Alpha Dependencies!
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    caneron
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    Alpha Dependencies!

    by caneron » Mon Sep 30, 2019 4:48 pm

    If I create a layer that I want to function as an alpha over all layers, it's easy with the old blend mode selection.

    If I want an alpha to only effect certain layers, it would make sense to drop that as the top layer in a group. However, that alpha effects all layers below (regardless of within a group or not). Would be great for that alpha to only effect that group!

    Further, Stencil and Silhouette Luma work great, But where's Stencil Alpha? Obviously I can invert, but that's one extra step :D
  • franz
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    Re: Alpha Dependencies!

    by franz » Thu Oct 03, 2019 4:15 pm

    we're doing live graphics with opengl, not offline image like photoshop.
    Due to how works opengl, each layer will affect everything that's underneath.

    Doing what you want would require pre-compositing, like rendering to an "invisible" target then use that for compositing.
    Definetly not feasible in our live scenario.

    Having said that, you could pre-compose yourself by rendering to a virtal projector with syphon/spout output enabled, that way you can get your comp back as a single texture.

    Hope this helps
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    caneron
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    Re: Alpha Dependencies!

    by caneron » Thu Oct 17, 2019 6:56 pm

    Franz good call. How bad is that workaround on the old overhead?

    Would be great to have some sort of "pre-comp" tool that does this workaround for you.
  • franz
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    Re: Alpha Dependencies!

    by franz » Mon Oct 21, 2019 4:47 pm

    you can already pre-comp in 2 clicks.

    - 1: create a projector (but don't assign it any physical display output)
    optional: rename it to something meaningful, such as "Pre-comp"
    - 2: enable Syphon/Spout output.

    Now everything that happens within that projector's boundary will be accessible for other surfaces as a texture,
    namely under the "Syphon/spout" media category, (should be named "madmapper pre-comp")

    Assign that texture to any of your surface.

    Note that with this technique you can achieve feedback looping as well.
    It is not bad for performances unless you're pre-comping 4k on a laptop... I actually use this technique all the time for LED content.
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    caneron
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    Re: Alpha Dependencies!

    by caneron » Wed Oct 23, 2019 2:13 pm

    Incredibly useful, Franz. Thanks

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