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List: rrd-users
Subject: Re: [rrd-users] Trend to show cloud height -Weather Station
From: Simon Hobson <linux () thehobsons ! co ! uk>
Date: 2011-02-19 9:40:40
Message-ID: p0624080ac9853f873069 () simon ! thehobsons ! co ! uk
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Robert Conway wrote:
>Is there a hex colour value for totally transparent ?
You can optionally specify a fourth byte for the colour value - and
if you do it is used as a transparency value. It's useful where you
want to plot an area (such as min-max band) without obliterating
what's below it.
So for example, for a pale blue, you can either use "pale blue"
(BFBFFF), or you can use "blue" (0000FF) with transparency 0000FF3F
which will give a pale blue over a white background but allow the
underlying features to show through.
The only way I could see of getting clouds would be to use an image
as the plot area initial fill (which isn't supported, though I'd
imagine it might not be hard to hack), then plot a solid white area
up to the cloudbase to obliterate it.
--
Simon Hobson
Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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