GPencil: Brush and stroke size related issues #85204

New Issue

Falk David · 2021-01-29T17:16:15+01:00

Falk David commented

2021-01-29 17:16:15 +01:00

Description

When drawing in grease pencil, control over the brush size and the thickness of the stroke is of course extremely important. Currently, there are some inconsistencies and confusing behavior that need to be addressed. Here is a list of current issues and some new proposals.

Brush Radius: Currently, the brush size can be changed via this slider in draw mode. The name displays "Radius" and the tooltip reads "Radius of the brush in pixels.", but this is not consistent with the thickness of the strokes. If the user sets the radius to 100px and the Stroke Thickness option in the object data properties is set to Screen Space the stroke has a diameter of 100 pixels. If the Stroke Thickness is set to World Space the stroke has a diameter of 0.1 meters. A simple solution is to change the UI name from "Radius" to "Size" and clarify in the tooltip that the thickness or diameter of the stroke is meant.
Radial Control: When the user changes the brush size via the radial control (shortcut {key F}) the control has a radius of the given pixel value, not (like mentioned before) a diameter of the pixel value set.
Brush size in World Space When the Stroke Thickness in the object data properties is set to World Space the displayed thickness of the strokes in that grease pencil object are calculated via the following formula: ((line_change + stroke_thickness) * pressure * pixel_factor) / 1000.0f E.g. when all adjustment values are set to their default value then 1px (stroke thickness) = 1mm (world space). Currently, there is no way for the user to know this. The UI gives no indication of this and the manual also does not mention it. A possible solution is to change the units of the brush from pixels to meters and also do the right conversion so that the size is correctly displayed in the UI.
Drawing in screen space/world space: The user can change the stroke thickness (screen space/world space) in the object data properties. That means that all strokes in the grease pencil object will be either drawn using the screen space thickness in pixels or the world space thickness in meters. But there is currently not a way to choose the brush size to be in screen or world space. In sculpt mode, the user can choose the brush size "reference" (Radius Unit). This would also be useful for grease pencil.

Brush size indicator: At the moment there is no visual feedback on how big the current brush is. A solution could be a "ring" around the cursor and deactivate it during drawing so it only shows up before starting the stroke.

Related reports:
#83675,

**Description** When drawing in grease pencil, control over the brush size and the thickness of the stroke is of course extremely important. Currently, there are some inconsistencies and confusing behavior that need to be addressed. Here is a list of current issues and some new proposals. - **Brush Radius:** Currently, the brush size can be changed via this slider in draw mode. ![image.png](https://archive.blender.org/developer/F9603762/image.png) The name displays "Radius" and the tooltip reads "Radius of the brush in pixels.", but this is not consistent with the thickness of the strokes. If the user sets the **radius** to 100px and the *Stroke Thickness* option in the object data properties is set to *Screen Space* the stroke has a **diameter** of 100 pixels. If the *Stroke Thickness* is set to *World Space* the stroke has a **diameter** of 0.1 meters. A simple solution is to change the UI name from "Radius" to "Size" and clarify in the tooltip that the thickness or diameter of the stroke is meant. - **Radial Control:** When the user changes the brush size via the radial control (shortcut {key F}) the control has a **radius** of the given pixel value, not (like mentioned before) a **diameter** of the pixel value set. ![brush_size_overlay.png](https://archive.blender.org/developer/F9603765/brush_size_overlay.png) - **Brush size in World Space** When the *Stroke Thickness* in the object data properties is set to *World Space* the displayed thickness of the strokes in that grease pencil object are calculated via the following formula: `((line_change + stroke_thickness) * pressure * pixel_factor) / 1000.0f` E.g. when all adjustment values are set to their default value then **1px (stroke thickness) = 1mm (world space)**. Currently, there is no way for the user to know this. The UI gives no indication of this and the manual also does not mention it. A possible solution is to change the units of the brush from pixels to meters and also do the right conversion so that the size is correctly displayed in the UI. - **Drawing in screen space/world space:** The user can change the stroke thickness (screen space/world space) in the object data properties. That means that *all* strokes in the grease pencil object will be either drawn using the screen space thickness in pixels or the world space thickness in meters. But there is currently not a way to choose the brush size to be in screen or world space. In sculpt mode, the user can choose the brush size "reference" (Radius Unit). ![brush_size_units.png](https://archive.blender.org/developer/F9604067/brush_size_units.png) This would also be useful for grease pencil. # **Brush size indicator:** At the moment there is no visual feedback on how big the current brush is. A solution could be a "ring" around the cursor and deactivate it during drawing so it only shows up before starting the stroke. --- **Related reports:** #83675,

Falk David self-assigned this 2021-01-29 17:16:15 +01:00

Falk David commented

2021-01-29 17:16:15 +01:00

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

Falk David commented

2021-01-29 17:16:15 +01:00

Added subscribers: @filedescriptor, @mendio, @pepe-school-land, @antoniov

Dalai Felinto changed title from ~~GPencil: Brush and stroke size relateted issues~~ to GPencil: Brush and stroke size related issues

2021-02-02 17:48:44 +01:00

Nick Alberelli commented

2022-03-15 15:58:37 +01:00

Added subscriber: @TinyNick

patrick gaunt commented

2022-04-27 15:15:07 +02:00

Added subscriber: @paddygaunt

patrick gaunt commented

2022-04-27 15:15:07 +02:00

I think the lack of any meaningful correspondence between the brush diameter set using F and the actual stroke diameter is a real impediment to sketching and painting with grease pencil (c.f. sculpting and texture painting). I can see that there are issues with converting the brush diameter into a diameter for each vertex and its apparent size changing with Z distance...

However, when you draw with grease pencil, the stroke produced until the mouse button is release appears to be fixed radius based on the Z distance of the origin, 3D cursor etc. When the mouse button is release the stroke is displayed correctly. Could the brush diameter when pressing F use the same approximation?

I think the lack of any meaningful correspondence between the brush diameter set using F and the actual stroke diameter is a real impediment to sketching and painting with grease pencil (c.f. sculpting and texture painting). I can see that there are issues with converting the brush diameter into a diameter for each vertex and its apparent size changing with Z distance... However, when you draw with grease pencil, the stroke produced until the mouse button is release appears to be fixed radius based on the Z distance of the origin, 3D cursor etc. When the mouse button is release the stroke is displayed correctly. Could the brush diameter when pressing F use the same approximation?

Philipp Oeser removed the

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GPencil: Brush and stroke size related issues #85204

Brush size indicator: At the moment there is no visual feedback on how big the current brush is. A solution could be a "ring" around the cursor and deactivate it during drawing so it only shows up before starting the stroke.