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Maniphest T91175

EEVEE - Incorrect cubemap baking with Blend Mode
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Description

  • Using Blender 3.0**

Different/Incorrect results when using a material with Material Alpha set to something below 1.0 and Blend mode set to Alpha Blend.
They also don't include any kind of parallax effect to them.

Upon taking a closer look, i see that the Opaque correct reflection is kept, but for some reason this weird no parallax layer is thrown on top, and is very noticeable, and i think it would make more sense for it to happen when the Alpha is opaque but transmission is set to 1.0, and still have the parallax mapping to mimic refraction.

Opaque ( Or 1.0 alpha ) :


Alpha Blend ( Must have Alpha set to below 1.0 or else it won't bake incorrectly )


Event Timeline

Guilherme Emerich Setúbal (Senhor) created this task.Sep 4 2021, 6:41 AM
Guilherme Emerich Setúbal (Senhor) updated the task description. (Show Details)
Guilherme Emerich Setúbal (Senhor) updated the task description. (Show Details)Sep 4 2021, 6:46 AM
Pratik Borhade (PratikPB2123) added a project: BF Blender.Sep 4 2021, 2:24 PM
Pratik Borhade (PratikPB2123) added a subscriber: Pratik Borhade (PratikPB2123).
Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Needs Information from User.Feb 3 2022, 8:24 PM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).

Revisiting some old reports. Sorry for not replying sooner.
I set up a scene to try to understand the problem, but I'm having trouble understanding which object needs to have the material with "Material Alpha set to something below 1.0 and Blend mode set to Alpha Blend".
My scene apparently renders correctly:


CubeMap_Test.blend17 MBDownload

So, if possible, could you provide a simplified .blend file showing the problem?

Note that to make things easier and avoid mishaps, it is advisable to send the .blend file in the report description (as explained in the submission template and guidelines)
A guideline for making a good bug report can be found at https://wiki.blender.org/wiki/Process/Bug_Reports

Guilherme Emerich Setúbal (Senhor) added a comment.EditedFeb 5 2022, 1:23 AM

Hi, thanks for reminding me about this. After taking a second look i noticed that it is NOT a bug, what happens is that when my material is set to alpha blend 1.0 or opaque, Blender renders it as a solid object, meaning there is no refraction, a black object due to the transmission, however, when i set the alpha blend to a different value, Blender also renders whats behind that object, which obviously makes sense, however, when that cubemap is projected into that same transmissive object, it also projects the refraction which causes that "plane reflection" look.



The solution is to either make it a solid object like i said, or decrease the cubemap clipping end distance. Like i said, is not an issue, its just working as it should. I can't imagine a solution that could be done automatically by Blender and it is not a bug so i think this could be closed, sorry for not doing a more detailed research beforehand.

Germano Cavalcante (mano-wii) closed this task as Archived.Feb 5 2022, 1:59 AM

Thanks for the information. Good to know it's not a bug.
Looking at the last image, this "plane reflection" look of the bookshelf is actually kind of weird.
But maybe it's the position of the probes that need to be adjusted.

Eevee is currently undergoing improvements. It is possible that more options for working with reflection may be implemented in a while ;)

Guilherme Emerich Setúbal (Senhor) added a comment.EditedFeb 5 2022, 7:34 PM

It is really weird, i already tried changing the probe position and it doesnt change much, only solution i can think of is to have an option to always consider the object as "solid" when baking cubemaps, for this case it is better to have no refraction baked, but i can see it being useful for some cases