Procedural Texture layer ignored in Group

[generalpurpose]

Issue

Affinity Photo 2.0.4

It appears that Procedural Texture layers are ignored when moved inside of a group.

I'm still pretty new to Affinity Photo/Procedural Textures and might not fully understand how this layer should be used and if this behavior is possibly by design. Specifically, I'm not sure if this layer is expected to only be used as a "modifier" of other layers or if it can live on its own as a texture "generator".

 

Reproduction Steps

1. Create a new blank document
2. Add a Procedural Texture Live Filter layer with the following settings (the values themselves are not important, as long there is data in at least A and one color channel):
   
3. The document is now completely red:
   
4. Put the Procedural Texture layer into a Group and leave the default blending mode of Passthrough
5. The document is now completely white, as if the Procedural Texture is ignored:
   

 

Expected Result

After step #4, I would expect the document to still be red since the group doesn't have any mask that would stop it from being displayed.

Edited April 11, 2023 by chairpants

[GarryP]

Welcome to the forums @chairpants

Unless I’m mistaken, the observation which you are describing is expected behaviour.

The way I think about it, the Live Filters take the pixels/content from <something>, manipulate that <something> and produce <a (possibly) different thing>.
In other words, in general, but not always, they need <something> to manipulate in order to produce <something else>.

A document has an ‘inherent’ transparent background whether you tell the software that the background is transparent or not.
A non-transparent background – the white rectangle that you can see – is not counted by the live filters as ‘a thing to be manipulated’.

You can see this if you change your Live Procedural Texture Filter settings to not affect the Alpha channel.
With the filter only affecting the Red channel you will see no change because the blank document doesn’t have any content.
Alternatively, with the filter affecting the Red and Alpha channels you will see a red rectangle because the filter is now affecting the transparent (Alpha) background and turning it red.

If you add a Live Filter to a Group which contains no other layers, because that group has no content, the live filter has nothing to manipulate and, therefore, you will see no difference – there’s nothing in the group to manipulate and so there’s nothing to see.

I don’t think this is a bug, it’s just the way the software is supposed to work (unless someone can prove otherwise).

Note: See later posts for further details.

Note: [inserted clarification]

Edited April 12, 2023 by GarryP
Added clarification.

[NotMyFault]

3 hours ago, GarryP said:

In other words, they need <something> to manipulate in order to produce <something else>

that is not correct. 

PT filter can create something from scratch, when you set the alpha channel to non-zero.same applies to e.g channels mixer where you can set an offset on alpha.

But if you nest any filter / adjustment to child position, the alpha channel gets clipped to areas where alpha is non-zero (by lower layers).

simply drag the filter to masking position, and alpha starts working even on empty groups.

The file below shows it:

• the red rectangle is from the lower group, and alpha is 1 in the upper half of the canvas, PT nested to child position
• the green rectangle is from the upper group, and alpha is 1 in the left half of the canvas, PT nested to masking position

 

 

PT filter within group.afphoto

[GarryP]

Thanks for the explanation but it’s gone way over my head, e.g. “set an offset on alpha”, “alpha channel gets clipped”, “drag the filter to masking position”, etc.

If you can provide a video at some point then that should be useful for me and others.

[NotMyFault]

1 minute ago, GarryP said:

Thanks for the explanation but it’s gone way over my head, e.g. “set an offset on alpha”, “alpha channel gets clipped”, “drag the filter to masking position”, etc.

If you can provide a video at some point then that should be useful for me and others.

just updated my older post and included a test file & screenshots

[NotMyFault]

7 minutes ago, GarryP said:

set an offset on alpha”

1. add a channels mixer
2. choose alpha channel
3. set the offset to a value >0

[GarryP]

Thanks for the extra information.
This is way beyond what I use those parts of the software for.
I’ve slightly edited my earlier post to suggest that what I said there isn’t the whole picture.