Rotate sculpting brush may have an incorrect pen pressure behavior #83697

New Issue

s12a · 2020-12-12T12:29:13+01:00

s12a commented

2020-12-12 12:29:13 +01:00

System Information
Operating system: Linux-5.9.12-1-default-x86_64-with-glibc2.17 64 Bits
Graphics card: AMD Radeon (TM) RX 480 Graphics (POLARIS10, DRM 3.39.0, 5.9.12-1-default, LLVM 11.0.0) X.Org 4.6 (Core Profile) Mesa 20.2.4

Blender Version
Broken: version: 2.92.0 Alpha, branch: master, commit date: 2020-12-11 22:08, hash: 0c1d476923
Worked: (newest version of Blender that worked as expected)

Short description of error
The sensitivity to pressure of the Rotate Brush in Sculpting mode appears to be too low: no matter how hard the pen is pressed on the pen tablet, disabling pressure sensitivity produces much more controllable/faster results. Potentially other brushes in sculpting mode could be affected as well in various ways (only a general impression; unclear as of yet).

With Grease Pencil, pen pressure sensitivity appears to be correct and similar to that observed with a typical drawing program (Krita). So, this does not seem to be a general problem with Blender or my own pen tablet.

My pen tablet is a Wacom Intuos 5 Large. In Tablet settings inside Blender Preferences > Input, Max Threshold = 1.0 (max), Softness = 0.0

Exact steps for others to reproduce the error

Open the attached .blend file
Use the Rotate sculpting brush to attempt rotating the bumps on the provided plane object
Enable Pressure sensitivity for "Strength" in the brush and attempt it again applying maximum pressure on the pen tablet. Compare the difference in response

rotatebrush-veryhard.blend

**System Information** Operating system: Linux-5.9.12-1-default-x86_64-with-glibc2.17 64 Bits Graphics card: AMD Radeon (TM) RX 480 Graphics (POLARIS10, DRM 3.39.0, 5.9.12-1-default, LLVM 11.0.0) X.Org 4.6 (Core Profile) Mesa 20.2.4 **Blender Version** Broken: version: 2.92.0 Alpha, branch: master, commit date: 2020-12-11 22:08, hash: `0c1d476923` Worked: (newest version of Blender that worked as expected) **Short description of error** The sensitivity to pressure of the Rotate Brush in Sculpting mode appears to be too low: no matter how hard the pen is pressed on the pen tablet, disabling pressure sensitivity produces much more controllable/faster results. Potentially other brushes in sculpting mode could be affected as well in various ways (only a general impression; unclear as of yet). With Grease Pencil, pen pressure sensitivity appears to be correct and similar to that observed with a typical drawing program (Krita). So, this does not seem to be a general problem with Blender or my own pen tablet. My pen tablet is a Wacom Intuos 5 Large. In Tablet settings inside Blender Preferences > Input, Max Threshold = 1.0 (max), Softness = 0.0 **Exact steps for others to reproduce the error** - Open the attached .blend file - Use the Rotate sculpting brush to attempt rotating the bumps on the provided plane object - Enable Pressure sensitivity for "Strength" in the brush and attempt it again applying maximum pressure on the pen tablet. Compare the difference in response [rotatebrush-veryhard.blend](https://archive.blender.org/developer/F9504461/rotatebrush-veryhard.blend)

s12a commented

2020-12-12 12:29:13 +01:00

Added subscriber: @s12a

Pratik Borhade commented

2021-06-25 11:44:23 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-06-25 11:44:23 +02:00

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

Pratik Borhade commented

2021-06-25 11:44:23 +02:00

@s12a , can you please confirm the problem with 2.93LTS?

Don't know who uses tablet with Linux OS. May be Falk David can confirm if problem is still there for you ?

@s12a , can you please confirm the problem with 2.93LTS? Don't know who uses tablet with Linux OS. May be Falk David can confirm if problem is still there for you ?

s12a commented

2021-06-25 12:00:08 +02:00

This comment was removed by @s12a

*This comment was removed by @s12a*

Pratik Borhade commented

2021-06-25 12:04:42 +02:00

Added subscriber: @filedescriptor

Pratik Borhade commented

2021-06-25 12:04:42 +02:00

Thanks for checking. I don't have such system to test right now.

@filedescriptor can you try to replicate this?

Thanks for checking. I don't have such system to test right now. @filedescriptor can you try to replicate this?

s12a commented

2021-06-25 12:10:24 +02:00

(the deleted message was due to me confusing this with a different bug I recently reported)

@PratikPB2123
I just tested this bug with 2.93.1 LTS on Windows x64 and I can reproduce it again. The Rotate sculpting brush appears to rotate the bumps on the provided surface in the initially provided .blend file much faster without pen pressure on Strength enabled than with, even after confirming in the Wacom Control Panel that the applied pen pressure was indeed maximum.

3.0 alpha 3d7021b4ec also behaves the same.

EDIT: to clarify, when I initially reported the bug months ago I was using Linux, but at the moment I'm using Windows and it can be still reproduced. So it also seems to be OS-independent.

*(the deleted message was due to me confusing this with a different bug I recently reported)* @PratikPB2123 I just tested this bug with 2.93.1 LTS on Windows x64 and I can reproduce it again. The Rotate sculpting brush appears to rotate the bumps on the provided surface in the initially provided .blend file much faster *without* pen pressure on Strength enabled than with, even after confirming in the Wacom Control Panel that the applied pen pressure was indeed maximum. 3.0 alpha 3d7021b4ec23 also behaves the same. EDIT: to clarify, when I initially reported the bug months ago I was using Linux, but at the moment I'm using Windows and it can be still reproduced. So it also seems to be OS-independent.

s12a commented

2021-06-25 13:00:18 +02:00

As an additional note following more testing:

Using constant brush falloff without pen pressure on Strength, the behavior of the Rotate brush is very consistent and operates exactly as expected, with 1:1 mapping between the rotating motion of the cursor and geometry.

When Strength is enabled, again with constant brush falloff, things start getting weird. Not only the underlying geometry appears to rotate at least 2 times slower, but this value also changes depending on the starting pen pressure when the sculpting stroke was first initiated.

In other words, if the rotating sculpting motion is initiated with a low pressure, then no matter how hard the pen will be pressed afterwards, the rotation will remain very slow. Likewise, if the sculpting motion is initiated with a strong pen pressure, brush response will remain elevated during the entire brush stroke (but still lower than without Pen pressure/Strength enabled).

As an additional note following more testing: Using *constant* brush falloff without pen pressure on Strength, the behavior of the Rotate brush is very consistent and operates exactly as expected, with 1:1 mapping between the rotating motion of the cursor and geometry. When Strength is enabled, again with constant brush falloff, things start getting weird. Not only the underlying geometry appears to rotate at least 2 times slower, but this value also changes depending on the starting pen pressure when the sculpting stroke was first initiated. In other words, if the rotating sculpting motion is initiated with a low pressure, then no matter how hard the pen will be pressed afterwards, the rotation will remain very slow. Likewise, if the sculpting motion is initiated with a strong pen pressure, brush response will remain elevated during the entire brush stroke (but still lower than without Pen pressure/Strength enabled).

Richard Antalik commented

2021-07-06 04:38:41 +02:00

Added subscribers: @PrototypeNM1, @iss

Richard Antalik commented

2021-07-06 04:38:41 +02:00

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

Richard Antalik commented

2021-07-06 04:38:41 +02:00

In #83697#1182573, @s12a wrote:
I just tested this bug with 2.93.1 LTS on Windows x64 and I can reproduce it again. The Rotate sculpting brush appears to rotate the bumps on the provided surface in the initially provided .blend file much faster without pen pressure on Strength enabled than with, even after confirming in the Wacom Control Panel that the applied pen pressure was indeed maximum.

3.0 alpha 3d7021b4ec also behaves the same.

EDIT: to clarify, when I initially reported the bug months ago I was using Linux, but at the moment I'm using Windows and it can be still reproduced. So it also seems to be OS-independent.

@PrototypeNM1 Can you check this?

> In #83697#1182573, @s12a wrote: > I just tested this bug with 2.93.1 LTS on Windows x64 and I can reproduce it again. The Rotate sculpting brush appears to rotate the bumps on the provided surface in the initially provided .blend file much faster *without* pen pressure on Strength enabled than with, even after confirming in the Wacom Control Panel that the applied pen pressure was indeed maximum. > > 3.0 alpha 3d7021b4ec23 also behaves the same. > > > EDIT: to clarify, when I initially reported the bug months ago I was using Linux, but at the moment I'm using Windows and it can be still reproduced. So it also seems to be OS-independent. @PrototypeNM1 Can you check this?

Nicholas Rishel commented

2021-07-06 04:52:08 +02:00

@iss OS independent and existing in 2.93 indicates to me this is either in GP or the hardware itself. At a glance this doesn't look like my area.

Richard Antalik commented

2021-07-06 05:42:05 +02:00

In #83697#1187349, @PrototypeNM1 wrote:
@iss OS independent and existing in 2.93 indicates to me this is either in GP or the hardware itself. At a glance this doesn't look like my area.

The quote indicates, that this isn't OS specific, that's why I asked you. I can't check behavior here though so don't know which module this task would belong to.

> In #83697#1187349, @PrototypeNM1 wrote: > @iss OS independent and existing in 2.93 indicates to me this is either in GP or the hardware itself. At a glance this doesn't look like my area. The quote indicates, that this isn't OS specific, that's why I asked you. I can't check behavior here though so don't know which module this task would belong to.

Nicholas Rishel commented

2021-07-06 20:13:41 +02:00

Follow up to our discussion in chat: we clarified that the issue is OS independent.

To me this looks like an issue with the brush itself, which would be Sculpt, Paint & Texture module (I've gone ahead and added it). @s12a it might help clarify the issue if you could upload a video comparing what's expected vs what's happening.

Follow up to our discussion in chat: we clarified that the issue is OS independent. To me this looks like an issue with the brush itself, which would be Sculpt, Paint & Texture module (I've gone ahead and added it). @s12a it might help clarify the issue if you could upload a video comparing what's expected vs what's happening.

s12a commented

2021-07-06 20:57:35 +02:00

Here is a demonstration of the issue, using Blender 2.93 LTS with factory settings. For further clarity, the brush falloff was set to "Constant".

20210706-rotate-brush-bug-demonstration.mp4

Here is a demonstration of the issue, using Blender 2.93 LTS with factory settings. For further clarity, the brush falloff was set to "Constant". [20210706-rotate-brush-bug-demonstration.mp4](https://archive.blender.org/developer/F10214747/20210706-rotate-brush-bug-demonstration.mp4)

Philipp Oeser commented

2021-09-20 14:37:36 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-09-20 14:37:36 +02:00

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

Philipp Oeser commented

2021-09-20 14:37:36 +02:00

Can confirm.

This is because pressure is only taken once at the very beginning of the stroke if the stroke does not support changing radius while dragging (see paint_supports_dynamic_size, sculpt_update_cache_variants, sculpt_is_grab_tool)
A similar thing came up for radius (but was closed, see studio/blender-studio#56930 (Brush size pressure setting broken)), but I think here (for pressure) it could actually make sense to support sensitivity.
Especially because you will never be able to get 1.0 strength when starting a stroke.

Got a patch for this (not sure if this is desired in all situations)

Can confirm. This is because pressure is only taken once at the very beginning of the stroke if the stroke does not support changing radius while dragging (see `paint_supports_dynamic_size`, `sculpt_update_cache_variants`, `sculpt_is_grab_tool`) A similar thing came up for radius (but was closed, see studio/blender-studio#56930 (Brush size pressure setting broken)), but I think here (for pressure) it could actually make sense to support sensitivity. Especially because you will never be able to get 1.0 strength when starting a stroke. Got a patch for this (not sure if this is desired in all situations)

Nicholas Rishel commented

2021-09-20 18:51:03 +02:00

Removed subscriber: @PrototypeNM1

Julien Kaspar commented

2022-05-19 11:29:24 +02:00

Added subscriber: @JulienKaspar

Julien Kaspar commented

2022-05-19 11:29:24 +02:00

I tested D12568 and it doesn't fix the issue. We should disable pressure sensitivity completely for any brushes that use an anchored stroke type by default to fix the issue.
A further improvement would be to remove the pressure sensitivity button from those brushes as well.

Later on we could revisit D6603 to add pressure sensitivity to anchored brushes properly.

I tested [D12568](https://archive.blender.org/developer/D12568) and it doesn't fix the issue. We should disable pressure sensitivity completely for any brushes that use an anchored stroke type by default to fix the issue. A further improvement would be to remove the pressure sensitivity button from those brushes as well. Later on we could revisit [D6603](https://archive.blender.org/developer/D6603) to add pressure sensitivity to anchored brushes properly.

Philipp Oeser commented

2022-10-12 15:13:12 +02:00

In #83697#1361207, @JulienKaspar wrote:
We should disable pressure sensitivity completely for any brushes that use an anchored stroke type by default to fix the issue.

You mean Anchored Stroke Method? afaict, there are no (sculpt) brushes that use this by default (Rotate isnt, nor is Grab or Snake Hook)
Or would you mean disabling/hiding this for any brush that has Anchored Stroke Method enabled at any time? (doesnt seem to be used in that case, so might make sense)
Or do you just mean Grab, Snake Hook & Rotate?
There is another set of brushes (internally detected by sculpt_is_grab_tool)

SCULPT_TOOL_GRAB, doesnt use pressure, already has the pressure sensitivity hidden
SCULPT_TOOL_ELASTIC_DEFORM, doesnt use pressure (shows the setting in the UI though)
SCULPT_TOOL_POSE, doesnt use pressure (shows the setting in the UI though)
SCULPT_TOOL_BOUNDARY, doesnt use pressure (shows the setting in the UI though)
SCULPT_TOOL_THUMB, uses pressure sensitivity [but only the pressure from the start of the stroke, same as Rotate it seems]
SCULPT_TOOL_ROTATE, uses pressure [but problematic as desribed in this report]
SCULPT_TOOL_SNAKE_HOOK doesnt use pressure, already has the pressure sensitivity hidden

So if we could define which ones really should not use pressure (not even the one from the start of the stroke), we could easily tweak brush_strength in sculpt.c to not use it.

A further improvement would be to remove the pressure sensitivity button from those brushes as well.

The UI part we can control via BrushCapabilitiesSculpt_has_strength_pressure_get

> In #83697#1361207, @JulienKaspar wrote: > We should disable pressure sensitivity completely for any brushes that use an anchored stroke type by default to fix the issue. You mean `Anchored` `Stroke Method`? afaict, there are no (sculpt) brushes that use this by default (`Rotate` isnt, nor is `Grab` or `Snake Hook`) Or would you mean disabling/hiding this for any brush that has `Anchored` `Stroke Method` enabled at any time? (doesnt seem to be used in that case, so might make sense) Or do you just mean `Grab`, `Snake Hook` & `Rotate`? There is another set of brushes (internally detected by `sculpt_is_grab_tool`) - `SCULPT_TOOL_GRAB`, doesnt use pressure, already has the pressure sensitivity hidden - `SCULPT_TOOL_ELASTIC_DEFORM`, doesnt use pressure (shows the setting in the UI though) - `SCULPT_TOOL_POSE`, doesnt use pressure (shows the setting in the UI though) - `SCULPT_TOOL_BOUNDARY`, doesnt use pressure (shows the setting in the UI though) - `SCULPT_TOOL_THUMB`, uses pressure sensitivity [but only the pressure from the start of the stroke, same as Rotate it seems] - `SCULPT_TOOL_ROTATE`, uses pressure [but problematic as desribed in this report] - `SCULPT_TOOL_SNAKE_HOOK` doesnt use pressure, already has the pressure sensitivity hidden So if we could define which ones really should not use pressure (not even the one from the start of the stroke), we could easily tweak `brush_strength` in sculpt.c to not use it. > A further improvement would be to remove the pressure sensitivity button from those brushes as well. The UI part we can control via `BrushCapabilitiesSculpt_has_strength_pressure_get`

Philipp Oeser commented

2022-10-12 15:29:27 +02:00

The UI part we can control via BrushCapabilitiesSculpt_has_strength_pressure_get

Oh, and shouldnt we also use paint_supports_dynamic_size to define the same thing for radius pressure sensitivity capabilities as well?
So only show the pressure sensitivity for tools that actually use it (these are the same candidates: not for Anchored strokes, not for the sculpt_is_grab_tool brushes mentioned above)?

> The UI part we can control via BrushCapabilitiesSculpt_has_strength_pressure_get Oh, and shouldnt we also use `paint_supports_dynamic_size` to define the same thing for radius pressure sensitivity capabilities as well? So only show the pressure sensitivity for tools that actually use it (these are the same candidates: not for Anchored strokes, not for the `sculpt_is_grab_tool` brushes mentioned above)?

Philipp Oeser commented

2022-10-12 15:39:22 +02:00

additional note: once done, we should also cleanup the BRUSH_ALPHA_PRESSURE / BRUSH_SIZE_PRESSURE default flags for the brushes in the default startup as well as BKE_brush_sculpt_reset

additional note: once done, we should also cleanup the `BRUSH_ALPHA_PRESSURE` / `BRUSH_SIZE_PRESSURE` default flags for the brushes in the default startup as well as `BKE_brush_sculpt_reset`

Philipp Oeser self-assigned this 2022-10-13 09:17:46 +02:00

Philipp Oeser commented

2022-10-13 09:17:46 +02:00

Since I have already been looking at this (and also have #101769 on my table) I think it makes sense to reclaim

Julien Kaspar commented

2022-10-13 14:58:56 +02:00

@lichtwerk That sounds great! The brushes that you've listed should not use pressure sensitivity for size and pressure at all, and should have the toggle hidden in the UI.

Falk David commented

2022-10-13 15:58:24 +02:00

Removed subscriber: @filedescriptor

Philipp Oeser removed the

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Rotate sculpting brush may have an incorrect pen pressure behavior #83697