Eevee Attribute Rendering Has Some Left Out Nodes Comparing with Cycles #93179

New Issue

Zijun Zhou · 2021-11-18T03:55:14+01:00

Zijun Zhou commented

2021-11-18 03:55:14 +01:00

System Information
Operating system: Windows-10-10.0.19042-SP0 64 Bits
Graphics card: NVIDIA GeForce MX130/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 496.49

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-11-18 00:40, hash: ceec400975
Worked: none

Short description of error
It seems it's forgotten that Vertext Color node and UV Map node can also read generic attributes, at least Cycles reads it. The fact that Eevee doesn't should be considered a bug.

Exact steps for others to reproduce the error
Turn on Rendered View Shading on the Left Side Viewport and Comapre Cycles and Eevee Results.
Eevee Attribute Rendering Has Some Left Out Nodes Comparing with Cycles.blend

**System Information** Operating system: Windows-10-10.0.19042-SP0 64 Bits Graphics card: NVIDIA GeForce MX130/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 496.49 **Blender Version** Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-11-18 00:40, hash: `ceec400975` Worked: none **Short description of error** It seems it's forgotten that `Vertext Color` node and `UV Map` node can also read generic attributes, at least Cycles reads it. The fact that Eevee doesn't should be considered a bug. ![image.png](https://archive.blender.org/developer/F11821932/image.png) **Exact steps for others to reproduce the error** Turn on Rendered View Shading on the Left Side Viewport and Comapre Cycles and Eevee Results. [Eevee Attribute Rendering Has Some Left Out Nodes Comparing with Cycles.blend](https://archive.blender.org/developer/F11821939/Eevee_Attribute_Rendering_Has_Some_Left_Out_Nodes_Comparing_with_Cycles.blend)

Zijun Zhou commented

2021-11-18 03:55:14 +01:00

Added subscriber: @Eary

Pratik Borhade commented

2021-11-18 06:52:04 +01:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-11-18 07:08:23 +01:00

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

Pratik Borhade commented

2021-11-18 07:08:23 +01:00

Hi, thanks for the report. I can reproduce this issue on master.

For now, Issue can be fixed by using Attribute node instead of specific nodes.

Hi, thanks for the report. I can reproduce this issue on master. For now, Issue can be fixed by using `Attribute node` instead of specific nodes.

Brecht Van Lommel commented

2021-11-18 15:23:03 +01:00

Added subscribers: @kevindietrich, @brecht

Brecht Van Lommel commented

2021-11-18 15:23:03 +01:00

CC @kevindietrich.

Kévin Dietrich commented

2021-11-19 15:35:30 +01:00

Is this even a bug? The UV map (CD_MLOOPUV/CD_MTFACE) is being overwritten by a point attribute (with CD_PROP_FLOAT3 type here) so the attribute lookup fails as the UV Map node is requesting a CD_MTFACE (similarly for the vertex color). We could use CD_AUTO_FROM_NAME in the UV Map and Vertex Color nodes to avoid further complicating the attribute lookup logic in the render code, which will fix the issue. But overwriting such standard attributes in Blender is going to make exporters (like Alembic or USD) fail.

Cycles works here because it just requests the attribute by name, with no type constraint.

Is this even a bug? The UV map (`CD_MLOOPUV`/`CD_MTFACE`) is being overwritten by a point attribute (with `CD_PROP_FLOAT3` type here) so the attribute lookup fails as the UV Map node is requesting a `CD_MTFACE` (similarly for the vertex color). We could use `CD_AUTO_FROM_NAME` in the UV Map and Vertex Color nodes to avoid further complicating the attribute lookup logic in the render code, which will fix the issue. But overwriting such standard attributes in Blender is going to make exporters (like Alembic or USD) fail. Cycles works here because it just requests the attribute by name, with no type constraint.

Brecht Van Lommel commented

2021-11-22 18:32:02 +01:00

It could be argued this is a bug in Cycles, though solving it there does not really make it easier for users to set up correct shaders for geometry nodes. As far as I can tell the downside of CD_AUTO_FROM_NAME would be cases where UV maps and vertex loops have the same name. Though Cycles also has that and I think we might as well make it consistent.

In #93179#1256385, @kevindietrich wrote:
We could use CD_AUTO_FROM_NAME in the UV Map and Vertex Color nodes to avoid further complicating the attribute lookup logic in the render code, which will fix the issue. But overwriting such standard attributes in Blender is going to make exporters (like Alembic or USD) fail.

It's not clear to me how Alembic and USD are related to this bug. Are you saying that changing the shader nodes would have some negative impact on them? Or that the fact that geometry nodes write to general attributes instead of UV maps and vertex colors is a problem independent of this, and that we should address that as the root cause instead or in addition to this?

If so, I think we should make the shading nodes consistent regardless. The geometry nodes team is aware of the interop issues between general attributes and UV maps and vertex colors, though I'm not sure if there is a concrete plan to tackle that.

It could be argued this is a bug in Cycles, though solving it there does not really make it easier for users to set up correct shaders for geometry nodes. As far as I can tell the downside of `CD_AUTO_FROM_NAME` would be cases where UV maps and vertex loops have the same name. Though Cycles also has that and I think we might as well make it consistent. > In #93179#1256385, @kevindietrich wrote: > We could use `CD_AUTO_FROM_NAME` in the UV Map and Vertex Color nodes to avoid further complicating the attribute lookup logic in the render code, which will fix the issue. But overwriting such standard attributes in Blender is going to make exporters (like Alembic or USD) fail. It's not clear to me how Alembic and USD are related to this bug. Are you saying that changing the shader nodes would have some negative impact on them? Or that the fact that geometry nodes write to general attributes instead of UV maps and vertex colors is a problem independent of this, and that we should address that as the root cause instead or in addition to this? If so, I think we should make the shading nodes consistent regardless. The geometry nodes team is aware of the interop issues between general attributes and UV maps and vertex colors, though I'm not sure if there is a concrete plan to tackle that.

Kévin Dietrich commented

2022-01-04 11:53:38 +01:00

In #93179#1258121, @brecht wrote:
It's not clear to me how Alembic and USD are related to this bug. Are you saying that changing the shader nodes would have some negative impact on them? Or that the fact that geometry nodes write to general attributes instead of UV maps and vertex colors is a problem independent of this, and that we should address that as the root cause instead or in addition to this?

I meant the latter, but I was thinking out loud mostly. My two statements were not meant to follow logically each other. I realized while looking into this that changing the UV maps type information with geometry nodes that exporting UV maps will fail in Alembic as it looks for a CD_MLOOPUV of the same name (CD_PROP_FLOAT2 could work, but even that is not well supported by geometry nodes currently).

> In #93179#1258121, @brecht wrote: > It's not clear to me how Alembic and USD are related to this bug. Are you saying that changing the shader nodes would have some negative impact on them? Or that the fact that geometry nodes write to general attributes instead of UV maps and vertex colors is a problem independent of this, and that we should address that as the root cause instead or in addition to this? I meant the latter, but I was thinking out loud mostly. My two statements were not meant to follow logically each other. I realized while looking into this that changing the UV maps type information with geometry nodes that exporting UV maps will fail in Alembic as it looks for a `CD_MLOOPUV` of the same name (`CD_PROP_FLOAT2` could work, but even that is not well supported by geometry nodes currently).

blender-admin commented

2022-05-03 22:45:27 +02:00

This issue was referenced by 281bcc1c1d

This issue was referenced by 281bcc1c1dd6b786bafa2712986885c44ed482a3

Kévin Dietrich commented

2022-05-03 22:50:38 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Kévin Dietrich closed this issue

2022-05-03 22:50:38 +02:00

Kévin Dietrich self-assigned this 2022-05-03 22:50:38 +02:00

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Eevee Attribute Rendering Has Some Left Out Nodes Comparing with Cycles #93179