Geometry node don't expose materials to the solidify modifier #95903

New Issue

Alexandre Labedade · 2022-02-20T08:47:13+01:00

2022-02-20 08:47:13 +01:00

System Information
Operating system: Windows 10
Graphics card: Nvidia RTX 2060

Blender Version
Broken: blender-3.1.0-beta+v31.93cc89247010
Worked: 3.0.1

Short description of error

When using a geometry node to generate a mesh, and then applying a solidify modifier to it, the materials are not properly exposed and not or wrongly assigned to the final mesh

Exact steps for others to reproduce the error

create a plane
go in edit mode and delete all the mesh data
back in object mode, add geometry node modifier
add a Cylinder mesh primitive, and set its fill type to None
add a Join Geometry node and plug the Group Input Geometry socket and the Cylinder node Mesh socket into the Join node
plug the join node into the output
add 3 materials to the object and set different colors
add a solidify modifier and set material for offset and rim to indices 1 and 2

The resulting tube doesn't show any of the materials.

go in edit mode and add at least one vertex to the mesh

Now the resulting tube displays the last material of the list on some parts, but this is still not it.

Instead of creating a cylinder in the geometry node tree, plug a Mesh circle primitive
Then add a screw modifier to extrude it, after the geometry node modifier and before the solidify modifier
Set its angle to 0° and Screw value to 1

Now the resulting tube is only displaying the first material

Go in edit mode and add at least one vertex to the mesh

Now the resulting tube displays all the materials properly.

Note : it is not obvious, but it is mandatory to join the original geometry into the end result to get the materials correctly propagated to the output.
Maybe this could be more clearly explained or simplified somehow.

Sample file here reproducing all cases mentionned above :
solidify_material_bug.zip

**System Information** Operating system: Windows 10 Graphics card: Nvidia RTX 2060 **Blender Version** Broken: blender-3.1.0-beta+v31.93cc89247010 Worked: 3.0.1 **Short description of error** When using a geometry node to generate a mesh, and then applying a solidify modifier to it, the materials are not properly exposed and not or wrongly assigned to the final mesh **Exact steps for others to reproduce the error** - create a plane - go in edit mode and delete all the mesh data - back in object mode, add geometry node modifier - add a Cylinder mesh primitive, and set its fill type to None - add a Join Geometry node and plug the Group Input Geometry socket and the Cylinder node Mesh socket into the Join node - plug the join node into the output - add 3 materials to the object and set different colors - add a solidify modifier and set material for offset and rim to indices 1 and 2 The resulting tube doesn't show any of the materials. - go in edit mode and add at least one vertex to the mesh Now the resulting tube displays the last material of the list on some parts, but this is still not it. - Instead of creating a cylinder in the geometry node tree, plug a Mesh circle primitive Then add a screw modifier to extrude it, after the geometry node modifier and before the solidify modifier Set its angle to 0° and Screw value to 1 Now the resulting tube is only displaying the first material - Go in edit mode and add at least one vertex to the mesh Now the resulting tube displays all the materials properly. Note : it is not obvious, but it is mandatory to join the original geometry into the end result to get the materials correctly propagated to the output. Maybe this could be more clearly explained or simplified somehow. Sample file here reproducing all cases mentionned above : [solidify_material_bug.zip](https://archive.blender.org/developer/F12878093/solidify_material_bug.zip)

Alexandre Labedade commented

2022-02-20 08:47:13 +01:00

Added subscriber: @Alesk

Pratik Borhade commented

2022-02-21 03:54:52 +01:00

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

Pratik Borhade commented

2022-02-21 03:54:56 +01:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-02-21 05:14:13 +01:00

Added subscriber: @JacquesLucke

Pratik Borhade commented

2022-02-21 05:14:13 +01:00

I think this got affected in f5ce243a56
@JacquesLucke, can you check?

Not bisected this time but it's actually broke between: b647509913 - 644eb68524

I think this got affected in f5ce243a56 @JacquesLucke, can you check? Not bisected this time but it's actually broke between: b64750991334 - 644eb68524b9

Hans Goudey commented

2022-02-21 20:01:46 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2022-02-21 20:01:46 +01:00

I'm not sure I'd consider this a bug. If the original mesh is empty, I'm not sure it should have an effect on the result. i.e. I think an empty mesh is the same as empty geometry.
At least I think that's the design we've been operating with-- maybe I'm wrong though.

I'm not sure I'd consider this a bug. If the original mesh is empty, I'm not sure it should have an effect on the result. i.e. I think an empty mesh is the same as empty geometry. At least I think that's the design we've been operating with-- maybe I'm wrong though.

Jacques Lucke commented

2022-02-22 16:05:39 +01:00

I find it hard to follow the details of the report. Think that's mainly because it's not entirely clear what the actual and expected behavior is for one very specific example.
In the file some material slots are on the mesh and others on the object, which makes it harder.

Material index propagation when there are no faces using the materials is not guaranteed by the Join Geometry node currently. It could also just drop the unused materials.

Maybe this is related to #95417.

I find it hard to follow the details of the report. Think that's mainly because it's not entirely clear what the actual and expected behavior is for one very specific example. In the file some material slots are on the mesh and others on the object, which makes it harder. Material index propagation when there are no faces using the materials is not guaranteed by the Join Geometry node currently. It could also just drop the unused materials. Maybe this is related to #95417.

Pratik Borhade commented

2022-02-22 16:40:57 +01:00

I find it hard to follow the details of the report.

@JacquesLucke, open .blend file and notice the difference.

3.1.0Beta, master	3.0.1

While in recent versions, adding a single vertex in edit mode displays color on backface.
Test File:
#95903.blend

(note: I haven't seen the file which reporter has attached)

> I find it hard to follow the details of the report. @JacquesLucke, open .blend file and notice the difference. | 3.1.0Beta, master | 3.0.1 | | -- | -- | | ![image.png](https://archive.blender.org/developer/F12882888/image.png) | ![image.png](https://archive.blender.org/developer/F12882891/image.png) | While in recent versions, adding a single vertex in edit mode displays color on backface. Test File: [#95903.blend](https://archive.blender.org/developer/F12882901/T95903.blend) (note: I haven't seen the file which reporter has attached)

Alexandre Labedade commented

2022-02-22 16:53:47 +01:00

In #95903#1311989, @JacquesLucke wrote:
I find it hard to follow the details of the report. Think that's mainly because it's not entirely clear what the actual and expected behavior is for one very specific example.

the expected behavior is to get the solidify modifier give the same result, whether it receives as input a standard mesh or a geometry node result.
In this case the expected result is to have material 0 on the original mesh (before solifidy) and the materials 1 and 2 assigned to the offset and rim parts of the solidify resulting mesh.

In the file some material slots are on the mesh and others on the object, which makes it harder.

During my tests I've put the materials (the 3 of them, in the same order) on the object and on the mesh to see if it could help somehow.
Result : materials on mesh are ignored, only matrerials on objects are effective.

Material index propagation when there are no faces using the materials is not guaranteed by the Join Geometry node currently. It could also just drop the unused materials.

Maybe this is related to #95417.

Yes, it could be related.
If the mesh data or the object are referring to a list of materials, having an empty mesh ( or only some vertices and no faces ) should not be a problem to properly access this list of materials.

> In #95903#1311989, @JacquesLucke wrote: > I find it hard to follow the details of the report. Think that's mainly because it's not entirely clear what the actual and expected behavior is for one very specific example. the expected behavior is to get the solidify modifier give the same result, whether it receives as input a standard mesh or a geometry node result. In this case the expected result is to have material 0 on the original mesh (before solifidy) and the materials 1 and 2 assigned to the offset and rim parts of the solidify resulting mesh. > In the file some material slots are on the mesh and others on the object, which makes it harder. During my tests I've put the materials (the 3 of them, in the same order) on the object and on the mesh to see if it could help somehow. Result : materials on mesh are ignored, only matrerials on objects are effective. > > Material index propagation when there are no faces using the materials is not guaranteed by the Join Geometry node currently. It could also just drop the unused materials. > > Maybe this is related to #95417. Yes, it could be related. If the mesh data or the object are referring to a list of materials, having an empty mesh ( or only some vertices and no faces ) should not be a problem to properly access this list of materials.

Dalai Felinto commented

2022-05-09 11:25:33 +02:00

Added subscriber: @dfelinto

Dalai Felinto commented

2022-05-09 11:25:33 +02:00

Not entirely sure yet that this is a bug, but better to investigate further together with the other material bugs.

Philipp Oeser removed the

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Geometry node don't expose materials to the solidify modifier #95903