From: Hans Hagen <pragma@wxs.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: drawarrow and transparency
Date: Sat, 05 May 2012 11:19:07 +0200 [thread overview]
Message-ID: <4FA4F08B.3000604@wxs.nl> (raw)
In-Reply-To: <20120502173518.604e1545@sole.extra.cea.fr>
On 2-5-2012 17:35, Alan BRASLAU wrote:
> I have a MetaPost question concerning drawarrow withtransparency
> (or any other compound object).
>
> Is there some clever way to achieve uniform transparency
> for a compound object? For example, in the minimal example
> below, how can one obtain a transparent arrow without getting
> an X-ray vision of the arrowhead?
>
> \starttext
> \startMPpage
> drawarrow origin--(1cm,0) withtransparency(1,.5) ;
> drawarrow origin--(0,1cm) withtransparency(1,.5) ;
> \stopMPpage
> \stoptext
This is a side effect of an arrow being a composed graphic. I
experimented a bit with transparency grouping and after several variants
I settled to the following approach:
\starttext
\startMPpage[offset=1mm]
drawarrow (1cm,0cm) -- (0cm,0cm) withcolor red
withtransparency(1,.5) ;
draw image (
drawarrow (1cm,0cm) -- (0cm,0cm) withcolor red
withtransparency(1,.5) ;
) shifted (0,2mm) asgroup "" ;
draw image (
drawarrow (1cm,0cm) -- (0cm,0cm) withcolor red
withtransparency(1,.5) ;
) shifted (0,4mm) asgroup "isolated" ;
draw image (
drawarrow (1cm,0cm) -- (0cm,0cm) withcolor red
withtransparency(1,.5) ;
) shifted (0,6mm) asgroup "knockout" ;
draw image (
drawarrow (1cm,0cm) -- (0cm,0cm) withcolor red
withtransparency(1,.5) ;
) shifted (0,8mm) asgroup "isolated,knockout" ;
addbackground withcolor green ;
\stopMPpage
\stoptext
As we have to use xforms (a pitty that this is needed) there is the
usual interference and something fishy with clipping is going on.
Hans
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prev parent reply other threads:[~2012-05-05 9:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-02 15:35 Alan BRASLAU
2012-05-02 19:42 ` Marco
2012-05-03 10:32 ` Alan BRASLAU
2012-05-03 12:47 ` Rogers, Michael K
2012-05-03 14:09 ` Peter Rolf
2012-05-05 9:19 ` Hans Hagen [this message]
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