Grease pencil cutter tool doesn't reliably terminate lines where they intersect #78786

New Issue

Tomasz Kaye · 2020-07-10T11:40:09+02:00

Tomasz Kaye commented

2020-07-10 11:40:09 +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
Grease pencil cutter tool doesn't reliably terminate lines where they intersect

Exact steps for others to reproduce the error
Load the attached blend file.

Use the cutter to drag around the green area of the top line. A new point is added, but the line's terminated too early. Leaving a lump on the 'cutter side' of the intersection.

Undo. And drag the cutter tool around the red area of the bottom line. A new point is added, but the line's terminated too late. Leaving a small gap on the other side of the intersection.

Expected behaviour: The cutter tool adds a new point exactly on the intersection with the second line and deletes points up to that new point.

cutterproblem.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** Grease pencil cutter tool doesn't reliably terminate lines where they intersect **Exact steps for others to reproduce the error** Load the attached blend file. ![Screenshot 2020-07-10 at 11.25.13.png](https://archive.blender.org/developer/F8683235/Screenshot_2020-07-10_at_11.25.13.png) Use the cutter to drag around the green area of the top line. A new point is added, but the line's terminated too early. Leaving a lump on the 'cutter side' of the intersection. ![Screenshot 2020-07-10 at 11.25.29.png](https://archive.blender.org/developer/F8683237/Screenshot_2020-07-10_at_11.25.29.png) Undo. And drag the cutter tool around the red area of the bottom line. A new point is added, but the line's terminated too late. Leaving a small gap on the other side of the intersection. ![Screenshot 2020-07-10 at 11.25.40.png](https://archive.blender.org/developer/F8683242/Screenshot_2020-07-10_at_11.25.40.png) Expected behaviour: The cutter tool adds a new point exactly on the intersection with the second line and deletes points up to that new point. [cutterproblem.blend](https://archive.blender.org/developer/F8683244/cutterproblem.blend)

Tomasz Kaye commented

2020-07-10 11:40:09 +02:00

Added subscriber: @info-27

Antonio Vazquez commented

2020-07-10 13:23:45 +02:00

Added subscribers: @filedescriptor, @antoniov

Antonio Vazquez commented

2020-07-10 13:23:45 +02:00

This actually is a limitation of the algorithm used. If you look at your example file, there isn't geometry near of the intersection. The algorithm needs some point more or less near of cut position. If you subdivide and add a point, you will see the cutter works better.

Thanks for your report, but as now we haven't time and resources to work in the improvement of this tool, we are going to consider as a Know Issue that could be improved in the future with a better cutter algorithm.

@filedescriptor I think some of your algorithms could be used here.

This actually is a limitation of the algorithm used. If you look at your example file, there isn't geometry near of the intersection. The algorithm needs some point more or less near of cut position. If you subdivide and add a point, you will see the cutter works better. Thanks for your report, but as now we haven't time and resources to work in the improvement of this tool, we are going to consider as a Know Issue that could be improved in the future with a better cutter algorithm. @filedescriptor I think some of your algorithms could be used here.

Falk David commented

2020-07-10 13:31:18 +02:00

@antoniov Indeed. This can be solved with the boolean algorithms. For now, it is a limitation.