Grease Pencil Line Art trouble with edges in Shifted Cameras in orthographic views #95984

New Issue

Mauro Amoruso · 2022-02-23T09:16:02+01:00

Mauro Amoruso commented

2022-02-23 09:16:02 +01:00

Grease Pencil Line Art trouble with edges in Shifted Cameras in orthographic views

System Information
Operating system: Ubuntu 20.04.3 LTS
Graphics card: NVIDIA Corporation GK208BM [GeForce 920M] / Mesa Intel® HD Graphics 5500 (BDW GT2)

Blender Version
version: blender-3.1.0-beta+v31.517afcc858b0-linux.x86_64-release

Short description of error

Grease pencil Line art modifier seems to have some trouble generating strokes for orthographic shifted cameras
The problem seems related to the edges in an orthographic projection and disappear when the camera is not shifted (set to default value 0)

Exact steps for others to reproduce the error

- In the default scene select the camera, change its type to Orthographic and shift the camera in any value.
- Create a Grease pencil Object Line art with the default Collection 
- strokes appears distorted or out of place

Line_art_issues_with_shifted_orthographic_camera.blend

Thanks

**Grease Pencil Line Art trouble with edges in Shifted Cameras in orthographic views** **System Information** Operating system: Ubuntu 20.04.3 LTS Graphics card: NVIDIA Corporation GK208BM [GeForce 920M] / Mesa Intel® HD Graphics 5500 (BDW GT2) **Blender Version** version: blender-3.1.0-beta+v31.517afcc858b0-linux.x86_64-release **Short description of error** Grease pencil Line art modifier seems to have some trouble generating strokes for orthographic **shifted** cameras The problem seems related to the edges in an orthographic projection and disappear when the camera is not shifted (set to default value 0) **Exact steps for others to reproduce the error** - In the default scene select the camera, change its type to Orthographic and shift the camera in any value. - Create a Grease pencil Object Line art with the default Collection - strokes appears distorted or out of place ![Before.png](https://archive.blender.org/developer/F12883779/Before.png) ![after.png](https://archive.blender.org/developer/F12883781/after.png) [Line_art_issues_with_shifted_orthographic_camera.blend](https://archive.blender.org/developer/F12883783/Line_art_issues_with_shifted_orthographic_camera.blend) Thanks

YimingWu was assigned by Mauro Amoruso

2022-02-23 09:16:02 +01:00

Mauro Amoruso commented

2022-02-23 09:16:02 +01:00

Added subscribers: @Mauro_Amoruso, @MarcoFerrara, @lichtwerk, @ChengduLittleA

Omar Emara commented

2022-02-23 09:18:51 +01:00

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

Mauro Amoruso commented

2022-02-23 09:26:07 +01:00

If the operator is implemented in Python, and someone can show me where is the implementation of this feature. I can give a try.

YimingWu commented

2022-02-24 05:45:58 +01:00

Thanks for the report. I'll take care of it. In the mean time could you try temp-lineart-contained branch and use the "ortho tolerance" option, see if it's any better? The camera projection is handled a little differently than master. I could port that option to master as a fix if it helps...

@Mauro_Amoruso It's in C, lineart_cpu.c.

Thanks for the report. I'll take care of it. In the mean time could you try `temp-lineart-contained` branch and use the "ortho tolerance" option, see if it's any better? The camera projection is handled a little differently than `master`. I could port that option to `master` as a fix if it helps... @Mauro_Amoruso It's in C, `lineart_cpu.c`.

Mauro Amoruso commented

2022-02-24 10:00:28 +01:00

@ChengduLittleA Thanks for your amazing work on this project, it really helps us all.

I have tried the same file with blender-3.1.0-alpha+temp-lineart-contained-linux.x86_64-release
it has different version of the same issues, and even when the Shift camera is 0 the problem appears (with or without ortho)

without Shifted camera with or without "ortho tolerance" (works in master 3.2 Beta)

with Shifted camera without "ortho tolerance"

with Shifted camera and with "ortho tolerance"

I tried play with Range or other stuff and it is not getting better even after regenerating the line art or creating a new cameras

@ChengduLittleA Thanks for your **amazing work** on this project, it really helps us all. I have tried the same file with blender-3.1.0-alpha+temp-lineart-contained-linux.x86_64-release it has different version of the same issues, and even when the Shift camera is 0 the problem appears (with or without ortho) without Shifted camera with or without "ortho tolerance" (works in master 3.2 Beta) ![alpha_issues.png](https://archive.blender.org/developer/F12885291/alpha_issues.png) with Shifted camera without "ortho tolerance" ![3.1Apha_build.png](https://archive.blender.org/developer/F12885271/3.1Apha_build.png) with Shifted camera and with "ortho tolerance" ![withorto.png](https://archive.blender.org/developer/F12885277/withorto.png) I tried play with Range or other stuff and it is not getting better even after regenerating the line art or creating a new cameras

YimingWu commented

2022-02-24 17:22:21 +01:00

EHHHH why is it broken even more.... I'll clear it out tomorrow.

YimingWu commented

2022-02-25 05:50:37 +01:00

Turns out some of the problem in temp-lineart-contained is caused by the back face culling bug that's already fixed in master. Without shifting stuff is working correctly.

However shifting gives me very weird result which doesn't really reflect how line art work. I need to investigate more

![图片.png](https://archive.blender.org/developer/F12886270/图片.png) Turns out some of the problem in `temp-lineart-contained` is caused by the back face culling bug that's already fixed in master. Without shifting stuff is working correctly. However shifting gives me very weird result which doesn't really reflect how line art work. I need to investigate more

blender-admin commented

2022-02-25 06:50:23 +01:00

This issue was referenced by e7cae51877

This issue was referenced by e7cae5187773f41e62830be597c6f598bff0653f

blender-admin commented

2022-02-25 06:50:23 +01:00

This issue was referenced by 60af7a3496

This issue was referenced by 60af7a349614f9ebe88ebb71f4c8fad14a0e274f

YimingWu commented

2022-02-25 06:53:05 +01:00

Alright, this is fixed now. It's the inconsistent geometry shifting that's causing the problem.

YimingWu commented

2022-02-25 07:09:31 +01:00

Changed status from 'Confirmed' to: 'Resolved'

YimingWu closed this issue

2022-02-25 07:09:31 +01:00

Mauro Amoruso commented

2022-02-25 08:26:34 +01:00

Wow so fast!

{meme, src=itsawesome}

. thanks, btw I saw the issue in the main lineart_main_perspective_division function and how the W values are actually looped instead of the Z, ones the patch is pushed I am going to test my "real" blend files.

Wow so fast! {meme, src=itsawesome} . thanks, btw I saw the issue in the main `lineart_main_perspective_division` function and how the W values are actually looped instead of the Z, ones the patch is pushed I am going to test my "real" blend files.

YimingWu commented

2022-02-25 12:56:00 +01:00

@Mauro_Amoruso The division is supposed to do xyz/w (z is non linear there), w is the linear distance to camera plane, thus div by w would give linear perspective effect.

Also you can already build it or wait for 3.1/3.2 daily build or lineart branch

@Mauro_Amoruso The division is supposed to do `xyz/w` (z is non linear there), `w` is the linear distance to camera plane, thus div by w would give linear perspective effect. Also you can already build it or wait for 3.1/3.2 daily build or lineart branch

Mauro Amoruso commented

2022-02-27 06:09:24 +01:00

@ChengduLittleA thanks for helping me understand the code! I wanted just to confirm that I checked the my most complex .blend files with new built and it is beautifully consistent even when using occlusion feature.

@ChengduLittleA thanks for helping me understand the code! I wanted just to confirm that I checked the my most complex .blend files with new built and it is beautifully consistent even when using `occlusion` feature.

YimingWu commented

2022-02-28 05:41:00 +01:00

@Mauro_Amoruso That's good to hear :)

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Grease Pencil Line Art trouble with edges in Shifted Cameras in orthographic views #95984