Weight painting on Grease Pencil object with falloff problems #62303

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Thomas Kress · 2019-03-07T11:19:07+01:00

Thomas Kress commented

2019-03-07 11:19:07 +01:00

System Information
Operating system: OSX 10.14.3
Graphics card: NVIDIA GeForce GTX 780M

Blender Version
Broken: 2.80 Date: 2019-03-06 23:12 Hash:a070815d127e
Worked: (optional)

Short description of error
Strange falloff behaviour with weight painting on Grease Pencil objects with mouse and tablet

Exact steps for others to reproduce the error

create grease pencil object
switch to Weight Paint mode
select weight tool
falloff seems to work with all radius and strength settings
changing the weight value to 0
falloff doesn't work anymore

additional quirk:

the strength value has to be really low to work properly with falloffs -> under 0.1

**System Information** Operating system: OSX 10.14.3 Graphics card: NVIDIA GeForce GTX 780M **Blender Version** Broken: 2.80 Date: 2019-03-06 23:12 Hash:a070815d127e Worked: (optional) **Short description of error** Strange falloff behaviour with weight painting on Grease Pencil objects with mouse and tablet **Exact steps for others to reproduce the error** - create grease pencil object - switch to Weight Paint mode - select weight tool - falloff seems to work with all radius and strength settings - changing the weight value to 0 - falloff doesn't work anymore additional quirk: - the strength value has to be really low to work properly with falloffs -> under 0.1

Thomas Kress commented

2019-03-07 11:19:07 +01:00

Added subscriber: @tkress

Antonio Vazquez was assigned by Sebastian Parborg

2019-03-07 11:55:38 +01:00

Antonio Vazquez commented

2019-03-07 17:59:48 +01:00

Not sure if you are talking of this "weight" parameter.

But, if you set this value to 0, then you cannot paint, because this is the target weight, that means that you are trying to paint a weight of zero, and this does nothing.

Maybe, I understood wrongly your problem.

Not sure if you are talking of this "weight" parameter. ![image.png](https://archive.blender.org/developer/F6780106/image.png) But, if you set this value to 0, then you cannot paint, because this is the target weight, that means that you are trying to paint a weight of zero, and this does nothing. Maybe, I understood wrongly your problem.

Thomas Kress commented

2019-03-08 09:30:18 +01:00

The weight painting falloff should be similar in both directions. A weight value of 0 should falloff towards red and a weight value of 1 should falloff towards blue.

The weight painting falloff should be similar in both directions. A weight value of 0 should falloff towards red and a weight value of 1 should falloff towards blue. ![falloff.jpg](https://archive.blender.org/developer/F6783502/falloff.jpg)

Antonio Vazquez commented

2019-03-08 10:55:09 +01:00

I see what you mean now... I will take a look.

Antonio Vazquez commented

2019-03-08 11:13:49 +01:00

@tkress Looking at the code and how it's designed this cannot be consider a bug and I explain why.

The weight parameter is the maximum value you can use for the weight, if you set to 0.5, the maximum value will be that. If you set to 0, means, you want a maximum value of 0.

In order to do what you want, it's very simple. Set the target value to 1 (to allow values greater than 0) and simply press CTRL key while you are drawing to "subtract" weights. You will see that weights are using the falloff because you have a maximum value with "something" and subtract weights with the painting process. Of course you could set weight to 0.5 and falloff from 0.5 to 0.

I think all this is related to a misunderstanding of what the weight parameter means... maybe we need clarify tooltip.

@tkress Looking at the code and how it's designed this cannot be consider a bug and I explain why. The weight parameter is the maximum value you can use for the weight, if you set to 0.5, the maximum value will be that. If you set to 0, means, you want a maximum value of 0. In order to do what you want, it's very simple. Set the target value to 1 (to allow values greater than 0) and simply press **CTRL** key while you are drawing to "subtract" weights. You will see that weights are using the falloff because you have a maximum value with "something" and subtract weights with the painting process. Of course you could set weight to 0.5 and falloff from 0.5 to 0. I think all this is related to a misunderstanding of what the weight parameter means... maybe we need clarify tooltip.

Antonio Vazquez commented

2019-03-08 11:22:16 +01:00

Added subscriber: @WilliamReynish

Antonio Vazquez commented

2019-03-08 11:22:16 +01:00

@WilliamReynish Could you review the tooltip of this parameter in rna_sculpt_paint.c parameter "weight" (line 1423)?

Maybe, we could include a better descriptive text of what is doing this parameter.

Maybe, something like "Maximum weight value allowed as target. Any value above will be clamped"

@WilliamReynish Could you review the tooltip of this parameter in *rna_sculpt_paint.c* parameter *"weight"* (line 1423)? Maybe, we could include a better descriptive text of what is doing this parameter. Maybe, something like *"Maximum weight value allowed as target. Any value above will be clamped"*

Thomas Kress commented

2019-03-08 11:30:59 +01:00

I see.
I think the first thought is - i am in a kind of visual painting mode environment and i am dealing with some colors from blue to red - i am using a brush tool and expect the behaviour of usual painting processes.

Thanks

I see. I think the first thought is - i am in a kind of visual painting mode environment and i am dealing with some colors from blue to red - i am using a brush tool and expect the behaviour of usual painting processes. Thanks

Antonio Vazquez commented

2019-03-08 11:41:43 +01:00

Changed status from 'Open' to: 'Archived'

Antonio Vazquez closed this issue

2019-03-08 11:41:43 +01:00

Antonio Vazquez commented

2019-03-08 11:41:43 +01:00

Yes, but weight paint is not a "real" paint... it's an add/substract value process.

We can close the task report and reopen it if we need it in the future.

Yes, but weight paint is not a "real" paint... it's an add/substract value process. We can close the task report and reopen it if we need it in the future.

Dave F commented

2023-01-08 12:42:58 +01:00

Added subscriber: @df-1

Dave F commented

2023-01-08 12:42:58 +01:00

I'm also very confused by the falloff behaviour of grease pencil weight painting. In this video you can see I set the falloff to constant, try to paint (expecting everything within the brush circle to simply get set to the specified value) and it appears to have a soft falloff. grease pencil weight paint falloff 2023-01-08 11-37-21.mp4

I did wonder if it was related to this https://developer.blender.org/T65408 but the problem seems to occur both with painting weight value 1 and painting weight value 0, so perhaps it's not that. It feels like a bug but maybe I just don't understand it?

System info System Information
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.40

Blender Version
Broken: version: 3.4.1, branch: blender-v3.4-release, commit date: 2022-12-19 17:00, hash: 55485cb379

I'm also very confused by the falloff behaviour of grease pencil weight painting. In this video you can see I set the falloff to constant, try to paint (expecting everything within the brush circle to simply get set to the specified value) and it appears to have a soft falloff. [grease pencil weight paint falloff 2023-01-08 11-37-21.mp4](https://archive.blender.org/developer/F14133135/grease_pencil_weight_paint_falloff_2023-01-08_11-37-21.mp4) I did wonder if it was related to this https://developer.blender.org/T65408 but the problem seems to occur both with painting weight value 1 and painting weight value 0, so perhaps it's not that. It feels like a bug but maybe I just don't understand it? System info **System Information** Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.40 **Blender Version** Broken: version: 3.4.1, branch: blender-v3.4-release, commit date: 2022-12-19 17:00, hash: `55485cb379`

Dave F commented

2023-01-08 13:01:54 +01:00

Just been testing further and I'm very confused by this! So, this is a straight line, weighted to a single bone that moves it vertically. I painted the left one with smooth falloff and the right one with constant falloff. I'd been assuming that the color coding would be directly proportional to the amount of displacement you'd get from the bone, and that the shape of the displacement would match the icon of the falloff mode, but as you can see that is absolutely not the case.

As an additional tests, here's the same line weighted to 3 bones, the first with a weight of 0, the second with smooth vs constant falloff, and the third with a weight of 1. Only the second bone is moved.

This is not at all what I was expecting (shapes that match the brush icons), but I don't know enough to be able to say if this is a bug or not?

![image.png](https://archive.blender.org/developer/F14133159/image.png) ![image.png](https://archive.blender.org/developer/F14133173/image.png) Just been testing further and I'm very confused by this! So, this is a straight line, weighted to a single bone that moves it vertically. I painted the left one with smooth falloff and the right one with constant falloff. I'd been assuming that the color coding would be directly proportional to the amount of displacement you'd get from the bone, and that the shape of the displacement would match the icon of the falloff mode, but as you can see that is absolutely not the case. As an additional tests, here's the same line weighted to 3 bones, the first with a weight of 0, the second with smooth vs constant falloff, and the third with a weight of 1. Only the second bone is moved. ![image.png](https://archive.blender.org/developer/F14133176/image.png) This is not at all what I was expecting (shapes that match the brush icons), but I don't know enough to be able to say if this is a bug or not?

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Weight painting on Grease Pencil object with falloff problems #62303