Grease Pencil modifier "line art" won't draw objects with Geometry Nodes Instances. #98424

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Luciano Muñoz Sessarego · 2022-05-27T08:30:11+02:00

2022-05-27 08:30:11 +02:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2070 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.96

Blender Version
Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-05-25 21:21, hash: dc6fe73e70

Worked: Blender 3.2

Short description of error
Grease Pencil modifier "line art" won't draw objects with Geometry Nodes Instances.

Exact steps for others to reproduce the error

New scene.
Keep the cube.
Don't delete it.
Add an empty Grease Pencil Object.
Don't delete the cube.
Add a Line Art Modifier to the Grease Pencil Object,
Switch Source to Object, and select the cube.
Assign the default layer and material.
You should be seeing something like this

Add geometry nodes nodes to the cube.
yes keep the damn cube.
here is the simplest setup that involves instances that I could think of

as you can see in the viewport the grease pencil line art has dissapeared completely.

Thanks for looking into it.

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2070 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.96 **Blender Version** Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-05-25 21:21, hash: `dc6fe73e70` ![image.png](https://archive.blender.org/developer/F13113035/image.png) Worked: Blender 3.2 ![image.png](https://archive.blender.org/developer/F13113043/image.png) **Short description of error** Grease Pencil modifier "line art" won't draw objects with Geometry Nodes Instances. **Exact steps for others to reproduce the error** - New scene. - Keep the cube. - Don't delete it. - Add an empty Grease Pencil Object. - Don't delete the cube. - Add a Line Art Modifier to the Grease Pencil Object, - Switch Source to Object, and select the cube. - Assign the default layer and material. - You should be seeing something like this ![image.png](https://archive.blender.org/developer/F13113050/image.png) - Add geometry nodes nodes to the cube. - yes keep the damn cube. - here is the simplest setup that involves instances that I could think of ![image.png](https://archive.blender.org/developer/F13113055/image.png) - as you can see in the viewport the grease pencil line art has dissapeared completely. Thanks for looking into it.

Luciano Muñoz Sessarego commented

2022-05-27 08:30:11 +02:00

Added subscriber: @LucianoMunoz

Aleš Jelovčan commented

2022-05-27 08:34:36 +02:00

Added subscriber: @frogstomp-4

Aleš Jelovčan commented

2022-05-27 08:34:36 +02:00

@LucianoMunoz try adding "realize instances" node before output

@LucianoMunoz try adding "realize instances" node before output ![image.png](https://archive.blender.org/developer/F13113071/image.png)

Luciano Muñoz Sessarego commented

2022-05-27 08:54:14 +02:00

Yes that works, thanks !
but that's not the point tho. :)

Yes that works, thanks ! but that's not the point tho. :)

Aleš Jelovčan commented

2022-05-27 09:26:34 +02:00

@LucianoMunoz this is expected behaviour. You need to use realize instances also if you want to use modifiers on geometry nodes outputs.

Bevel modifier in this case would not produce any effect if you didn't use realize instances.

@LucianoMunoz this is expected behaviour. You need to use realize instances also if you want to use modifiers on geometry nodes outputs. Bevel modifier in this case would not produce any effect if you didn't use realize instances. ![image.png](https://archive.blender.org/developer/F13113165/image.png)

Omar Emara commented

2022-05-27 09:26:53 +02:00

Added subscribers: @ChengduLittleA, @OmarEmaraDev

Omar Emara commented

2022-05-27 09:26:53 +02:00

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

Omar Emara commented

2022-05-27 09:26:53 +02:00

@ChengduLittleA Not sure if this is due to a change in LineArt or GN? Let me know if you want me to bisect.

Omar Emara commented

2022-05-27 09:29:28 +02:00

@frogstomp-4 I think the point is that it used to work up until recently, so it is not an intrinsic limitation.

YimingWu self-assigned this 2022-05-27 09:43:15 +02:00

YimingWu commented

2022-05-27 09:43:15 +02:00

Hi! This is due to a recent change in how line art loads objects (which is still wrong but we don't have a viable way in terms of depsgraph usage, basically we can't actually iterate objects and instance during line art evaluation). I'm not that familiar with depsgraph to present a very solid solution for it, but there will be a solution to come.

I actually want to revert back to the original object iterator since that's how line art has been doing stuff all this time, though it's incorrect and theoretically could cause access conflicts in depsgraph, we actually didn't have any(?) bug reports regarding line art crashes that's determined to be caused by this, and I myself haven't experienced this sort of crashes either (which is probably why I or GP guys never knew the way we are doing stuff is technically wrong).

Hi! This is due to a recent change in how line art loads objects (which is still wrong but we don't have a viable way in terms of depsgraph usage, basically we can't actually iterate objects and instance during line art evaluation). I'm not that familiar with depsgraph to present a very solid solution for it, but there will be a solution to come. I actually want to revert back to the original object iterator since that's how line art has been doing stuff all this time, though it's incorrect and theoretically could cause access conflicts in depsgraph, we actually didn't have any(?) bug reports regarding line art crashes that's determined to be caused by this, and I myself haven't experienced this sort of crashes either (which is probably why I or GP guys never knew the way we are doing stuff is technically wrong).

Sergey Sharybin added

and removed

labels 2023-02-13 18:08:49 +01:00

Pratik Borhade referenced this issue

2023-12-11 05:59:26 +01:00

LineArt modifier does not work with geometry nodes instances #116018

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