From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Fri, 11 Dec 2009 20:51:21 -0500
To: 9fans@9fans.net
Message-ID: <83dc09c5d930f4fa767615c7eb39f2bc@ladd.quanstro.net>
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Subject: [9fans] radar for plan 9, and two draw funnies.
Topicbox-Message-UUID: ae81de7c-ead5-11e9-9d60-3106f5b1d025

once upon a time, it was pretty easy to get a radar
image on the web.  these days, they're fancy.
the one i use is http://radar.weather.gov/ridge
which consists of a number of transparent images
that need to be overlaid.  this can be done with
page, but it's pretty painful without double-buffering,
it's tied too tightly to the screen, and panning a composed
image doesn't work.

so i wrote a program imgtype that works like doctype(1)
for images.  it's essentially stolen from page(1).  page
could use the same code.  then i wrote
a program compose that takes a series of images
of arbitrary type and composes them with SoverD.

l = (topo.jpg county.gif cities.gif warn.gif hw.gif radar.gif)
f=/lib/radar
compose $f/$l|page

this works, and is all available in contrib quanstro/radar.
it assumes you live in georgia.  so you may want to edit
the script to put the right radar source in.  bonus points
for ta script converting from /lib/sky/here to radar.  :-)

but there are two problems.

1.  for some reason the hw.gif (interstates) are
in cyan not red.  drawing the radar first and the
hw second yields inverse radar colors.

2.  the county boundaries get red and speckly
if any images are drawn on top of them, but only
if the target channel format is m8.  r8g8b8a8
works fine.  why would m8 != r8g8b8?

there's an image here
	/n/sources/contrib/quanstro/drawfunny/bad.png
	http://www.quanstro.net/plan9/bad.png

i belive this
	http://radar.weather.gov/ridge/radar.php?rid=ffc
is what it is supposed to look like.

you can also run an experiment on this directly from sources
	; cd /n/sources/contrib/quanstro/drawfunny
	; ./testinplace

i've left p9p and plan 9 source there.  the source in drawfunny
lags behind the contrib package.

- erik