Grease pencil automatic weight is off #104077

New Issue

Gaku · 2023-01-23T02:51:19+01:00

Gaku commented

2023-01-23 02:51:19 +01:00

Hi
Automatic weights for GP seems off from geometry auto weight. I am assuming this should be same as geo so the drawing I did on surface should move together with geo?

cheers
Gaku

System Information
Windows 10

Blender Version
Blender 3.4

AUTOweight.blend).

Hi Automatic weights for GP seems off from geometry auto weight. I am assuming this should be same as geo so the drawing I did on surface should move together with geo? cheers Gaku **System Information** Windows 10 **Blender Version** Blender 3.4 ![image.png](https://archive.blender.org/developer/F14185655/image.png) [AUTOweight.blend](https://archive.blender.org/developer/F14185657/AUTOweight.blend)).

Gaku commented

2023-01-23 02:51:19 +01:00

Added subscriber: @GAKUTADA

Philipp Oeser commented

2023-01-23 10:07:47 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2023-01-23 10:07:47 +01:00

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

Philipp Oeser commented

2023-01-23 10:07:47 +01:00

Opposed to meshes, the distance plays a bigger role here it seems.
If I move the grease pencil points closer to the armature prior to parenting with automatic weights, it works properly.

Seems strange though, would assume the distances/weights to be approximately the same for greasepencil and meshes.
Will confirm for now

Opposed to meshes, the distance plays a bigger role here it seems. If I move the grease pencil points closer to the armature prior to parenting with automatic weights, it works properly. Seems strange though, would assume the distances/weights to be approximately the same for greasepencil and meshes. Will confirm for now

Philipp Oeser commented

2023-01-24 10:35:58 +01:00

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

Philipp Oeser commented

2023-01-24 10:35:58 +01:00

Added subscriber: @antoniov

Philipp Oeser commented

2023-01-24 10:35:58 +01:00

OK, so after a bit of digging, here are more findings:

the behavior of generating weights is dependent on a Ratio & Decay
when first parenting to the armature with Automatic Weights, these are not really exposed to the user (@antoniov : maybe this should show immediately? otherwise this does not seem very obvious... or at least elaborate on this in the manual )
you can however tweak this afterwards:
- with your file, select the Pencil object
- enter weightpaint mode
- Weights > Generate Weights > With Automatic Weights
- here you can tweak Ratio & Decay
  - increase Ratio a whole bunch (it goes up to 1.0 as soft limit, but you can type in 2.0 manually)

{F14192520 size=full}
This way, you can get better influence on the stroke:
{F14192526 size=full}

So in the (while not obvious for me either), this does not really look like a bug to me.
@GAKUTADA: does this work for you?

OK, so after a bit of digging, here are more findings: - the behavior of generating weights is dependent on a `Ratio` & `Decay` - when first parenting to the armature with Automatic Weights, these are not really exposed to the user (@antoniov : maybe this should show immediately? otherwise this does not seem very obvious... or at least elaborate on this in the [manual ](https://docs.blender.org/manual/en/3.5/grease_pencil/modifiers/deform/armature.html)) - you can however tweak this afterwards: - with your file, select the `Pencil` object - enter weightpaint mode - `Weights` > `Generate Weights` > `With Automatic Weights` - here you can tweak `Ratio` & `Decay` - increase `Ratio` a whole bunch (it goes up to 1.0 as soft limit, but you can type in 2.0 manually) {[F14192520](https://archive.blender.org/developer/F14192520/image.png) size=full} This way, you can get better influence on the stroke: {[F14192526](https://archive.blender.org/developer/F14192526/image.png) size=full} So in the (while not obvious for me either), this does not really look like a bug to me. @GAKUTADA: does this work for you?

Antonio Vazquez commented

2023-01-25 10:39:09 +01:00

@lichtwerk The parent operator is the same for Meshes or Grease Pencil, as you can see in the image below, and this operator never expose the Ratio and Decay.

Not sure if would be good to expose these values for this operator for any object type.

@lichtwerk The parent operator is the same for Meshes or Grease Pencil, as you can see in the image below, and this operator never expose the `Ratio` and `Decay`. ![image.png](https://archive.blender.org/developer/F14196333/image.png) Not sure if would be good to expose these values for this operator for any object type.

Philipp Oeser commented

2023-01-25 10:47:00 +01:00

In #104077#1479535, @antoniov wrote:
@lichtwerk The parent operator is the same for Meshes or Grease Pencil, as you can see in the image below, and this operator never expose the Ratio and Decay.
Not sure if would be good to expose these values for this operator for any object type.

I think it would be possible to conditionally use this only for greasepencil (and only show it in that case)

> In #104077#1479535, @antoniov wrote: > @lichtwerk The parent operator is the same for Meshes or Grease Pencil, as you can see in the image below, and this operator never expose the `Ratio` and `Decay`. > Not sure if would be good to expose these values for this operator for any object type. I think it would be possible to conditionally use this only for greasepencil (and only show it in that case)

Antonio Vazquez commented

2023-01-25 10:51:45 +01:00

Sure, we can define a UI callback...let me check.

Antonio Vazquez self-assigned this 2023-01-25 10:54:37 +01:00

Antonio Vazquez commented

2023-01-25 11:11:08 +01:00

@lichtwerk These values are not defined as parameters in OBJECT_OT_parent_set. Looking at the code, it needs to pass the values to different functions that actually are not using it to finally pass to ED_gpencil_add_armature_weights I'm not sure add these parameters is good idea...there are a lot of places that are using ED_object_parent_set that calls gpencil parent weight function.

@lichtwerk These values are not defined as parameters in `OBJECT_OT_parent_set`. Looking at the code, it needs to pass the values to different functions that actually are not using it to finally pass to `ED_gpencil_add_armature_weights` I'm not sure add these parameters is good idea...there are a lot of places that are using `ED_object_parent_set` that calls gpencil parent weight function.

Gaku commented

2023-01-26 00:04:11 +01:00

Changing weight tweak ratio helps!
I was expecting this (ratio 2) should be default as it seems same as geo's behavior but really good to know I can fix by this. thanks!

Changing weight tweak ratio helps! I was expecting this (ratio 2) should be default as it seems same as geo's behavior but really good to know I can fix by this. thanks!

Philipp Oeser commented

2023-01-26 10:00:27 +01:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2023-01-26 10:00:27 +01:00

Added subscriber: @Blendify

Philipp Oeser commented

2023-01-26 10:00:27 +01:00

In #104077#1479571, @antoniov wrote:
I'm not sure add these parameters is good idea...there are a lot of places ...

Understood. To prevent future confusion, maybe this should be mentioned in the to the documentation though?
https://docs.blender.org/manual/en/3.5/animation/armatures/skinning/parenting.html#with-automatic-weights
https://docs.blender.org/manual/en/3.5/grease_pencil/modifiers/deform/armature.html

CC @Blendify

> In #104077#1479571, @antoniov wrote: > I'm not sure add these parameters is good idea...there are a lot of places ... Understood. To prevent future confusion, maybe this should be mentioned in the to the documentation though? https://docs.blender.org/manual/en/3.5/animation/armatures/skinning/parenting.html#with-automatic-weights https://docs.blender.org/manual/en/3.5/grease_pencil/modifiers/deform/armature.html CC @Blendify

Antonio Vazquez removed their assignment 2023-01-27 19:25:59 +01:00

Philipp Oeser removed the

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Grease pencil automatic weight is off #104077