GPUShader: error: too many samplers in shader. #77240

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Christophe Schollhammer · 2020-05-31T22:18:05+02:00

2020-05-31 22:18:05 +02:00

gpu_error.zip
System Information
Operating system:windows 10
Graphics card:nvidia rtx 2060s

Blender Version
Broken: 2.82, 2.83 ff1040c6fe
Worked: (newest version of Blender that worked as expected)

Short description of error
When in the viewport I want to switch to Material Preview, the object get pink and I get in the console this error
GPUShader: error: too many samplers in shader.

This happen when I add/link too much mixshader or mixrgb node

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).

As this is specific to this file, I attach the file
If you remove one mixshader or one mixrgb it's ok, the preview is fine

[gpu_error.zip](https://archive.blender.org/developer/F8568247/gpu_error.zip) **System Information** Operating system:windows 10 Graphics card:nvidia rtx 2060s **Blender Version** Broken: 2.82, 2.83 ff1040c6fefc Worked: (newest version of Blender that worked as expected) **Short description of error** When in the viewport I want to switch to Material Preview, the object get pink and I get in the console this error GPUShader: error: too many samplers in shader. This happen when I add/link too much mixshader or mixrgb node **Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible). As this is specific to this file, I attach the file If you remove one mixshader or one mixrgb it's ok, the preview is fine

Christophe Schollhammer commented

2020-05-31 22:18:05 +02:00

Added subscriber: @cscholl

Christophe Schollhammer commented

2020-05-31 22:22:01 +02:00

![blender_gpu_error.jpg](https://archive.blender.org/developer/F8568389/blender_gpu_error.jpg)

Silas Opel commented

2020-06-01 00:41:44 +02:00

Added subscriber: @DarkKnight

Silas Opel commented

2020-06-01 00:41:44 +02:00

I think this is intended behavior since its eevee previewing it and a realtime engine has its limits. Maybe someone will corret me but i guess this will get closed as invalid.

Christophe Schollhammer commented

2020-06-01 10:32:38 +02:00

So the Material preview mode is using evee engine ?

Well I have tried with evee renderer to test and it's the same pink render
Hence it would be a limitation of evee ?

So the Material preview mode is using evee engine ? Well I have tried with evee renderer to test and it's the same pink render Hence it would be a limitation of evee ?

Paul Szajner commented

2020-06-02 13:44:45 +02:00

Added subscriber: @sozap

Paul Szajner commented

2020-06-02 13:44:45 +02:00

So the Material preview mode is using evee engine ?

Yes !

Indeed Eevee has some limitations you can't have unlimited textures and or shader nodes inside a material even if yourGPU has enough memory ...
Cycles is also limited but the limitation bar is way higher.

By judging at your screenshot , you can rework you shader to have only one or a few principled nodes : mixing colors instead of mixing shaders . That would make the shader to run faster and it may solve your limitation issue.
https://blenderartists.org/t/mixing-multiples-shaders-in-eevee/1173843/3

I also think this report is more a known limitation rather than a bug...

> So the Material preview mode is using evee engine ? Yes ! Indeed Eevee has some limitations you can't have unlimited textures and or shader nodes inside a material even if yourGPU has enough memory ... Cycles is also limited but the limitation bar is way higher. By judging at your screenshot , you can rework you shader to have only one or a few principled nodes : mixing colors instead of mixing shaders . That would make the shader to run faster and it may solve your limitation issue. https://blenderartists.org/t/mixing-multiples-shaders-in-eevee/1173843/3 I also think this report is more a known limitation rather than a bug...

Jeroen Bakker commented

2020-06-02 15:00:19 +02:00

Added subscriber: @Jeroen-Bakker

Jeroen Bakker commented

2020-06-02 15:00:19 +02:00

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

Jeroen Bakker closed this issue

2020-06-02 15:00:19 +02:00

Jeroen Bakker self-assigned this 2020-06-02 15:00:19 +02:00

Jeroen Bakker commented

2020-06-02 15:00:19 +02:00

This is a hardware limit. The used shader tree uses too many textures that isn't supported by the OpenGL Hardware it is rendering on. Try reducing the number of used textures. Or split your mesh to use multiple materials that only use a subset of the all the needed textures. Or Combine several mask images into a single mask image (store each mask in a single channel).

Christophe Schollhammer commented

2020-06-02 15:43:10 +02:00

Ok I have to rethink the way I'm using shaders as it is far from being optimised ;)
Thanks a lot for the advices Paul & Jeroen

Ok I have to rethink the way I'm using shaders as it is far from being optimised ;) Thanks a lot for the advices Paul & Jeroen

Christophe Schollhammer commented

2020-06-02 19:19:19 +02:00

I have tried to use mixRGB nodes instead of mixshader nodes so I have replaced 3 mixshader nodes by 3 mixrgb nodes but I still have this problem
Is it normal ?
I must precise that I'm using udim textures
Thanks

I have tried to use mixRGB nodes instead of mixshader nodes so I have replaced 3 mixshader nodes by 3 mixrgb nodes but I still have this problem Is it normal ? I must precise that I'm using udim textures Thanks

Paul Szajner commented

2020-06-03 22:49:14 +02:00

Hello, you should ask these kind of question into related forums such as BlenderArtists.org, the bug tracker should be only used to report bugs...

Andrea commented

2021-03-20 08:16:33 +01:00

Added subscriber: @Andrew_D-1

Andrea commented

2021-03-20 08:16:33 +01:00

This limitation occurs in Eevee when trying to use 24 different images or more in the same material.
Exactly that happens, "Purple" material and message "GPUShader: error: too many samplers in shader."
It is a known limitation in Eevee

This limitation occurs in Eevee when trying to use 24 different images or more in the same material. Exactly that happens, "Purple" material and message "GPUShader: error: too many samplers in shader." It is a known limitation in Eevee

James Baber commented

2021-12-16 18:25:55 +01:00

Added subscriber: @JamesBaber

James Baber commented

2021-12-16 18:25:55 +01:00

Currently working on a metahuman face importer for blender, and this seems to be where I have hit a wall. I need a material that can blend between 42 different image inputs, plus 3 image inputs are need for the base material totaling to 45 needed image inputs to support all expressions . So to avoid breaking my shader at the moment, I cap the image inputs to 23 to stay under the 24th image that breaks the shader entirely, so some animated maps are missing in the facial expressions.

Why is 24 the limit? It seems a little strange to me that this is a hard number, since I would imagine it would be dynamic based on your systems GPU memory. Any thoughts?

Currently working on a metahuman face importer for blender, and this seems to be where I have hit a wall. I need a material that can blend between 42 different image inputs, plus 3 image inputs are need for the base material totaling to 45 needed image inputs to support all expressions . So to avoid breaking my shader at the moment, I cap the image inputs to 23 to stay under the 24th image that breaks the shader entirely, so some animated maps are missing in the facial expressions. Why is 24 the limit? It seems a little strange to me that this is a hard number, since I would imagine it would be dynamic based on your systems GPU memory. Any thoughts?

Jeroen Bakker commented

2021-12-17 08:39:07 +01:00

@JamesBaber software runs on hardware. hardware drives limitations.

For sampling textures GPU manufacturers add specialized silicon for performance reasons (TMU). This silicon has to be setup before a draw call and cannot be changed during a draw call. In your case you can think atlas textures, channel remapping or delta mapping to reduce the number of samplers.

I can imagine unreal engine uses texture arrays to overcome the limitation that should be fast for this specific case. Using similar approaches in Eevee needs to be carefully designed as it could lead to lesser overall performance due to cache invalidation.

@JamesBaber software runs on hardware. hardware drives limitations. For sampling textures GPU manufacturers add specialized silicon for performance reasons (TMU). This silicon has to be setup before a draw call and cannot be changed during a draw call. In your case you can think atlas textures, channel remapping or delta mapping to reduce the number of samplers. I can imagine unreal engine uses texture arrays to overcome the limitation that should be fast for this specific case. Using similar approaches in Eevee needs to be carefully designed as it could lead to lesser overall performance due to cache invalidation.

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GPUShader: error: too many samplers in shader. #77240