eevee: mix holdout with transparent fails #77069

New Issue

paul simon heyduck · 2020-05-26T02:25:45+02:00

paul simon heyduck commented

2020-05-26 02:25:45 +02:00

mixing holdout with transparent in an eevee shader nodes behaves unexpected.

reproduce:
holdout and transparent in a mix node.

it looks like the transparent bsdf is blending into black while bekoming alpha-ed out.
the material blendmode is "alpha blend". but other material blendmodes dont work aswell.

on 0.5 mixed, the holdout is half there, as expected, but transparent looks like color(0.5,0.5,0.5,0.5)

solution?
i assume, its internally blending to color(0,0,0,0) but the transparent needs (1,1,1,n) to stay invisible, and in this case should be at color(1,1,1,0.5) when 0.5 mixed.
(since it seems to not use the alpha information internaly and, if my assumption is correct, holdout just is alpha and doesnt need its own color data)

so for the transition it might work correct if holdout takes rgb from the material to be mixed with.
or maybe give the holdout node an rgb input for mixing situations.

i hope that helps somehow :)

eevee transparent vs holdout.blend

System Information
Operating system: Windows-10-10.0.17763-SP0 64 Bits
Graphics card: GeForce GTX 980M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20

Blender Version
Broken: version: 2.83 (sub 17), branch: master, commit date: 2020-05-24 19:03, hash: 0d0df683d9
Worked: nope, ...this is all just so new to eevee <3

**mixing holdout with transparent in an eevee shader nodes behaves unexpected.** **reproduce:** holdout and transparent in a mix node. - it looks like the transparent bsdf is blending into black while bekoming alpha-ed out. - the material blendmode is "alpha blend". but other material blendmodes dont work aswell. on 0.5 mixed, the holdout is half there, as expected, but transparent looks like color(0.5,0.5,0.5,0.5) **solution?** i assume, its internally blending to color(0,0,0,0) but the transparent needs (1,1,1,n) to stay invisible, and in this case should be at color(1,1,1,0.5) when 0.5 mixed. (since it seems to not use the alpha information internaly and, if my assumption is correct, holdout just is alpha and doesnt need its own color data) - so for the transition it might work correct if holdout takes rgb from the material to be mixed with. - or maybe give the holdout node an rgb input for mixing situations. i hope that helps somehow :) [eevee transparent vs holdout.blend](https://archive.blender.org/developer/F8554381/eevee_transparent_vs_holdout.blend) **System Information** Operating system: Windows-10-10.0.17763-SP0 64 Bits Graphics card: GeForce GTX 980M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20 **Blender Version** Broken: version: 2.83 (sub 17), branch: master, commit date: 2020-05-24 19:03, hash: `0d0df683d9` Worked: nope, ...this is all just so new to eevee <3

paul simon heyduck commented

2020-05-26 02:25:45 +02:00

Added subscriber: @PaulHeyduck

Richard Antalik commented

2020-05-27 14:54:58 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-05-27 14:54:58 +02:00

Changed status from 'Needs Triage' to: 'Archived'

Richard Antalik closed this issue

2020-05-27 14:54:58 +02:00

Richard Antalik self-assigned this 2020-05-27 14:54:58 +02:00

Richard Antalik commented

2020-05-27 14:54:58 +02:00

To my knowledge this is working as it is supposed - holdout shader will not "pass" any data through therefore it will be completely black. Unfortunately I am not able to provide "workaround" for this case, but please try asking on forums for help, or propose new features on appropriate portals.

Issue reported here is a request for modified/improved behavior and not a bug in current behavior. Closing as this bug tracker is only for bugs and errors.

For user requests and feedback, please use other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests
For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug

For help using Blender, please try one of the community websites: https://www.blender.org/community/

To my knowledge this is working as it is supposed - holdout shader will not "pass" any data through therefore it will be completely black. Unfortunately I am not able to provide "workaround" for this case, but please try asking on forums for help, or propose new features on appropriate portals. Issue reported here is a request for modified/improved behavior and not a bug in current behavior. Closing as this bug tracker is only for bugs and errors. For user requests and feedback, please use other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug For help using Blender, please try one of the community websites: https://www.blender.org/community/

paul simon heyduck commented

2020-05-27 17:48:38 +02:00

posted this on rightclick select.
i still think its a bug.
in cycles its working like it should and since cycles and eevee should behave more or less the same, i hope it actually valid.

posted this on rightclick select. i still think its a bug. in cycles its working like it should and since cycles and eevee should behave more or less the same, i hope it actually valid. ![transparency fail3.jpg](https://archive.blender.org/developer/F8558087/transparency_fail3.jpg)

Clément Foucault commented

2020-05-28 15:47:52 +02:00

Changed status from 'Archived' to: 'Confirmed'

Clément Foucault reopened this issue

2020-05-28 15:47:52 +02:00

blender-admin commented

2020-06-30 21:12:32 +02:00

This issue was referenced by 981d7381cd

This issue was referenced by 981d7381cd27432616c69d63cfaeb16aff6d3edb

Clément Foucault commented

2020-06-30 21:12:49 +02:00

Changed status from 'Confirmed' to: 'Resolved'