GPencil: When cancel a extrude point, the point is not removed and creates two points on same location #79256

New Issue

Tomasz Kaye · 2020-07-25T11:51:04+02:00

Tomasz Kaye commented

2020-07-25 11:51:04 +02:00

System Information
Operating system: Darwin-19.3.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.5.5

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-28 15:13, hash: b21ba5e579

Short description of error
When a GPencil point at the end of a stroke is extruded, but the extrusion operation is cancelled before committing it, the Custom Curve of the thickness modifier seems to treat the stroke as though the cancelled point exists (the end of the stroke doesn't have the expected thickness applied by the modifier)

Exact steps for others to reproduce the error

Open attached blend file
In draw mode, do a momentary click to add a new stroke with a single point, beneath the other strokes.
In edit mode select the new point and press E to extrude. Move the extruded point to the right and confirm the operation.
Repeatedly extrude the newest point until there are four points
Begin to extrude a 5th point in the same way, move the extruded point to the right, but instead of clicking to confirm, press Escape to cancel the extrusion.
Now the thickness at the right-hand end of the stroke is being set incorrectly by the Thickness modifier.

thicknessextrudebug.blend

**System Information** Operating system: Darwin-19.3.0-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.5.5 **Blender Version** Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-28 15:13, hash: `b21ba5e579` **Short description of error** When a GPencil point at the end of a stroke is extruded, but the extrusion operation is cancelled before committing it, the Custom Curve of the thickness modifier seems to treat the stroke as though the cancelled point exists (the end of the stroke doesn't have the expected thickness applied by the modifier) ![Screenshot 2020-07-25 at 11.46.34.png](https://archive.blender.org/developer/F8719627/Screenshot_2020-07-25_at_11.46.34.png) **Exact steps for others to reproduce the error** * Open attached blend file * In draw mode, do a momentary click to add a new stroke with a single point, beneath the other strokes. * In edit mode select the new point and press E to extrude. Move the extruded point to the right and confirm the operation. * Repeatedly extrude the newest point until there are four points * Begin to extrude a 5th point in the same way, move the extruded point to the right, but instead of clicking to confirm, press Escape to cancel the extrusion. * Now the thickness at the right-hand end of the stroke is being set incorrectly by the Thickness modifier. [thicknessextrudebug.blend](https://archive.blender.org/developer/F8719629/thicknessextrudebug.blend)

Tomasz Kaye commented

2020-07-25 11:51:04 +02:00

Added subscriber: @info-27

Antonio Vazquez commented

2020-07-25 17:27:02 +02:00

Added subscriber: @antoniov

Antonio Vazquez commented

2020-07-25 17:27:02 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Antonio Vazquez commented

2020-07-25 17:27:02 +02:00

The thickness modifier is working as expected, but the stroke has 2 points on the same coordinates.

I need review when you escape the extrude to Undo the created point. It looks is undoing the posicion, but must remove the point.

The thickness modifier is working as expected, but the stroke has 2 points on the same coordinates. ![image.png](https://archive.blender.org/developer/F8719957/image.png) I need review when you escape the extrude to Undo the created point. It looks is undoing the posicion, but must remove the point.

Antonio Vazquez changed title from ~~GPencil. Thickness modifier gives incorrect result if point extrude operation is cancelled~~ to GPencil: When cancel a extrude point, the point is not removed and creates two points on same location

2020-07-25 17:27:34 +02:00

Antonio Vazquez commented

2020-07-25 17:40:16 +02:00

Changed status from 'Needs Developer To Reproduce' to: 'Archived'

Antonio Vazquez closed this issue

2020-07-25 17:40:16 +02:00

Antonio Vazquez self-assigned this 2020-07-25 17:40:16 +02:00

Antonio Vazquez commented

2020-07-25 17:40:16 +02:00

I have been looking at code and how works a mesh and it has the same issue. If you add a mesh plane, and extrude one vertex and cancel, the vertex is added (now the plane has 5 vertex) but it's in the same location.

The problem is when you extrude (a mesh or a gpencil), you are executing two operatos, first the add point (this cannot be canceled) and later the transform (this can be canceled). As you extruded, but canceled the transform, really you only executed the first operator (add point). In your example, as both points are on the same position in the extreme of the stroke, the thickness modifier cannot calculate propertly the result.

As this is by design and due the internal design of the transform operators (not only for GPencil), we can consider this report is not a bug, but a design limitation in general, so I'm going to close it.

I have been looking at code and how works a mesh and it has the same issue. If you add a mesh plane, and extrude one vertex and cancel, the vertex is added (now the plane has 5 vertex) but it's in the same location. The problem is when you extrude (a mesh or a gpencil), you are executing two operatos, first the add point (this cannot be canceled) and later the transform (this can be canceled). As you extruded, but canceled the transform, really you only executed the first operator (add point). In your example, as both points are on the same position in the extreme of the stroke, the thickness modifier cannot calculate propertly the result. As this is by design and due the internal design of the transform operators (not only for GPencil), we can consider this report is not a bug, but a design limitation in general, so I'm going to close it.

Tomasz Kaye commented

2020-07-25 18:08:32 +02:00

Thanks for the explanation. that helps me find a workaround for my use case.

In the case of a cancelled extrude, could Blender delete the newly created point(s) vertex(es)? or is there some case where you'd want them to remain there?

Thanks for the explanation. that helps me find a workaround for my use case. In the case of a cancelled extrude, could Blender delete the newly created point(s) vertex(es)? or is there some case where you'd want them to remain there?

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GPencil: When cancel a extrude point, the point is not removed and creates two points on same location #79256