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Re: CSS Light Sources

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 1 Nov 2011 10:38:33 -0700
Message-ID: <CAAWBYDD0Zmdw1d7fFu+pM8hNExKaw-xmGvkTF9kzLhuYd2NAGQ@mail.gmail.com>
To: Brian Blakely <anewpage.media@gmail.com>
Cc: www-style@w3.org
On Mon, Oct 31, 2011 at 9:28 PM, Brian Blakely <anewpage.media@gmail.com> wrote:
> Probing for input and support for a possible native lighting specification.
> This draft describes elliptical light sources that are not themselves
> visible, but manifest in the form of interactions with other parts of the
> CSS spec.
> Light sources might be a desirable addition to the CSS Filters spec in
> addition to/instead of a discreet property.

They're actually *already* part of the Filters spec - SVG has several
lighting primitives that do exactly what you ask for:
<http://www.w3.org/TR/SVG/filters.html#LightSourceDefinitions>.

There's currently no way to access these via the predefined filters -
you instead have to write a proper SVG filter and then reference it by
url() - but if that's shown to be really valuable we could change that
to have a generic shadow() filter, perhaps using an argument structure
similar to the ideas you lay out here in your email.

You could implement the current box-shadow and text-shadow via Filters
as well, but we decided that (a) they were useful enough to justify an
even shorter expression than Filters can bring, and (b) we wanted to
expose them faster than we expected Filters to expose them.  I'm not
certain that a more generic lighting model can justify itself in the
same way - the complexity difference between using Filters and using a
CSS property is smaller, and Filters are moving forward nicely, so the
time difference is basically nil.

So, I suspect we can just let Filters take care of this, possibly with
an additional shorthand function to make it easier than writing a full
SVG filter.

~TJ
Received on Tuesday, 1 November 2011 20:25:22 GMT

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