Geometry Nodes: Random Value node connected to Subdivision Mesh level socket gives error, but still appears to function. #92327

New Issue

Valera Barashkov · 2021-10-19T01:17:04+02:00

Valera Barashkov commented

2021-10-19 01:17:04 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 496.13

Blender Version
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-10-16 12:26, hash: 4a00faca1a
Worked: NA

Short description of error
Random Value node connected to Subdivision Mesh gives error, but still appears to function.
random_val_bug.mp4

Exact steps for others to reproduce the error

subdiv_bug.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 496.13 **Blender Version** Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-10-16 12:26, hash: `4a00faca1a` Worked: NA **Short description of error** Random Value node connected to Subdivision Mesh gives error, but still appears to function. [random_val_bug.mp4](https://archive.blender.org/developer/F11261984/random_val_bug.mp4) **Exact steps for others to reproduce the error** [subdiv_bug.blend](https://archive.blender.org/developer/F11294314/subdiv_bug.blend)

Valera Barashkov commented

2021-10-19 01:17:04 +02:00

Added subscriber: @valera-8

William Leeson commented

2021-10-19 09:27:04 +02:00

Added subscriber: @leesonw

William Leeson commented

2021-10-19 09:27:04 +02:00

Could you add a sample scene to this?

Pratik Borhade commented

2021-10-19 11:03:20 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Pratik Borhade commented

2021-10-19 11:03:26 +02:00

Added subscriber: @PratikPB2123

Valera Barashkov commented

2021-10-19 21:37:50 +02:00

I have added an example file.

Pratik Borhade commented

2021-10-20 11:53:40 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Peter Sergay commented

2021-10-20 18:36:19 +02:00

Added subscriber: @Walnert

Peter Sergay commented

2021-10-20 18:36:19 +02:00

What would you like the fix to be? Since it still works, I think just turning it into a regular line, not a red dotted line, would be a good fix.

Zijun Zhou commented

2021-10-20 20:14:51 +02:00

Added subscriber: @Eary

Zijun Zhou commented

2021-10-20 20:14:51 +02:00

Not quite though. It seems it just converts the field into a single constant value, I think the red line still needs to be there to signal the field does not work here

Hans Goudey commented

2021-10-20 20:19:17 +02:00

Added subscribers: @JacquesLucke, @HooglyBoogly

Hans Goudey commented

2021-10-20 20:19:17 +02:00

The reason the random value node outputs a field in this case is that is has an implicit id/index input (which is also a field). Because the "Level" socket isn't evaluated as a field, that implicit input doesn't work.

Ideally there would be some way for the random value node to not have a field implicit input when it is connected to a single-value (non-field) socket.
@JacquesLucke, do you think that is a reasonable goal?

The reason the random value node outputs a field in this case is that is has an implicit id/index input (which is also a field). Because the "Level" socket isn't evaluated as a field, that implicit input doesn't work. Ideally there would be some way for the random value node to not have a field implicit input when it is connected to a single-value (non-field) socket. @JacquesLucke, do you think that is a reasonable goal?

Jacques Lucke commented

2021-10-20 20:37:19 +02:00

I think we could change the behavior in evaluate_constant_field. If the field has any input, we just return the default value instead of actually evaluating the field.

I think we could change the behavior in `evaluate_constant_field`. If the field has any input, we just return the default value instead of actually evaluating the field.

Valera Barashkov commented

2021-10-21 02:30:34 +02:00

I don't know if there is a point in that since the Random Node will just generate a constant value that user can set from the start without playing with the seed value.

What I need is to somehow have a random seed value that will be randomized just by duplicating the object with the GN modifier, instead of manually changing the group input seed value on each duplicated object if I want to have a slightly different version. This way I can just paint these objects on a surface and have randomly generated geometry right away.

Another solution would be for me to write a script to change the seed values of all the objects I guess..

I don't know if there is a point in that since the Random Node will just generate a constant value that user can set from the start without playing with the seed value. What I need is to somehow have a random seed value that will be randomized just by duplicating the object with the GN modifier, instead of manually changing the group input seed value on each duplicated object if I want to have a slightly different version. This way I can just paint these objects on a surface and have randomly generated geometry right away. Another solution would be for me to write a script to change the seed values of all the objects I guess..

Hans Goudey commented

2021-10-21 16:26:48 +02:00

In #92327#1238799, @JacquesLucke wrote:
I think we could change the behavior in evaluate_constant_field. If the field has any input, we just return the default value instead of actually evaluating the field.

Thanks sounds good to me.

@valera-8, to be clear, fixing this won't give a random-per-object output, that would have to something else, maybe another node.

> In #92327#1238799, @JacquesLucke wrote: > I think we could change the behavior in `evaluate_constant_field`. If the field has any input, we just return the default value instead of actually evaluating the field. Thanks sounds good to me. @valera-8, to be clear, fixing this won't give a random-per-object output, that would have to something else, maybe another node.

Peter Sergay commented

2021-10-22 19:06:34 +02:00

I tested this on a few other nodes, and it looks like it gives a red error-line when you connect the field to any single-number input in the next node. Ex. icosphere radius, all grid node inputs.
It seems like the fix would be to have the field understand when the input it's connected to only wants a single number, then downgrade itself from a field output to a single number output just for that node.

I tested this on a few other nodes, and it looks like it gives a red error-line when you connect the field to any single-number input in the next node. Ex. icosphere radius, all grid node inputs. ![image.png](https://archive.blender.org/developer/F11392906/image.png) It seems like the fix would be to have the field understand when the input it's connected to only wants a single number, then downgrade itself from a field output to a single number output just for that node.

blender-admin commented

2021-10-24 17:53:19 +02:00

This issue was referenced by cc388651eb

This issue was referenced by cc388651eb48e73470c53c185840f74d950cb38d

Jacques Lucke commented

2021-10-24 17:54:04 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Jacques Lucke closed this issue

2021-10-24 17:54:04 +02:00

Jacques Lucke self-assigned this 2021-10-24 17:54:04 +02:00

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Geometry Nodes: Random Value node connected to Subdivision Mesh level socket gives error, but still appears to function. #92327