Single bone unable to have weighting between 0 and 1, can only be 0 or 1 due to normalization #87714

New Issue

Mal Duffin · 2021-04-22T16:22:39+02:00

Mal Duffin commented

2021-04-22 16:22:39 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 465.89

Blender Version
Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: 02948a2cab
Worked: (newest version of Blender that worked as expected)

Short description of error
When weight painting, the weight doesn't always get used. Repeating the same action a few times is required, despite the visual representation of the weight map.

Exact steps for others to reproduce the error

Open a default scene
Add an armature
Parent the default box to use the armature, using envelope weights.
Paint the bottom of the box with zero ( blue ) weight, so that the bottom four vertices should not move.
Pose the armature, you'll notice that the vertices do move.
Repeat the painting a few times, and it will eventually work.

[Based on the default startup or an attached .blend file (as simple as possible)]

BlenderArmatureWeightPaint.mp4

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 465.89 **Blender Version** Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: `02948a2cab` Worked: (newest version of Blender that worked as expected) **Short description of error** When weight painting, the weight doesn't always get used. Repeating the same action a few times is required, despite the visual representation of the weight map. **Exact steps for others to reproduce the error** - Open a default scene - Add an armature - Parent the default box to use the armature, using envelope weights. - Paint the bottom of the box with zero ( blue ) weight, so that the bottom four vertices should not move. - Pose the armature, you'll notice that the vertices do move. - Repeat the painting a few times, and it will eventually work. [Based on the default startup or an attached .blend file (as simple as possible)] [BlenderArmatureWeightPaint.mp4](https://archive.blender.org/developer/F10032645/BlenderArmatureWeightPaint.mp4)

Mal Duffin commented

2021-04-22 16:22:39 +02:00

Added subscriber: @MalDuffin

Mal Duffin commented

2021-04-22 17:03:14 +02:00

Someone tested and confirmed that this works fine on Linux, so it could be a platform issue ( this happens on Windows, I had 6 other people have the same issue while doing some online training yesterday ).

Mal Duffin commented

2021-04-22 17:30:13 +02:00

WeightPaint_cube_rig-292-N01.zip

Try to move the armature, the whole cube moves. Check the weight paint on the cube, the bottom vertices are painted blue ( should have zero weight, and not move )

[WeightPaint_cube_rig-292-N01.zip](https://archive.blender.org/developer/F10032707/WeightPaint_cube_rig-292-N01.zip) Try to move the armature, the whole cube moves. Check the weight paint on the cube, the bottom vertices are painted blue ( should have zero weight, and not move )

Mal Duffin commented

2021-04-23 17:54:33 +02:00

On todays build of Blender 2.93 beta.

It seems that the vertex only stops moving when it is exactly 0. The other values ( eg 0.008 ) keep moving as if they were 1.

On todays build of Blender 2.93 beta. ![image.png](https://archive.blender.org/developer/F10034029/image.png) It seems that the vertex only stops moving when it is exactly 0. The other values ( eg 0.008 ) keep moving as if they were 1.

Nathan Vasil commented

2021-04-24 21:41:08 +02:00

Added subscriber: @vasiln

Nathan Vasil commented

2021-04-24 21:41:08 +02:00

Should probably be closed. Not a bug, just normalization of weights in the presence of a single bone. See conversation at https://blenderartists.org/t/is-weight-painting-broke-for-windows-set-of-steps-to-check/1300271 for more if you want.

Mal Duffin changed title from ~~Weight Painting Bug - Simple Example~~ to Single bone unable to have weighting between 0 and 1, can only be 0 or 1 due to normalization

2021-04-24 21:47:51 +02:00

Mal Duffin commented

2021-04-24 21:49:19 +02:00

Hi Nathan,

I changed the topic from...

Weight Painting Bug - Simple Example

to

Single bone unable to have weighting between 0 and 1, can only be 0 or 1 due to normalization

Now that the issue has been narrowed down, it is a bug.

In my case, I'd like to assign half-weights to some of the vertices controlled by a single bone, and am unable to.

Hi Nathan, I changed the topic from... - Weight Painting Bug - Simple Example to - Single bone unable to have weighting between 0 and 1, can only be 0 or 1 due to normalization Now that the issue has been narrowed down, it is a bug. In my case, I'd like to assign half-weights to some of the vertices controlled by a single bone, and am unable to.

Helge Grimhardt commented

2021-04-26 01:20:49 +02:00

Added subscriber: @Helge-4

Helge Grimhardt commented

2021-04-26 01:20:49 +02:00

I just checked out the above blenderartists.org thread. This issue might be something to think about for the usability folks around here...

However, if you just want to somehow make this work, you could set the bone's Vertex Group within the Armature Modifier's settings. This way you should be able to control the bone's influence on each vertex.

I just checked out the above blenderartists.org thread. This issue might be something to think about for the usability folks around here... However, if you just want to somehow make this work, you could set the bone's Vertex Group within the Armature Modifier's settings. This way you should be able to control the bone's influence on each vertex. ![grafik.png](https://archive.blender.org/developer/F10038131/grafik.png)

Mal Duffin commented

2021-04-26 07:38:10 +02:00

Hi Helge,

Many thanks for looking into it and for the suggestion, I’ll try it later on when I’m at the computer.

One code based solution might be to not normalise totals under 1. I get why they are normalised for totals over 1, although there are cases where the user might want this to occur.

If 3 bones have weight on the same vertex of eg 0.25, 0.5 and 0.75 these add up to 1.5 and currently get normalised. That’s fine, you can assume the artist would most likely want this, so that the total control over the vertex is 1. The bones would end up with the same relative influence over the vertex.

If the 3 bones are set by the artist to have weights of 0.1, 0.15 and 0.2 to have a small influence over a vertex, the total is 0.45. This is under 1, and should not be normalised.

In the same way, if an artist sets a single bone to have a weight of 0.1 over a vertex, this is under 1 and should not be normalised. They very likely want to have this small influence over the bone.

The above change would allow an artist subtle control with weight painting. Hope that makes sense!

Hi Helge, Many thanks for looking into it and for the suggestion, I’ll try it later on when I’m at the computer. One code based solution might be to not normalise totals under 1. I get why they are normalised for totals over 1, although there are cases where the user might want this to occur. If 3 bones have weight on the same vertex of eg 0.25, 0.5 and 0.75 these add up to 1.5 and currently get normalised. That’s fine, you can assume the artist would most likely want this, so that the total control over the vertex is 1. The bones would end up with the same relative influence over the vertex. If the 3 bones are set by the artist to have weights of 0.1, 0.15 and 0.2 to have a small influence over a vertex, the total is 0.45. This is under 1, and should not be normalised. In the same way, if an artist sets a single bone to have a weight of 0.1 over a vertex, this is under 1 and should not be normalised. They very likely want to have this small influence over the bone. The above change would allow an artist subtle control with weight painting. Hope that makes sense!

Omar Emara commented

2022-02-10 16:05:46 +01:00

Added subscriber: @OmarEmaraDev

Omar Emara commented

2022-02-10 16:05:46 +01:00

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

Omar Emara closed this issue

2022-02-10 16:05:46 +01:00

Omar Emara commented

2022-02-10 16:05:46 +01:00

Thanks for the report, but the issue reported here is a request for modified/improved behavior and not a bug in current behavior. Closing as this bug tracker is only for bugs and errors.

I can see you already suggested this on RCS: https://blender.community/c/rightclickselect/mrhbbc/?sorting=hot. So lets track that suggestion there instead.

For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug

Thanks for the report, but the issue reported here is a request for modified/improved behavior and not a bug in current behavior. Closing as this bug tracker is only for bugs and errors. I can see you already suggested this on RCS: https://blender.community/c/rightclickselect/mrhbbc/?sorting=hot. So lets track that suggestion there instead. For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug

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Single bone unable to have weighting between 0 and 1, can only be 0 or 1 due to normalization #87714