hair eevee rendering broken. #70146

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: AMD Radeon HD 7600M Series ATI Technologies Inc. 4.5.13422 Core Profile Context 0

Blender Version
Broken: version: 2.81 (sub 12), branch: master, commit date: 2019-09-21 08:48, hash: ef45d1c8cd
Worked: (optional)

Short description of error
hair eevee rendering brokem.
I don't know if it's a problem related only to my GPU, but, see the gif, the rendering of the hair is adjusted simply by pointing the 3d cursor ...

(I don't know why the system shows this image "this is a mistery" but it is an animated gif, if click on it shows the gif in the right way)

hair_bug.blend

Added subscriber: @nokipaike

I have investigated better and it seems that the problem is not in the hair system, but in the shader, I also checked on the intel HD 4000 and the same problem emerges, so it is not a problem related only to radeon HD, but I think it is a more general problem .

I created a bug test, more simple

hair_test_bug.blend

Added subscriber: @JacquesLucke

Please show how this second test file looks on your machine. (It looks fine for more, seems to be some gpu issue..)

I did a check also on blender 2.80 ...
looks like an "old bug" ..

it seems related to the attributes sometimes
and procedural textures in combination with more complex node shading.
(we must consider that these are shading combinations taken from old blender 2.7x files .. so I wouldn't want it to be a blunder ..)

(the images are both animated gifs)

Added subscriber: @lichtwerk

Havent done any investigation, just noting that I got this:
GPU failed to find function node_bsdf_hair

since it seems a problem of shading and not of hair, I also associate this video, considering that it seems the same problem, this bug has appeared recently with

3a08153d7a and repaired messes on these gpu with d0c772f68b

in the video comparison between blender 2.80 and the latest build of 2.81

mouse.mp4

In #70146#781973, @lichtwerk wrote:
Havent done any investigation, just noting that I got this:
GPU failed to find function node_bsdf_hair

from what I read in Clement's todo, this shader is not yet supported by eevee, so I assume it's normal.

In #70146#781976, @nokipaike wrote:
since it seems a problem of shading and not of hair, I also associate this video, considering that it seems the same problem, this bug has appeared recently with

in the video comparison between blender 2.80 and the latest build of 2.81
.... .. .. (video )

this problem exposed in this last video has been solved by this: a2cc855dba
(probably not the same bug)

"the hair shader bug" is still there

@lichtwerk from this bug report, from that other about the crash of the helicopter b 2.74 scene, and from this post on dev talk
Mapping node backward compatibility
could it be that these are problems related to a no longer compatible node shading system?

Added subscriber: @brecht

Changed status from 'Open' to: 'Archived'

This GPU is below our minimum requirements, and so we no longer provide support for it. The issue is listed in #61936 (EOL GPU problems tracking report) in case anyone wants to work on it.

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hair eevee rendering broken. #70146