W3C home > Mailing lists > Public > www-svg@w3.org > November 2011

Re: feMergeNode opacity?

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 10 Nov 2011 12:48:50 -0800
Message-ID: <CAAWBYDBo_xq_U1L26BKRRXp0rOc0yDCNcgCjxWYrXY+3AOOHCA@mail.gmail.com>
To: David Dailey <ddailey@zoominternet.net>
Cc: www-svg@w3.org
On Thu, Nov 10, 2011 at 12:26 PM, David Dailey <ddailey@zoominternet.net> wrote:
> feFlood comes with a handy little thing:  flood-opacity.
> As I was playing a bit with feOffset at
> http://cs.sru.edu/~ddailey/svg/feOffset2.svg  I went looking for a way to
> make an feOffset partly transparent (like offset-opacity) – of course there
> is always feColorMatrix, but it isn’t the most intuitive of things for some
> authors I suspect. So that sets the stage for the question, if we have
> flood-opacity (which seems pretty focused in purpose) why not a way to make
> stages of a filter chain transparent like say an attribute that could be
> attached to any  primitive (or at least to feImage, feFlood, feOffset, or
> any mergeNode)?
> It might be a bit frilly, since we do have feColorMatrix, I suppose – and we
> could always lump n merge nodes into n-1 feComposite pairs and use
> mode=arithmetic (ick!).

You don't have to go to quite that much trouble.  You can use
feComponentTransfer to do an opacity change:

  <feFuncA type='linear' slope='[desired opacity]' />

Having an <feOpacity> element in SVG2 would make this case easier, of course.

Received on Thursday, 10 November 2011 20:49:44 UTC

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