Weight Paint Mode Mirror Vertex Groups not working #116115

New Issue

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2023-12-14 18:30:08 +01:00

labels 2023-12-13 05:45:22 +01:00

Leon commented

I tried it out in 4.1 now and the problems still persist. I took a few screenshots to hopefully better illustrate the problems.
(The "active side" is the bone I weight painted on and the "passive side" is the mirrored bone.)

I tried it out in 4.1 now and the problems still persist. I took a few screenshots to hopefully better illustrate the problems. (The "active side" is the bone I weight painted on and the "passive side" is the mirrored bone.) ![Blender Weight Paint Symmetry Bug_1.jpg](/attachments/1c3afb7f-40a0-4058-b154-78bf713a9f36) ![Blender Weight Paint Symmetry Bug_2.jpg](/attachments/c3d7938c-2e0e-407c-b113-123843f4090b) ![Blender Weight Paint Symmetry Bug_3.jpg](/attachments/50998a06-cd1e-4277-8b23-9f821407e6d5) ![Blender Weight Paint Symmetry Bug_4.jpg](/attachments/2b40e540-07cc-45bf-90b5-f2c94a1b5af2) ![Blender Weight Paint Symmetry Bug_5.jpg](/attachments/8effd065-5a90-4ba0-9eeb-ebf21c3c4b23)

Blender Weight Paint Symmetry Bug_2.jpg

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Blender Weight Paint Symmetry Bug_4.jpg

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Blender Weight Paint Symmetry Bug_1.jpg

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Blender Weight Paint Symmetry Bug_3.jpg

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Blender Weight Paint Symmetry Bug_5.jpg

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Pratik Borhade commented

2023-12-15 05:56:15 +01:00

Thanks. Can you share .blend file to be able to verify the issue locally.

Leon commented

2023-12-15 11:16:19 +01:00

Yes of course. Here's the file I set up for the tests. Though it's in the state before anything was weightpainted, so you can properly try out all the different modes.
Weightpaint Symmetry Test 4.1.blend

Yes of course. Here's the file I set up for the tests. Though it's in the state before anything was weightpainted, so you can properly try out all the different modes. [Weightpaint Symmetry Test 4.1.blend](/attachments/519655a6-feb8-4da0-a8b6-90548b095d71)

Weightpaint Symmetry Test 4.1.blend

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Pratik Borhade added

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2024-01-02 14:13:26 +01:00

labels 2024-01-02 10:48:07 +01:00

Philipp Oeser commented

I think the primary description of the issue does not really correspond to the screenshots provided?

The primary description mentions:

symmetric mesh and top
"If "Topology Mirror" is inactive, the Mirror Vertex Group option does not work at all

Cannot repro this, also the screenshots for this case (the leftmost column) indicates all combinations are "Behavior expected"

The report description also does not mention for which scenario/combination the behavior changed between 3.6 and 4.0.

Could we try again to clarify this? Thx in advance

I think the primary description of the issue does not really correspond to the screenshots provided? The primary description mentions: - symmetric mesh and top - "If "Topology Mirror" is inactive, the Mirror Vertex Group option does not work at all Cannot repro this, also the screenshots for this case (the leftmost column) indicates all combinations are "Behavior expected" The report description also does not mention for which scenario/combination the behavior changed between 3.6 and 4.0. Could we try again to clarify this? Thx in advance

Philipp Oeser added

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2024-01-02 15:32:26 +01:00

labels 2024-01-02 14:13:38 +01:00

Leon commented

Hi there @lichtwerk , I'm not sure I understand what exactly is unclear to you, but I hope the following helps.

Is it possible that the last two screenshots are a bit confusing here? Because in these the "X-Mirror" Option is disabled in the first place therefore I didn't find it unexpected that nothing is getting mirrored. I added them for completions sake, to have all possible combinations covered, but for all intents and purposes regarding the initial problem/s the last two screenshots can probably be ignored.

The 2nd and 3rd screenshots are the one corresponding to the described problem, namely that:

Mirror Vertex Groups + Mirror: X should lead to the weight painting being mirrored in the same way mirroring works in sculpt mode
Mirror Vertex Groups + Mirror: X + Topology Mirror should work for asymmetrical Meshes with mirrored Topology (and additionally should definitely not lead to the result in the middle column of the 3rd screenshot)

I hope this helps a bit with the clarification, otherwise please let me know 🙂
Best regards and happy new year 🥳

Hi there @lichtwerk , I'm not sure I understand what exactly is unclear to you, but I hope the following helps. Is it possible that the last two screenshots are a bit confusing here? Because in these the "X-Mirror" Option is disabled in the first place therefore I didn't find it unexpected that nothing is getting mirrored. I added them for completions sake, to have all possible combinations covered, but for all intents and purposes regarding the initial problem/s the last two screenshots can probably be ignored. The 2nd and 3rd screenshots are the one corresponding to the described problem, namely that: 1. Mirror Vertex Groups + Mirror: X should lead to the weight painting being mirrored in the same way mirroring works in sculpt mode 2. Mirror Vertex Groups + Mirror: X + Topology Mirror should work for asymmetrical Meshes with mirrored Topology (and additionally should definitely not lead to the result in the middle column of the 3rd screenshot) I hope this helps a bit with the clarification, otherwise please let me know 🙂 Best regards and happy new year 🥳

Philipp Oeser added

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2024-01-18 11:51:23 +01:00

labels 2024-01-18 11:45:18 +01:00

Philipp Oeser commented

Mirror Vertex Groups + Mirror: X should lead to the weight painting being mirrored in the same way mirroring works in sculpt mode

Second screenshot indicates that this is working for you (except for the Asymmetric Mesh (symmetric Topo) case). But since Topology Mirror is OFF, why should that case work?

Mirror Vertex Groups + Mirror: X + Topology Mirror should work for asymmetrical Meshes with mirrored Topology (and additionally should definitely not lead to the result in the middle column of the 3rd screenshot)

That case I need to check again

The report description also does not mention for which scenario/combination the behavior changed between 3.6 and 4.0.

This is not answered yet

>1. Mirror Vertex Groups + Mirror: X should lead to the weight painting being mirrored in the same way mirroring works in sculpt mode Second screenshot indicates that this is working for you (except for the `Asymmetric Mesh (symmetric Topo)` case). But since Topology Mirror is OFF, why should that case work? >2. Mirror Vertex Groups + Mirror: X + Topology Mirror should work for asymmetrical Meshes with mirrored Topology (and additionally should definitely not lead to the result in the middle column of the 3rd screenshot) That case I need to check again >The report description also does not mention for which scenario/combination the behavior changed between 3.6 and 4.0. This is not answered yet

Leon commented

2024-01-18 19:17:11 +01:00

Second screenshot indicates that this is working for you (except for the Asymmetric Mesh (symmetric Topo) case). But since Topology Mirror is OFF, why should that case work?

The Mesh "Asymmetric Mesh (symmetric Topology) is just very slightly asymmetric. Therefore I'd expect Vertices on the mirrored side which are in the Radius of the Weightpaint Brush to be influenced accordingly.
At least this is what would happen in Sculpt Mode. Here's a quick example of the same Mesh, but with the one arm moved to the side and instead a sphere in the location and roughly with the diameter of the arm/wrist at that point. See the dot(s) of the brush on the mirrored Vertices:

Does that make a little more sense? Maybe it's the Sculpt Mode that is confusing me here, but to me the way Sculpt works in this case seems to make sense and therefore I'd expect other Modes to work the same way.

This is not answered yet

I'm not sure what it was anymore, sorry. Just tested it and it seems to have the same problems as 4.0

> Second screenshot indicates that this is working for you (except for the `Asymmetric Mesh (symmetric Topo)` case). But since Topology Mirror is OFF, why should that case work? The Mesh "Asymmetric Mesh (symmetric Topology) is just very slightly asymmetric. Therefore I'd expect Vertices on the mirrored side which are in the Radius of the Weightpaint Brush to be influenced accordingly. At least this is what would happen in Sculpt Mode. Here's a quick example of the same Mesh, but with the one arm moved to the side and instead a sphere in the location and roughly with the diameter of the arm/wrist at that point. See the dot(s) of the brush on the mirrored Vertices: ![image](/attachments/54755caa-e11f-4642-ab1c-2fb8542faba8) Does that make a little more sense? Maybe it's the Sculpt Mode that is confusing me here, but to me the way Sculpt works in this case seems to make sense and therefore I'd expect other Modes to work the same way. > This is not answered yet I'm not sure what it was anymore, sorry. Just tested it and it seems to have the same problems as 4.0

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Philipp Oeser commented

2024-01-19 11:38:13 +01:00

I'm not sure what it was anymore, sorry. Just tested it and it seems to have the same problems as 4.0

I will remove this from the report description then

Worked: (3.6.5 though not quite as expected either)

> I'm not sure what it was anymore, sorry. Just tested it and it seems to have the same problems as 4.0 I will remove this from the report description then >Worked: (3.6.5 though not quite as expected either)

👍 1

Philipp Oeser commented

2024-03-21 13:48:00 +01:00

Sorry again this took a while to answer.

The Mesh "Asymmetric Mesh (symmetric Topology) is just very slightly asymmetric. Therefore I'd expect Vertices on the mirrored side which are in the Radius of the Weightpaint Brush to be influenced accordingly. At least this is what would happen in Sculpt Mode

This is indeed different in weightpaint mode (with Mirror Vertex Groups ON) vs. sculptmode -- or vs. weightpaint mode (with Mirror Vertex Groups OFF). In weightpaint (with Mirror Vertex Groups ON), there are no symmetry strokes on "the other side" :

/* We don't do any symmetry strokes when mirroring vertex groups. */

So with Mirror Vertex Groups OFF, you will actually get the behavior you described from sculptmode : the brush location gets mirrored and everything inside the brush radius (based off of the mirrored location) is still affected

With Mirror Vertex Groups ON, we dont have mirrored strokes, instead the weights get copied over and this then depends on mesh_get_x_mirror_vert to determine which verts to copy the weight to. Using a KDTree and the following threshold

#define KD_THRESH 0.00002f

This might be unexpected, but does this at least explain the situation from the code side of view?

From the user side of view, I do understand that this is a bit unintuitive.
It might even be possible to not use the KDTree and just use mirrored strokes, but this is probably a little more involved (also some research would have to be done prior to actually know why the current approach was chosen). Will also ask around in chat.

Regarding the whole Topology Mirror side of things: I cannot properly comment on that, see also discussion in #81698

Sorry again this took a while to answer. >The Mesh "Asymmetric Mesh (symmetric Topology) is just very slightly asymmetric. Therefore I'd expect Vertices on the mirrored side which are in the Radius of the Weightpaint Brush to be influenced accordingly. At least this is what would happen in Sculpt Mode This is indeed different in weightpaint mode (with `Mirror Vertex Groups` ON) vs. sculptmode -- or vs. weightpaint mode (with `Mirror Vertex Groups` OFF). In weightpaint (with `Mirror Vertex Groups` ON), there are no symmetry **strokes** on "the other side" : `/* We don't do any symmetry strokes when mirroring vertex groups. */` So with `Mirror Vertex Groups` OFF, you will actually get the behavior you described from sculptmode : the brush location gets mirrored and everything inside the brush radius (based off of the mirrored location) is still affected With `Mirror Vertex Groups` ON, we dont have mirrored strokes, instead the weights get copied over and this then depends on `mesh_get_x_mirror_vert` to determine which verts to copy the weight to. Using a KDTree and the following threshold `#define KD_THRESH 0.00002f` This might be unexpected, but does this at least explain the situation from the code side of view? From the user side of view, I do understand that this is a bit unintuitive. It might even be possible to not use the KDTree and just use mirrored strokes, but this is probably a little more involved (also some research would have to be done prior to actually know why the current approach was chosen). Will also ask around in chat. Regarding the whole Topology Mirror side of things: I cannot properly comment on that, see also discussion in #81698

Philipp Oeser commented

2024-03-21 14:30:20 +01:00

but does this at least explain the situation from the code side of view?

@PanicPug : ^^

> but does this at least explain the situation from the code side of view? @PanicPug : ^^

Philipp Oeser added

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2024-04-04 09:47:44 +02:00

labels 2024-03-21 14:30:32 +01:00

Philipp Oeser commented

poke ^^

Leon commented

2024-04-04 18:00:48 +02:00

Hi, sorry for the late reply on my part this time. Thank you for the research and explanations. I don't fully understand the technicalities behind it, but I think I get the gist of it.
As you said, from a user perspective it's somewhat unintuitive, so if it would be possible to use mirrored strokes, it might be a great help for Weightpainting. If you manage to find out more about it and maybe get an answer from the chat, I'd be very interested :)

The discussion you linked (#81698), I can unfortunately not see, only getting a 404 Error when I click on it.

Thanks again for all your work on this.

Hi, sorry for the late reply on my part this time. Thank you for the research and explanations. I don't fully understand the technicalities behind it, but I think I get the gist of it. As you said, from a user perspective it's somewhat unintuitive, so if it would be possible to use mirrored strokes, it might be a great help for Weightpainting. If you manage to find out more about it and maybe get an answer from the chat, I'd be very interested :) The discussion you linked (#81698), I can unfortunately not see, only getting a 404 Error when I click on it. Thanks again for all your work on this.

Philipp Oeser added

and removed