Knife tool cut preview line becomes black. #59505

New Issue

Eugene Kostyuk · 2018-12-17T19:21:24+01:00

Eugene Kostyuk commented

2018-12-17 19:21:24 +01:00

System Information
Operating system:Windows 10 x64
Graphics card:GTX 1050ti

Blender Version
Broken: blender2.8 beta, December17 02:51:21, 9149e89421

Short description of error
While using the knife tool, the preview line of the cut seems to be randomly changing it`s color to black.
Exact steps for others to reproduce the error
In edit mode, press k to switch to knife tool. Begin a cut. End cut with a spacebar. The next cut line might appear black. I also pressed undo button, and the line appeared black when i started a new cut. The other time it was normal. I could not see a regularity here.

**System Information** Operating system:Windows 10 x64 Graphics card:GTX 1050ti **Blender Version** Broken: blender2.8 beta, December17 02:51:21, 9149e894210 **Short description of error** While using the knife tool, the preview line of the cut seems to be randomly changing it`s color to black. **Exact steps for others to reproduce the error** In edit mode, press k to switch to knife tool. Begin a cut. End cut with a spacebar. The next cut line might appear black. I also pressed undo button, and the line appeared black when i started a new cut. The other time it was normal. I could not see a regularity here. ![Screenshot_4.png](https://archive.blender.org/developer/F5983082/Screenshot_4.png) ![Screenshot_5.png](https://archive.blender.org/developer/F5983085/Screenshot_5.png)

Eugene Kostyuk commented

2018-12-17 19:21:24 +01:00

Added subscriber: @EugeneKostyuk

Sebastian Parborg commented

2018-12-21 12:09:36 +01:00

Added subscriber: @ZedDB

Sebastian Parborg commented

2018-12-21 12:09:36 +01:00

I can not reproduce this on the default cube scene with a build from today. Could you try a recent build from https://builder.blender.org/download/ and see if you stil get this issue?

Also be sure that you have the latest GPU drivers for your card.

I can not reproduce this on the default cube scene with a build from today. Could you try a recent build from https://builder.blender.org/download/ and see if you stil get this issue? Also be sure that you have the latest GPU drivers for your card.

Eugene Kostyuk commented

2018-12-21 12:58:29 +01:00

Hi! I checked the drivers they were up to date. In latest build 9dde3e42a7 loaded the factory settings. Had no bugged result on a default cube ( tried 10 times in a row, or so ). But then created a new plane, changed it`s position, entered the edit mode and the first cut was black. Every newly created plane had same result (at the most). First cut is black, second one is normal.

Hi! I checked the drivers they were up to date. In latest build 9dde3e42a7c5 loaded the factory settings. Had no bugged result on a default cube ( tried 10 times in a row, or so ). But then created a new plane, changed it`s position, entered the edit mode and the first cut was black. Every newly created plane had same result (at the most). First cut is black, second one is normal.

Sebastian Parborg commented

2018-12-21 13:55:46 +01:00

I still can't seem to reproduce this with a plane. Could you provide a .blend file where you can easily reproduce this? IE:

Open blend file
Cut with knife
Black knife cut

I still can't seem to reproduce this with a plane. Could you provide a .blend file where you can easily reproduce this? IE: 1. Open blend file 2. Cut with knife 3. Black knife cut

Eugene Kostyuk commented

2018-12-21 14:10:19 +01:00

{F6025608}knife_example.blend
Attached a file. Steps to reproduce:
1.delete a cube
2.create a new one
3.cut with a knife

A bug shows itself in the process, when you have not yet finished the cut with spacebar or enter key.
It repeats often, not 100% times though.
Been able to reproduce this bug on a different pc at work.

Hope this helps.

{[F6025608](https://archive.blender.org/developer/F6025608/Screenshot_1.jpg)}[knife_example.blend](https://archive.blender.org/developer/F6025561/knife_example.blend) Attached a file. Steps to reproduce: 1.delete a cube 2.create a new one 3.cut with a knife A bug shows itself in the process, when you have not yet finished the cut with spacebar or enter key. It repeats often, not 100% times though. Been able to reproduce this bug on a different pc at work. Hope this helps.

Sebastian Parborg commented

2018-12-21 14:17:26 +01:00

Added subscriber: @fclem

Sebastian Parborg commented

2018-12-21 14:17:26 +01:00

Nope, still can reproduce this... :C

I'm guessing this is a GPU/Windows specific bug or something.

@fclem any ideas?

Nope, still can reproduce this... :C I'm guessing this is a GPU/Windows specific bug or something. @fclem any ideas?

Eugene Kostyuk commented

2018-12-21 14:29:35 +01:00

My system at work: Windows 10 pro 64 bit. GTX 650ti.
System at home: Windows 10 pro 64 bit. GTX 1050ti.
Both have 8 gigs of ram.

My system at work: Windows 10 pro 64 bit. GTX 650ti. System at home: Windows 10 pro 64 bit. GTX 1050ti. Both have 8 gigs of ram.

Clément Foucault was assigned by Sebastian Parborg

2018-12-21 14:50:12 +01:00

Sebastian Parborg commented

2018-12-21 14:50:12 +01:00

You might as well try to run blender with --debug-gpu and attach the output here (Run blender from cmd with blender.exe --debug-gpu > output.txt and attach output.txt after you have reproduced the black line issue)

You can also try to run with --debug-gpu-force-workarounds and see if that helps.

You might as well try to run blender with `--debug-gpu` and attach the output here (Run blender from cmd with `blender.exe --debug-gpu > output.txt` and attach output.txt after you have reproduced the black line issue) You can also try to run with `--debug-gpu-force-workarounds` and see if that helps.

Eugene Kostyuk commented

2018-12-21 15:27:29 +01:00

video_debug.txt

With debug on. The last cut action was bugged.

[video_debug.txt](https://archive.blender.org/developer/F6026089/video_debug.txt) With debug on. The last cut action was bugged.

Eugene Kostyuk commented

2018-12-21 15:31:36 +01:00

Strange. With debug on i barely was able to catch this bug.
With no debug it was 100% reproducable.
Used c9df453ce7 build for debugging.

Strange. With debug on i barely was able to catch this bug. With no debug it was 100% reproducable. Used c9df453ce70b build for debugging.

Clément Foucault commented

2018-12-21 16:18:32 +01:00

I can reproduce: