Vertex alpha not applied

[artechdowon]

I am currently using Blender 4.3.
There is no problem painting general vertex colors.
However, if I isolate the A channel for the alpha channel and apply changes after painting, the painted alpha value is not saved.
When I check the attribute value, I confirmed that the value changes when painting the alpha channel, but after applying, all values ​​are reset to 1.000.

When I create a new blender file and paint the alpha channel, it is saved in the attribute, but in some scenes, all alpha channel values ​​are lost.

My guess is that when you paint vertex alphas larger than a certain size, all information gets reset.

[Andrej730]

@artechdowon attached demo appears to be broken.

Couldn't reproduce this:

However, if I isolate the A channel for the alpha channel and apply changes after painting, the painted alpha value is not saved.
When I check the attribute value, I confirmed that the value changes when painting the alpha channel, but after applying, all values ​​are reset to 1.000.

[artechdowon]

@artechdowon attached demo appears to be broken.

Couldn't reproduce this:

However, if I isolate the A channel for the alpha channel and apply changes after painting, the painted alpha value is not saved.
When I check the attribute value, I confirmed that the value changes when painting the alpha channel, but after applying, all values ​​are reset to 1.000.

sry, I re-uploaded the gif file..
I wonder if it has something to do with the Blender version? I am using version 4.3.
After applying vertex alpha and saving, when I run Blender again, all the information values ​​are gone.

[Andrej730]

After applying vertex alpha and saving, when I run Blender again, all the information values ​​are gone.

Alpha is not gone, it's just not very visibile - check spreadsheet for the real values in attributes.

By default vertex paint only works with RGB and to work with Alpha, VCM is starting a special mode where you paint alpha using RGB and then it's saved as just Alpha.

blender_Lrt5bTP1rk.mp4

[artechdowon]

I tested the issues in detail.

• When Blender is running, alpha colors are displayed in the viewport when converting the A channel to isolate.
  When Blender is closed and the file is opened again, the alpha color is no longer visible. (It is recorded in the spreadsheet.)

• When working on the alpha channel for other objects, the alpha is not visible. <- I wonder if it is the case when there is a certain number of vertices or more.

• When I check the spreadsheet after applying, the information is saved.

When I isolate the A channel again for modification, the alpha color is not visible. (White state)
If I apply again then all attribute A channel values ​​are overwritten with 1.000.

• In summary, the alpha channel painting value is recorded, but the alpha channel is not displayed when working for a certain period of time or when the file is opened again and isolated.
  Since all values ​​are reset when reapplying, it is impossible to preserve or re-modify the existing work values.

*I tested the plan by subdividing it in a new file.
The question is whether this error is affected by the number of objects or vertices in the scene file.

[Andrej730]

Still don't understand what's the issue, can you show some way to reproduce it?

[artechdowon]

https://github.com/user-attachments/assets/8d543386-8b9c-46c5-a0c7-68fe62024791
As you said, if I apply after vertex alpha painting, the values ​​are saved. (Checked through the spreadsheet)
However, if I isolate again for additional modification, I cannot see it. (White state) If I apply again at this time, all values ​​change to 1.
In Blender 3 version, if I isolate again in VCM, the previous work was preserved and displayed.

[Andrej730]

@artechdowon can you reproduce it consistently or it's semi-random?

I'm using Blender 4.3 and couldn't reproduce this:
https://github.com/user-attachments/assets/bcb1293f-40fb-4357-95a6-4ae3232a7b32

[artechdowon]

@Andrej730
This happens quite often. What I want is for the alpha colors I painted before to be preserved and displayed again when I isolate.
The core of my issue is that the alpha channel that I painted before is not displayed again.
If I keep what I did once, there is no problem. If I need to edit it again, I cannot see the previous settings, so I cannot edit it or I have to do it again.
Can you look into this part? And thank you so much for your attention to my issue. I'm sorry if I bothered you too much.

[Andrej730]

This happens quite often.

But not always?

The core of my issue is that the alpha channel that I painted before is not displayed again.
If I keep what I did once, there is no problem. If I need to edit it again, I cannot see the previous settings, so I cannot edit it or I have to do it again.
Can you look into this part? And thank you so much for your attention to my issue. I'm sorry if I bothered you too much.

I couldn't reproduce it (see my demo above), no idea why it happens.
You can check system console (window - toggle system console) for errors when it happens, maybe it'll give us some clues.

[artechdowon]

Here are two demos.
A- When everything is normal, when i isolate Channel Alpha, the values I worked on before are preserved and displayed.
However, this is extremely rare.
Additional fixes are possible.
https://github.com/user-attachments/assets/e317c190-01ce-434f-bac8-92b4789144ae

B- At some point, when I isolate something I worked on again, the previous work is not displayed. (Of course, the alpha value is stored, so I can see it by connecting the alpha channel value to the color in the shader.)
This happens almost 99% of the time.
https://github.com/user-attachments/assets/3630d58a-5025-4140-957d-086076441bdc
What I want is state A.
But most of the time it ends up with the same problem as B.

[Andrej730]

I understand the issue but I've no idea what causing it since I cannot reproduce it.
Is there a way to reproduce it consistently?

Also:

You can check system console (window - toggle system console) for errors when it happens, maybe it'll give us some clues.

[artechdowon]

Yes, it happens pretty consistently.
It switches from A to B within a few minutes of starting Blender.
There was nothing unusual in the system console either.
After isolate, bpy.ops.vertexcolormaster.apply_isolated(discard=False)

After apply,
bpy.ops.vertexcolormaster.isolate_channel(src_channel_id='A')
That's it.

I think the color of the A channel, which should be isolated, is not displayed properly. That's the question.
Even if I reinstall the add-on, the same symptom occurs.

[Andrej730]

It switches from A to B within a few minutes of starting Blender.

There must me some actions during those minutes that's making it transition from A to B, it couldn't be just time Blender running.

There was nothing unusual in the system console either.
After isolate, bpy.ops.vertexcolormaster.apply_isolated(discard=False)

Are you sure you're checking system console and not "Info" panel? System console doesn't typically show executed operators.

[artechdowon]

Almost B state occurs immediately.
State like A is extremely difficult to see.
I was mistaken. The execution statements I uploaded were copied from Info. There was nothing strange about anything else.

[Andrej730]

Almost B state occurs immediately.
State like A is extremely difficult to see.

But why I cannot reproduce it then?

E.g. steps I do:

1. New blender session
2. Start vertex paint mode on the default cube.
3. Isolate Alpha.
4. Paint it.
5. Apply changes.
6. Isolate alpha again.
7. Alpha is okay, has changes from step 4.