Alpha textures do not work with holdout collection in Eevee #88185

New Issue

Tim Brown Lees · 2021-05-10T18:58:16+02:00

Tim Brown Lees commented

2021-05-10 18:58:16 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92

Blender Version
Broken: version: 2.93.0 Beta, branch: master, commit date: 2021-05-08 23:52, hash: 3c7b80ae2c
Worked: None

Short description of error
When setting a collection to holdout in Eevee, objects with an alpha texture will display as the entire object being held out, but the expected behaviour is possible using a Holdout shader. This can be very inconvenient as then you have to duplicate and remove all models using alpha textures from the collection and create unique materials for them.

The collection set to holdout.

The expected behaviour using a material with alpha blend to hold out the object.

Exact steps for others to reproduce the error

Create an object using an alpha texture (blend mode doesn't seem to matter) in Eevee
Set the collection containing it to holdout

HoldoutAlpha.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92 **Blender Version** Broken: version: 2.93.0 Beta, branch: master, commit date: 2021-05-08 23:52, hash: `3c7b80ae2c` Worked: None **Short description of error** When setting a collection to holdout in Eevee, objects with an alpha texture will display as the entire object being held out, but the expected behaviour is possible using a Holdout shader. This can be very inconvenient as then you have to duplicate and remove all models using alpha textures from the collection and create unique materials for them. ![holdoutcollection.png](https://archive.blender.org/developer/F10076489/holdoutcollection.png) The collection set to holdout. ![holdoutmaterial.png](https://archive.blender.org/developer/F10076492/holdoutmaterial.png) The expected behaviour using a material with alpha blend to hold out the object. **Exact steps for others to reproduce the error** - Create an object using an alpha texture (blend mode doesn't seem to matter) in Eevee - Set the collection containing it to holdout [HoldoutAlpha.blend](https://archive.blender.org/developer/F10076477/HoldoutAlpha.blend)

Tim Brown Lees commented

2021-05-10 18:58:16 +02:00

Added subscriber: @TimBL

Ethan Simon commented

2021-05-10 18:59:23 +02:00

Added subscriber: @razed

Falk David commented

2021-05-11 11:18:48 +02:00

Added subscriber: @filedescriptor

Falk David commented

2021-05-11 11:18:48 +02:00

Not sure if we can call this a bug. This looks to me more like a missing feature since the code is working as intended.

Richard Antalik commented

2021-05-11 19:47:27 +02:00

Added subscribers: @brecht, @iss

Richard Antalik commented

2021-05-11 19:47:27 +02:00

I also think this works as expected.
If anything there may be regression from 2.90 to 2.91 in cycles where collection holdout state doesn't make any difference. @brecht or was that intentional change?

Since 981d7381cd you should get expected result, when collection is not held out. @TimBL isn't this how you made your second image with expected behavior? Because I don't understand why that would be problem, or how shading should other work otherwise when collection is not held out.

I also think this works as expected. If anything there may be regression from 2.90 to 2.91 in cycles where collection holdout state doesn't make any difference. @brecht or was that intentional change? Since 981d7381cd you should get expected result, when collection is **not** held out. @TimBL isn't this how you made your second image with expected behavior? Because I don't understand why that would be problem, or how shading should other work otherwise when collection is not held out.

Brecht Van Lommel commented

2021-05-11 21:46:09 +02:00

Added subscriber: @fclem

Brecht Van Lommel commented

2021-05-11 21:46:09 +02:00

It's up to @fclem to decide if this should be considered a bug or future improvement for Eevee.

In Cycles we changed the behavior to use transparency for holdout objects, which I think is the correct thing to do.

6435acd8f6

It's up to @fclem to decide if this should be considered a bug or future improvement for Eevee. In Cycles we changed the behavior to use transparency for holdout objects, which I think is the correct thing to do. 6435acd8f6

Tim Brown Lees commented

2021-05-11 22:08:11 +02:00

Thanks for the responses, wasn't sure if this was a bug or missing feature.

In #88185#1159378, @iss wrote:
I also think this works as expected.
If anything there may be regression from 2.90 to 2.91 in cycles where collection holdout state doesn't make any difference. @brecht or was that intentional change?

Since 981d7381cd you should get expected result, when collection is not held out. @TimBL isn't this how you made your second image with expected behavior? Because I don't understand why that would be problem, or how shading should other work otherwise when collection is not held out.

I'm not sure I follow. I can attain the result using the 2nd method, but for example: I'm linking in a set to my file that contains a forest with leaves using alpha textures that I want held-out. I now have to go back into the forest blend file, duplicate that collection and assign new materials to it using the holdout shader, then link that in and use it. This can turn a simple task into a bit of a lengthy one if there's a lot of materials with transparency. That has been my solution anyway, maybe theres a better way that I'm just missing!

Thanks for the responses, wasn't sure if this was a bug or missing feature. > In #88185#1159378, @iss wrote: > I also think this works as expected. > If anything there may be regression from 2.90 to 2.91 in cycles where collection holdout state doesn't make any difference. @brecht or was that intentional change? > > Since 981d7381cd you should get expected result, when collection is **not** held out. @TimBL isn't this how you made your second image with expected behavior? Because I don't understand why that would be problem, or how shading should other work otherwise when collection is not held out. I'm not sure I follow. I can attain the result using the 2nd method, but for example: I'm linking in a set to my file that contains a forest with leaves using alpha textures that I want held-out. I now have to go back into the forest blend file, duplicate that collection and assign new materials to it using the holdout shader, then link that in and use it. This can turn a simple task into a bit of a lengthy one if there's a lot of materials with transparency. That has been my solution anyway, maybe theres a better way that I'm just missing!

Philipp Oeser commented

2021-05-12 12:32:48 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-05-12 12:32:48 +02:00

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

Philipp Oeser commented

2021-05-12 12:32:48 +02:00

In #88185#1159433, @brecht wrote:
It's up to @fclem to decide if this should be considered a bug or future improvement for Eevee.

Setting status to "Needs Information from Developers" then.

> In #88185#1159433, @brecht wrote: > It's up to @fclem to decide if this should be considered a bug or future improvement for Eevee. Setting status to "Needs Information from Developers" then.

Clément Foucault commented

2021-05-12 15:05:35 +02:00

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

Clément Foucault commented

2021-05-12 15:05:35 +02:00

I acknowledged that this is a serious workflow isssue. I will consider this as a feature request / TODO.

Evan Wilson commented

2021-07-18 07:21:45 +02:00

Added subscriber: @EAW

Philipp Oeser removed the

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Alpha textures do not work with holdout collection in Eevee #88185