Geonodes can't be applied on top of Multires while the displace modifier can be applied #104262

New Issue

kursad k · 2023-01-31T19:36:09+01:00

kursad k commented

2023-01-31 19:36:09 +01:00

System Information
Operating system: Windows

Blender Version
Broken: 11de4aa0ce

Short description of error

When the user applies a geonodes modifier that displaces the vertices, it is applied to the base mesh while a displacement modifier can be applied on top of a multires modifier. This is an important use case, and we should retain the ability to applying modifiers on top of the Multires modifier if the displacement modifier is discarded in the future in favor of the geonodes setups.

blender_JB98dYc2yb.mp4

Exact steps for others to reproduce the error

Load the attached .blend

Apply the displacement modifier

Undo

Apply the geo nodes

Observe the difference.

_31012023_1225_17.zip

**System Information** Operating system: Windows **Blender Version** Broken: 11de4aa0cea7 **Short description of error** When the user applies a geonodes modifier that displaces the vertices, it is applied to the base mesh while a displacement modifier can be applied on top of a multires modifier. This is an important use case, and we should retain the ability to applying modifiers on top of the Multires modifier if the displacement modifier is discarded in the future in favor of the geonodes setups. [blender_JB98dYc2yb.mp4](https://archive.blender.org/developer/F14223273/blender_JB98dYc2yb.mp4) **Exact steps for others to reproduce the error** Load the attached .blend Apply the displacement modifier Undo Apply the geo nodes Observe the difference. [_31012023_1225_17.zip](https://archive.blender.org/developer/F14223330/_31012023_1225_17.zip)

kursad k commented

2023-01-31 19:36:10 +01:00

Added subscriber: @kursadk

Iliya Katushenock commented

2023-01-31 19:47:03 +01:00

Added subscriber: @mod_moder

Iliya Katushenock commented

2023-01-31 19:47:03 +01:00

Hello. There are several groups of modifiers. these are the columns in the add modifier menu. And it has real technical limitations.
Generation modifiers mean exactly that they can't just deform something.
2023-01-31 21-45-20.mp4

Hello. There are several groups of modifiers. these are the columns in the add modifier menu. And it has real technical limitations. Generation modifiers mean exactly that they can't just deform something. [2023-01-31 21-45-20.mp4](https://archive.blender.org/developer/F14223495/2023-01-31_21-45-20.mp4)

kursad k commented

2023-01-31 21:00:09 +01:00

@mod_moder I understand that but bear in mind I am only displacing points not generating new geometry or messing with the polygon data. It is basically doing what a displace modifier does, see the image.

@mod_moder I understand that but bear in mind I am only displacing points not generating new geometry or messing with the polygon data. It is basically doing what a displace modifier does, see the image. ![blender_zsCSKm1XKu.jpg](https://archive.blender.org/developer/F14223724/blender_zsCSKm1XKu.jpg)

Iliya Katushenock commented

2023-01-31 21:07:19 +01:00

It is too difficult to check this in the general case. Geometry nodes are just a generator.

ronan ducluzeau commented

2023-02-02 12:30:26 +01:00

Added subscriber: @zeauro

ronan ducluzeau commented

2023-02-02 12:30:26 +01:00

Geometry Nodes can be used as Deform modifiers, as much as Generate modifiers.

So, user should have both options.

There could be a check to know if polycount have been changed by modifier.
In that case, Apply option would apply on base mesh like a Generate modifier.
If there is no change of polycount, Apply option would apply on multires level like a Deform modifier.

If it is too complicated to have an automatic check, or if there is a fear of case of a generation done with a decimation, giving same polycount ; choice could be given to the user.
There could be an Apply as Multires Level option like there is an Apply as Shape Key option, only available for Deform modifier.
That solution would have advantage to be more discoverable than apply-on-level-below-the-highest-one trick working, when an attempt of an apply-on-highest-level triggers a pop-up message, saying that is not possible.

Geometry Nodes could be an exception in Generate modifiers list and could support these options.

Geometry Nodes can be used as Deform modifiers, as much as Generate modifiers. So, user should have both options. There could be a check to know if polycount have been changed by modifier. In that case, Apply option would apply on base mesh like a Generate modifier. If there is no change of polycount, Apply option would apply on multires level like a Deform modifier. If it is too complicated to have an automatic check, or if there is a fear of case of a generation done with a decimation, giving same polycount ; choice could be given to the user. There could be an Apply as Multires Level option like there is an Apply as Shape Key option, only available for Deform modifier. That solution would have advantage to be more discoverable than apply-on-level-below-the-highest-one trick working, when an attempt of an apply-on-highest-level triggers a pop-up message, saying that is not possible. Geometry Nodes could be an exception in Generate modifiers list and could support these options.

Iliya Katushenock commented

2023-02-02 12:32:24 +01:00

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

Iliya Katushenock closed this issue

2023-02-02 12:32:24 +01:00

Julien Kaspar commented

2023-02-03 14:37:55 +01:00

Added subscriber: @JulienKaspar

Julien Kaspar commented

2023-02-03 14:37:55 +01:00

@kursadk @zeauro This is noted down as an important use case for the future multires rewrite, also in relation to #101778.
Multires needs to become more accessible for other parts of Blender and there are already discussions on integrating it with geometry nodes.
But this is outside of the scope of the current projects and not a bug.

@kursadk @zeauro This is noted down as an important use case for the future multires rewrite, also in relation to #101778. Multires needs to become more accessible for other parts of Blender and there are already discussions on integrating it with geometry nodes. But this is outside of the scope of the current projects and not a bug.

Hans Goudey commented

2023-02-03 14:46:46 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2023-02-03 14:46:46 +01:00

there are already discussions on integrating it with geometry nodes

Interesting, is anything written down on that topic? I wasn't aware people were thinking about that.

>there are already discussions on integrating it with geometry nodes Interesting, is anything written down on that topic? I wasn't aware people were thinking about that.

kursad k commented

2023-02-03 22:47:37 +01:00

@JulienKaspar Thanks for the additional information and attention to this bug.

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Geonodes can't be applied on top of Multires while the displace modifier can be applied #104262