Grease Pencil Line Art trouble with overlapping edges in orthographic views #86730

New Issue

Marco Ferrara · 2021-03-19T09:20:35+01:00

Marco Ferrara commented

2021-03-19 09:20:35 +01:00

System Information
Operating system: Linux-5.8.0-44-generic-x86_64-with-glibc2.31 64 Bits
Graphics card: GeForce GTX 1060 3GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-03-18 21:29, hash: 36deb8a48e

Short description of error
Grease pencil Line art modifier seems to have some trouble generating strokes for orthographic cameras if source object contains faces that are perpendicular to the camera.
The problem seems related to the edges that overlap in an orthographic projection and tends to disappear if a tiny rotation is applied to the object (or to the edges).

Exact steps for others to reproduce the error

In the default scene select the camera, change its type to Orthographic and clear its rotation to make its Z axis parallel to the scene Z axis (like a Top view)
Move the camera on top of the default cube (in order to frame it)
Create a Grease pencil Object Line art with the default Cube as source (but you can create a Collection or a Scene Line art as well)
No stroke appears...
...unless you rotate the cube (even of a very slight amount, like 0.0001° for every axis) or explode every face in a separate object (applying an Edge split modifier to the cube is not enough)

{F9899207, size=full}

GP_Line_Art_bug.blend

Thanks!

**System Information** Operating system: Linux-5.8.0-44-generic-x86_64-with-glibc2.31 64 Bits Graphics card: GeForce GTX 1060 3GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.39 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-03-18 21:29, hash: `36deb8a48e` **Short description of error** Grease pencil Line art modifier seems to have some trouble generating strokes for orthographic cameras if source object contains faces that are perpendicular to the camera. The problem seems related to the edges that overlap in an orthographic projection and tends to disappear if a tiny rotation is applied to the object (or to the edges). **Exact steps for others to reproduce the error** - In the default scene select the camera, change its type to Orthographic and clear its rotation to make its Z axis parallel to the scene Z axis (like a Top view) - Move the camera on top of the default cube (in order to frame it) - Create a Grease pencil Object Line art with the default Cube as source (but you can create a Collection or a Scene Line art as well) - No stroke appears... ...unless you rotate the cube (even of a very slight amount, like 0.0001° for every axis) or explode every face in a separate object (applying an Edge split modifier to the cube is not enough) {[F9899207](https://archive.blender.org/developer/F9899207/Screenshot_from_2021-03-19_09-14-46.png), size=full} [GP_Line_Art_bug.blend](https://archive.blender.org/developer/F9899209/GP_Line_Art_bug.blend) Thanks!

Marco Ferrara commented

2021-03-19 09:20:35 +01:00

Added subscriber: @MarcoFerrara

YimingWu commented

2021-03-20 06:18:51 +01:00

Added subscriber: @ChengduLittleA

YimingWu self-assigned this 2021-03-20 06:18:51 +01:00

YimingWu commented

2021-03-20 06:18:51 +01:00

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

YimingWu commented

2021-03-20 06:18:51 +01:00

Perpendicular faces to camera in Ortho view indeed have caused some problems in the past. I checked the file and confirmed the issue. Tried with edge split and other options combined It seems to me like a case where the internal algorithm had taken care of the problem but somehow discarded the lines. I'll see if I can fix it.

blender-admin commented

2021-03-20 06:35:13 +01:00

This issue was referenced by 3d5239ff40

This issue was referenced by 3d5239ff40e7dc072d8e9c93fdb53817586c9935

YimingWu commented

2021-03-20 06:40:10 +01:00

Changed status from 'Confirmed' to: 'Resolved'

YimingWu closed this issue

2021-03-20 06:40:10 +01:00

YimingWu commented

2021-03-20 06:40:10 +01:00

Fixed with commit 9db7c3db. The fix should be merged into master shortly.

Fixed with commit `9db7c3db`. The fix should be merged into master shortly.

Mauro Amoruso commented

2022-02-23 08:36:05 +01:00

Added subscriber: @Mauro_Amoruso

Mauro Amoruso commented

2022-02-23 08:36:05 +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

Feel is related to same Issue so not sure if I have to open a new Bug Report.

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) Feel is related to same Issue so not sure if I have to open a new Bug Report. Thanks

Philipp Oeser commented

2022-02-23 08:38:42 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-02-23 08:38:42 +01:00

In #86730#1312421, @Mauro_Amoruso wrote:
Feel is related to same Issue so not sure if I have to open a new Bug Report.

Please open a new report for this

> In #86730#1312421, @Mauro_Amoruso wrote: > Feel is related to same Issue so not sure if I have to open a new Bug Report. Please open a new report for this

Mauro Amoruso commented

2022-02-23 09:17:33 +01:00

Done https://developer.blender.org/T95984

YimingWu commented

2022-02-24 05:47:26 +01:00

Alright I'm taking a look for this.

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Grease Pencil Line Art trouble with overlapping edges in orthographic views #86730