color type alpha channel not yet implemented (for attribute mix node) #89795

New Issue

Laureline Amerio · 2021-07-11T18:03:24+02:00

Laureline Amerio commented

2021-07-11 18:03:24 +02:00

Hello

It seems that the attribute mix node do not mix alpha's properly, for example, when mixing a color with alpha of 1 and color with alpha of 0, no interpolation is done, therefore the result is not accurate (same for every other caclulation method it seems)

Overall the 4th channel of this color vector type is straight out ignored during the calculation and i believe that this attribute mix node did not implemented the color type properly?

On a side note: there's missing RGBA to color and color to RGBA attribute separate node, therefore, for the time being, this 4th channel is impossible to access properly, but i suppose this will be adressed shortly with the new attribute field proposal is implemented?

Here's an example of the issue, tested on latest 3.0 alha build

Hello It seems that the attribute mix node do not mix alpha's properly, for example, when mixing a color with alpha of 1 and color with alpha of 0, no interpolation is done, therefore the result is not accurate (same for every other caclulation method it seems) Overall the 4th channel of this color vector type is straight out ignored during the calculation and i believe that this attribute mix node did not implemented the color type properly? On a side note: there's missing RGBA to color and color to RGBA attribute separate node, therefore, for the time being, this 4th channel is impossible to access properly, but i suppose this will be adressed shortly with the new attribute field proposal is implemented? Here's an example of the issue, tested on latest 3.0 alha build ![xxxxjpg.jpg](https://archive.blender.org/developer/F10220603/xxxxjpg.jpg)

Laureline Amerio commented

2021-07-11 18:03:24 +02:00

Added subscriber: @mynameisokp

Laureline Amerio changed title from ~~color alpha channel not yet implemented for attribute mix node~~ to color type alpha channel not yet implemented (for attribute mix node)

2021-07-11 18:14:30 +02:00

Pratik Borhade commented

2021-07-12 12:50:34 +02:00

Added subscriber: @PratikPB2123

Philipp Oeser commented

2021-07-12 15:06:29 +02:00

Added subscribers: @JacquesLucke, @lichtwerk

Philipp Oeser commented

2021-07-12 15:06:29 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2021-07-12 15:06:29 +02:00

Well, I can confirm, it is always using ramp_blend in MA_RAMP_BLEND mode since the introduction in d72ec16e70.

@JacquesLucke : should we be using blend_color_XXX instead? (like we do for CustomDataLayers)? These seem to support similar blend modes (and take alpha into account properly).
If so, I could look into making that change...

Well, I can confirm, it is always using `ramp_blend` in `MA_RAMP_BLEND` mode since the introduction in d72ec16e70. @JacquesLucke : should we be using `blend_color_XXX` instead? (like we do for CustomDataLayers)? These seem to support similar blend modes (and take alpha into account properly). If so, I could look into making that change...

Jacques Lucke commented

2021-07-12 16:37:57 +02:00

Wonder what shader and compositor nodes are using. Generally, I'm not opposed to using blend_color_xxx, haven't looked into it in detail now.

Wonder what shader and compositor nodes are using. Generally, I'm not opposed to using `blend_color_xxx`, haven't looked into it in detail now.

Hans Goudey commented

2021-07-20 22:10:12 +02:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2021-07-20 22:10:12 +02:00

I think the change makes sense. It also means we could refactor the node to avoid the switch statement for the blend type on every single loop iteration. Are you still interested in doing that @lichtwerk? I could do it otherwise.

Hans Goudey commented

2021-07-21 03:06:26 +02:00

Actually, looking at this other set of functions, it seems they also don't do what we want, since they use the alpha value of the second color for mixing instead of a separate float factor.

Philipp Oeser commented

2021-07-21 10:01:59 +02:00

@HooglyBoogly : probably wont have time short-term, so go ahead.

Borek Bures commented

2021-11-17 19:26:11 +01:00

Added subscriber: @BorekBures

Borek Bures commented

2021-11-17 19:26:11 +01:00

Until this will be fixed, here is a small workaround. If you keep the alpha separate from the color, you can mix it separately and merge it back into the RGBA color using these nodes.

Until this will be fixed, here is a small workaround. If you keep the alpha separate from the color, you can mix it separately and merge it back into the RGBA color using these nodes. ![RGBA.jpg](https://archive.blender.org/developer/F11820432/RGBA.jpg)

Jacques Lucke commented

2021-11-19 11:15:42 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Archived'

Jacques Lucke closed this issue

2021-11-19 11:15:42 +01:00

Jacques Lucke commented

2021-11-19 11:15:42 +01:00

Will close this because the node used in the original report is deprecated. A new report could be created. I'm not entirely sure how this should be fixed without possibly breaking existing files.

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color type alpha channel not yet implemented (for attribute mix node) #89795