[CREATE] OpenRaster specification: updates to support masking

[Sven Claussner]

Thank you, Andrew.
I took myself to liberty to point the GEGL devs here.
Perhaps it's also sth. for the LGM.

Kind regards,

Sven

On  17.1.2014 at 11:08 PM Andrew Chadwick wrote:
> There is now some working code to test this concept out!
>
>    → https://gitorious.org/mypaint/achadwick-mypaint/commits/layer-enhancements-exp
>
> This partially implements the proposal at
>
>    → https://gist.github.com/achadwick/7827931
>
> To mask with this branch, open the layers panel, then drag a layer
> "into" another layer to start building structure,
>
>     Group
>     ├ Layer 1
>     └ Layer 2
>
> then draw a mask in pure white in the top layer and something you want
> to mask in the lower layer in any colour you like. Set the top layer's
> compositing mode to "Destination In" using the right button menu, and
> the bottom layer (and anything else in the group) will be masked by
> the top layer. You may need to refresh the view by dragging it around
> a bit at the moment, but this annoyance should be gone soon.
>
> (It has to be in a group because MyPaint does non-isolated rendering
> onto its internal background layer. Currently you see black if a layer
> erases the background layer... The layer group implementation you see
> here uses isolated rendering only, however, and the results of that
> are then composited onto the background normally. This is just a
> workaround for now, allowing some masking experiments.)
>
> On 13 December 2013 12:01, Boudewijn Rempt <boud at valdyas.org> wrote:
>> I firmly intend to look into this into detail -- I'm not forgetting about it :-)
>>
>> On Friday 06 December 2013 Dec 16:49:10 Andrew Chadwick wrote:
>>> I'm in the process of (slowly and experimentally) refactoring the layers
>>> code in MyPaint to add a bunch of fancy features like masking, nested
>>> layers, and layer formats other than raster (but which either rasterize
>>> (like SVG) or can be represented usefully as an icon (like basically
>>> nothing right now)).
>>>
>>> I've noticed that the OpenRaster specification will need to be updated
>>> to support the Porter-Duff "in" operator, and I'd like to take the
>>> opportunity to allow sub-stacks to be composited with user-specifiable
>>> blending and compositing operators. Conveniently enough, the W3C
>>> Compositing and Blending Level 1 specification has evolved into a very
>>> helpful and complete form, and defines neatly an important aspect of how
>>> "groups" in formats like SVG - equivalent to our nested stacks - should
>>> be expected to render.
>>>
>>> Therefore I'd like to update the OpenRaster draft specification[1] in
>>> accordance with the attached proposal. See
>>> https://gist.github.com/achadwick/7827931 in case the attachment hasn't
>>> made it through the mailing list software.
>>>
>>>
>>> [1] http://www.freedesktop.org/wiki/Specifications/OpenRaster/Draft
>>>
>>>
>>
>> --
>> Boudewijn Rempt
>> http://www.valdyas.org, http://www.krita.org, http://www.boudewijnrempt.nl
>>
>> _______________________________________________
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>> CREATE at lists.freedesktop.org
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>
>
>