Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!pyramid!prls!philabs!linus!mbunix!rachamp
From: rachamp@mbunix.mitre.org (Richard A. Champeaux)
Newsgroups: comp.sys.amiga
Subject: Re: PLT:, HPGL, DumpRastPort()
Summary: some things I forgot to mention in my last post
Keywords: PLT:, HPGL, DumpRastPort, CAD, handler
Message-ID: <55948@linus.UUCP>
Date: 12 Jun 89 15:14:09 GMT
References: <5375@rpi.edu> <2125@hp-sdd.hp.com> <55947@linus.UUCP>
Sender: news@linus.UUCP
Reply-To: rachamp@mbunix (Champeaux)
Distribution: usa
Organization: The MITRE Corporation, Bedford, Mass.
Lines: 23


   I forgot to address some things in my response to Tony's post.

On color support:

   What I'm currently doing when there are interseting lines of different
colors is putting the darker color down.  After the pen colors are read,
I determine each one's brightness.  Currently this is done merely by adding
the R, G, and B fields together.  The SetPixel() function compares the 
brightness of the color of the point in the raster to the color it's trying
set.  The color that is put there is the darker of the two colors.  Although
this will not accruately emulate the mixing of the colors on a page, it's
as close as I can think of doing it.  On a real plotter, a yellow and blue
line might mix to give you green (depending on the type of pen and paper).
On my implementation, the yellow dots would become blue dots where the lines
intersected.

On printer driver resets and formfeeds:
   I found two flags in the 1.3 RKM that solved this problem.  They were
SPECIAL_NOFORMFEED and SPECIAL_TRUSTME.  The only thing I have do to do now
is look to see how to send a formfeed at the of the plot.

Rich Champeaux (rachamp@MBUNIX.MITRE.ORG)