"Stabilize Stroke" settings are implicitly relative to Spacing #116468

New Issue

Julien Kaspar · 2023-12-22T15:37:44+01:00

Julien Kaspar commented

2023-12-22 15:37:44 +01:00

(Edited this description as a summary)

Short description of error
The values for the Stabilize Stroke brush settings are labeled Radius and Factor.
The presentation implies that the Radius is used to set the distance of the Stabilized Stroke delay.
This is not true. The distance is calculated by using the Spacing, which is relative to the brush radius and interpolating the previous stroke position and the mouse position via the Factor.

This is confusing and counter intuitive. A value to set the distance is missing. This shouldn't be hard coded to be dependant on the Spacing value.

Using the Radius to increase the distance is not leading to any perceivable results or to choppy strokes.

The Factor should be instead described or named as a Stiffness factor, because higher values lead to an increased rubber band effect. This would ideally also involve changes to the implementation to prevent higher values from increasing the distance.

(Edited this description as a summary) **Short description of error** The values for the Stabilize Stroke brush settings are labeled Radius and Factor. The presentation implies that the Radius is used to set the distance of the Stabilized Stroke delay. This is not true. The distance is calculated by using the Spacing, which is relative to the brush radius and interpolating the previous stroke position and the mouse position via the Factor. ![image](/attachments/f30ebb90-0776-4d47-9f1c-08ed5477724f) This is confusing and counter intuitive. A value to set the distance is missing. This shouldn't be hard coded to be dependant on the Spacing value. Using the Radius to increase the distance is not leading to any perceivable results or to choppy strokes. The Factor should be instead described or named as a Stiffness factor, because higher values lead to an increased rubber band effect. This would ideally also involve changes to the implementation to prevent higher values from increasing the distance.

image.png

25 KiB

Julien Kaspar added the

labels 2023-12-22 15:37:44 +01:00

Germano Cavalcante commented

2023-12-26 16:55:59 +01:00

The two main commits I found about this were:
a5da26f59d (2.5/Sculpt:)
0fabb2039b (2.5/Sculpt: == Re-added smooth stroke ==)

Both from @NicholasBishop

The explanation of "Factor" and "Radius" can be seen here:

The stroke interpolates between the last mouse location and the current location, weighted towards the previous location. If the stroke gets within a certain radius of the current mouse location, the stroke stops. This radius allows for sharp turns in the stroke.

So, from what you can understand, the Factor is the interpolation value of the initial mouse position (where the stroke would be drawn) and the actual current mouse position.

If the Factor is the minimum, 0.5, the calculated position for the brush is at position 0.5 between {mouse_position} and {last_mouse_position}, that is, in the middle.

If the Factor is the maximum, 0.99, the position is very close to {last_mouse_position}, so you need to move the mouse much more so that the calculated position for the brush exceeds the spacing distance (default 10% of the Brush radius).

The "Radius" value of "Stabilize Stroke" indicates the minimum distance between {mouse_position} and {last_mouse_position} to start drawing.
Since the default combination of Spacing (10%) and Factor (0.75) causes the drawing distance of spacing to exceed the minimum, this "Radius" value is hardly observable. You would need to set small Spacing and Factor values for "Radius" to take effect.

This does not appear to be a bug as it is not clear how to fix the problem.

The two main commits I found about this were: https://projects.blender.org/blender/blender/commit/a5da26f59d8cd820ca4d27a06028dd6aaee65784 (2.5/Sculpt:) https://projects.blender.org/blender/blender/commit/0fabb2039b3e85ae7b7b712e5dc1b7ba22929440 (2.5/Sculpt: == Re-added smooth stroke ==) Both from @NicholasBishop The explanation of "Factor" and "Radius" can be seen here: > The stroke interpolates between the last mouse location and the current location, weighted towards the previous location. If the stroke gets within a certain radius of the current mouse location, the stroke stops. This radius allows for sharp turns in the stroke. So, from what you can understand, the Factor is the interpolation value of the initial mouse position (where the stroke would be drawn) and the actual current mouse position. If the Factor is the minimum, 0.5, the calculated position for the brush is at position 0.5 between {mouse_position} and {last_mouse_position}, that is, in the middle. If the Factor is the maximum, 0.99, the position is very close to {last_mouse_position}, so you need to move the mouse much more so that the calculated position for the brush exceeds the spacing distance (default 10% of the Brush radius). The "Radius" value of "Stabilize Stroke" indicates the minimum distance between {mouse_position} and {last_mouse_position} to start drawing. Since the default combination of Spacing (10%) and Factor (0.75) causes the drawing distance of spacing to exceed the minimum, this "Radius" value is hardly observable. You would need to set small Spacing and Factor values for "Radius" to take effect. --- This does not appear to be a bug as it is not clear how to fix the problem.

Germano Cavalcante added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2023-12-26 17:05:10 +01:00

Julien Kaspar commented

2024-01-02 09:54:38 +01:00

Good to know that this is not a bug. Although, yes, the explanation highlights how nonsensical the UI is and tooltips are. The Radius seems to be the primary value but has next to no effect with the default factor of 0.9 ... which is backwards logic in multiple ways.

It's completely missing from the tooltips and manual that the distance of the Stabilized Stroke is relative to the Spacing distance (for example 20% of the Radius if the Spacing is set to 10% and the Factor to 0.5)
Once the Factor is increased this becomes increasingly hard to predict.

I'll chat with module devs about this. Thanks for investigating anyway!

Good to know that this is not a bug. Although, yes, the explanation highlights how nonsensical the UI is and tooltips are. The Radius seems to be the primary value but has next to no effect with the default factor of 0.9 ... which is backwards logic in multiple ways. It's completely missing from the tooltips and manual that the distance of the Stabilized Stroke is relative to the Spacing distance (for example 20% of the Radius if the Spacing is set to 10% and the Factor to 0.5) Once the Factor is increased this becomes increasingly hard to predict. I'll chat with module devs about this. Thanks for investigating anyway!

Julien Kaspar closed this issue

2024-01-02 09:54:40 +01:00

Blender Bot added

Status

Archived

and removed

Status

Needs Information from User

labels 2024-01-02 09:54:42 +01:00

Julien Kaspar commented

2024-01-02 14:59:25 +01:00

I talked with @Sergey and he suggested to keep this as a known issue.

The problem here is that the settings are working as intended but the result is not predictable nor very useful.
Ideally the Distance should not be dependent on the Spacing of the stroke but offer another value to set a distance factor based on the brush Radius.

Otherwise the Radius value will be assumed to to be the distance. But if the user increases this value, the stroke will become more 'choppy'. It increases the minimum distance when the stroke is updated and applying the spaced dots along broken lines.

By default when the Factor is set to 0.9, the Radius will not have any perceivable effect.

I talked with @Sergey and he suggested to keep this as a known issue. The problem here is that the settings are working as intended but the result is not predictable nor very useful. Ideally the Distance should not be dependent on the Spacing of the stroke but offer another value to set a distance factor based on the brush Radius. Otherwise the Radius value will be assumed to to be the distance. But if the user increases this value, the stroke will become more 'choppy'. It increases the minimum distance when the stroke is updated and applying the spaced dots along broken lines. ![image](/attachments/004dcbb9-e4ce-4da8-a6db-9be3c096cd9b) By default when the Factor is set to 0.9, the Radius will not have any perceivable effect.

image.png

461 KiB

Julien Kaspar reopened this issue

2024-01-02 14:59:28 +01:00

Blender Bot added

and removed

labels 2024-01-02 14:59:30 +01:00

Julien Kaspar added

Type

Known Issue

Module

Sculpt, Paint & Texture

and removed

labels 2024-01-02 15:00:18 +01:00

Julien Kaspar changed title from ~~"Stabilize Stroke" settings have wrong/unclear naming~~ to "Stabilize Stroke" settings are implicitly relative to Spacing

2024-01-04 10:42:27 +01:00

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

"Stabilize Stroke" settings are implicitly relative to Spacing #116468