the distribution should be patched already.
Also I thought I fixed 8c to do the right float -> uint
conversion, but it would have been quite a while ago
and I don't remember.

Russ