Multiple masks lead to alpha failure

[NotMyFault]

Hi,

i just made a tutorial showing how to use multiple masks in additive way. Works great for regular masks.

https://forum.affinity.serif.com/index.php?/topic/142430-non-destrcutive-workflow-using-masks-additive-revealing-from-both-masks-instead-of-hiding/

When i tried to extend this approach by adding a vector shape (used as mask), once again the handling of alpha channel gets confused in Photo. Symptoms will depend on OpenCL active / inactive.

To reproduce, open the file, select the vector shape "Double Star", and transform size and/or position.

OpenCL inactive:

• The shape will be embedded into a rectangular area of dynamic size, where the alpha channel is not calculated properly (becoming 0 instead of 1)

OpenCL active:

• When transforming the vector shape, it leaves an trail of alpha set to zero, partially recovering, partially staying zero.

 

Win 10, 1.9.2.1035 and beta 1.9.4.1065

 

Don't get distracted by the multiple adjustments (curves, channel mixer, levels) - i tried all as they are able to influence the alpha channel. You can activate any one of them, identical results.

additive mask with vector issue.afphoto

[AiDon]

Why don't you post in the Beta forum? This is the production forum.

[NotMyFault]

6 hours ago, AiDon said:

Why don't you post in the Beta forum? This is the production forum.

Because it affects both stable and beta. This is only to prevent the next question "did you test the latest beta". I already did that extra test. As i did test both OpenCL on and off. To save time for all involved.

The beta forum clearly says to post only beta-related issues.

 

[Chris B]

Thanks. I can reproduce the issue described and I am seeing the differences with OpenCL on/off.

However I see weird results on macOS too - zooming changes how the document redraws for both Windows and macOS.

[NotMyFault]

I've reduced the issue to the essence:

• 1 vector shape or curves layer
• 1 alpha-sensitive adjustment  layer (channel mixer, levels, curves) inverting the alpha channel

Now you get the same rectangular halos around the vector shape when zooming or transforming.

The color is an intentional side effect  just for fun to make live less grey. Just reset the RGB channels of the channel mixer to get rid of it.

 

curves inverse alpha issue.afphoto