EEVEE Next: Wrong normal map node result (tangent space) #114524

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opened 2023-11-06 09:53:29 +01:00 by Yusuf Umar · 4 comments

Yusuf Umar commented

2023-11-06 09:53:29 +01:00

System Information
Operating system: Windows 11
Graphics card: Tested on both RX 6800M & RTX 4090

Blender Version
Broken: Eevee Next (Blender 4.1 Alpha)
Worked: Eevee legacy & Cycles (Any version)

Short description of error
Normal map node produce wrong results when using Eevee next.

Exact steps for others to reproduce the error
Here's the blend file: eevee_next_normal_map_bug.blend

**System Information** Operating system: Windows 11 Graphics card: Tested on both RX 6800M & RTX 4090 **Blender Version** Broken: Eevee Next (Blender 4.1 Alpha) Worked: Eevee legacy & Cycles (Any version) **Short description of error** Normal map node produce wrong results when using Eevee next. ![eevee_next_normal_map_bug.png](/attachments/74997b0a-5be4-4d42-a282-47c7ec28bfa4) **Exact steps for others to reproduce the error** Here's the blend file: [eevee_next_normal_map_bug.blend](/attachments/56912df0-e3e2-4332-8a72-0471c62f4267)

eevee_next_normal_map_bug.png

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eevee_next_normal_map_bug.blend

1.3 MiB

Yusuf Umar added the

labels 2023-11-06 09:53:30 +01:00

Yusuf Umar commented

2023-11-06 10:03:29 +01:00

Author

When debugged using emission shader and standard color management, it will look like this. It looks like eevee next has a problem with the Y axis.

When debugged using emission shader and standard color management, it will look like this. It looks like eevee next has a problem with the Y axis. ![eevee_next_normal_map_bug1.png](/attachments/bfdcfd13-5522-4758-9e04-b80bae42c578)

eevee_next_normal_map_bug1.png

166 KiB

Philipp Oeser commented

2023-11-06 11:07:35 +01:00

Member

Not 100% sure, but seems to be a problem with Tangent Space (Object Space seems to be working as expected).

Will confirm for @fclem / @pragma37 to check

Not 100% sure, but seems to be a problem with Tangent Space (Object Space seems to be working as expected). Will confirm for @fclem / @pragma37 to check

Philipp Oeser changed title from ~~EEVEE Next: Wrong normal map node result~~ to EEVEE Next: Wrong normal map node result (tangent space)

2023-11-06 11:07:47 +01:00

Philipp Oeser added

EEVEE & Viewport

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labels 2023-11-06 11:08:03 +01:00

Enrique-de-la-Calle commented

2023-11-06 21:50:37 +01:00

Contributor

Hello, first time contributor here.

I narrowed down the issue to the sign(ObjectInfo.w) element in the vec3 B term calculation in the file ''gpu_shader_material_normal_map.glsl'' file. In particular, this lines:

[13] vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * sign(ObjectInfo.w);
[19] outnormal = texnormal.x * tangent.xyz + texnormal.y * B + texnormal.z * g_data.Ni;

The main issue is that sign(ObjectInfo.w) is returning zero when ObjectInfo.w itself is zero making the entire binormal calculation to result zero. This shouldn't happen, as the w value is in particular a DRWObjectInfos ob_flag which is possitive or negative, but shouldn't be zero. The sign of this value indicates if there is a negative scaling for calculating the binormal, and because it's used for the Y term of the result normal, the green channel information is wiped out, which is what was mentioned in the previous comments.

I suspect that EEVEE Next unlike EEVEE Legacy, is not populating the ObjectInfo.w value, making it zero by default.

One workaround can be to change in the normal map node file:

vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * sign(ObjectInfo.w);

for

vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * (ObjectInfo.w >= 0.0 ? 1.0 : -1.0);

To contemplate the cases where ObjectInfo.w is zero and set positive sign by default. That been said, such solution wouldn't address the main issue, that is that the negative scaling flag is not being set up properly with EEVEE Next.

I tested the solution I proposed and the results are attached in this comment. The images EEVEE next and EEVEE legacy are almost identical when having normal scaling which is the behaviour expected. The discrepancies appear when setting the Z scale to -1, as Next doesn't have the negative scaling information available and is defaulting as positive instead zero, meanwhile EEVEE Legacy, is correcting the binormal sign properly.

I would like to take this issue as first issue if possible.

Hello, first time contributor here. I narrowed down the issue to the `sign(ObjectInfo.w)` element in the `vec3 B` term calculation in the file ''gpu_shader_material_normal_map.glsl'' file. In particular, this lines: > [13] vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * sign(ObjectInfo.w); > [19] outnormal = texnormal.x * tangent.xyz + texnormal.y * B + texnormal.z * g_data.Ni; The main issue is that `sign(ObjectInfo.w)` is returning zero when `ObjectInfo.w` itself is zero making the entire binormal calculation to result zero. This shouldn't happen, as the `w` value is in particular a `DRWObjectInfos ob_flag` which is possitive or negative, but shouldn't be zero. The sign of this value indicates if there is a negative scaling for calculating the binormal, and because it's used for the Y term of the result normal, the green channel information is wiped out, which is what was mentioned in the previous comments. I suspect that EEVEE Next unlike EEVEE Legacy, is not populating the `ObjectInfo.w` value, making it zero by default. One workaround can be to change in the normal map node file: > vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * sign(ObjectInfo.w); for > vec3 B = tangent.w * cross(g_data.Ni, tangent.xyz) * (ObjectInfo.w >= 0.0 ? 1.0 : -1.0); To contemplate the cases where `ObjectInfo.w` is zero and set positive sign by default. That been said, such solution wouldn't address the main issue, that is that the negative scaling flag is not being set up properly with EEVEE Next. I tested the solution I proposed and the results are attached in this comment. The images EEVEE next and EEVEE legacy are almost identical when having normal scaling which is the behaviour expected. The discrepancies appear when setting the Z scale to -1, as Next doesn't have the negative scaling information available and is defaulting as positive instead zero, meanwhile EEVEE Legacy, is correcting the binormal sign properly. I would like to take this issue as first issue if possible.

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untitled1.png

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Yusuf Umar commented

2023-11-07 06:12:45 +01:00

Author

Hmm, I don't see why eevee next is not populating ObjectInfo.w by design, it's probably just an eevee next bug. Bitangent sign is very crucial to get a proper normal map in tangent space.

Hmm, I don't see why eevee next is not populating `ObjectInfo.w` by design, it's probably just an eevee next bug. Bitangent sign is very crucial to get a proper normal map in tangent space.

Miguel Pozo referenced a pull request that will close this issue

2023-11-07 17:26:41 +01:00

Fix #114524: EEVEE-Next: Wrong normal map node result #114587

Miguel Pozo referenced this issue from a commit

2023-11-07 18:58:40 +01:00

Fix #114524: EEVEE-Next: Wrong normal map node result

Miguel Pozo closed this issue

2023-11-07 18:58:41 +01:00

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