GPencil: Flickering when use Background or Camera image #76886

New Issue

John Grigni · 2020-05-19T17:43:00+02:00

John Grigni commented

2020-05-19 17:43:00 +02:00

System Information
Operating system: MacOS Catalina 10.15.4
iMac Retina 5K, late 2017
Graphics card: Radeon Pro 580 8GB

Blender Version
Broken: (2.83 beta)
Worked: (2.82a)

Short description of error
A grease pencil object with a build modifier flickers in opacity in some strokes of a multi-stroke object.
It occurs in the Sequential mode with Grow or Shrink transition but not Fade transition.

Exact steps for others to reproduce the error

Open attached file
Run animation
Note: It seems to be related to the background image.
flickeringBuild.blend

**System Information** Operating system: MacOS Catalina 10.15.4 iMac Retina 5K, late 2017 Graphics card: Radeon Pro 580 8GB **Blender Version** Broken: (2.83 beta) Worked: (2.82a) **Short description of error** A grease pencil object with a build modifier flickers in opacity in some strokes of a multi-stroke object. It occurs in the Sequential mode with Grow or Shrink transition but not Fade transition. **Exact steps for others to reproduce the error** - Open attached file - Run animation Note: It seems to be related to the background image. [flickeringBuild.blend](https://archive.blender.org/developer/F8553321/flickeringBuild.blend)

John Grigni commented

2020-05-19 17:43:00 +02:00

Added subscriber: @JohnGrigni-4

Germano Cavalcante commented

2020-05-20 15:48:59 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-05-20 15:48:59 +02:00

Could you provide a simple file showing the problem?

John Grigni commented

2020-05-20 23:08:05 +02:00

Actually, I think the culprit is that I had a background image in the camera view. When I disabled it, the flicker disappeared. It also didn't show in the render. Not sure what's going on, but here is the file. The flicker occurs in frames 41, 50, 76, and 88. It also isn't specific strokes, it looks like there is an invisible rectangle that occurs only on the right hand side of the image. flickeringBuild.blend

Actually, I think the culprit is that I had a background image in the camera view. When I disabled it, the flicker disappeared. It also didn't show in the render. Not sure what's going on, but here is the file. The flicker occurs in frames 41, 50, 76, and 88. It also isn't specific strokes, it looks like there is an invisible rectangle that occurs only on the right hand side of the image. [flickeringBuild.blend](https://archive.blender.org/developer/F8545445/flickeringBuild.blend)

Germano Cavalcante commented

2020-05-21 23:04:15 +02:00

Here is working normally with either the latest stable or current development versions of Blender:

Please try the latest daily build: https://builder.blender.org/download/

Here is working normally with either the latest stable or current development versions of Blender: ![gp_ok.gif](https://archive.blender.org/developer/F8546854/gp_ok.gif) Please try the latest daily build: https://builder.blender.org/download/

John Grigni commented

2020-05-22 16:12:11 +02:00

I notice you turned off the background image in the camera view. As I mentioned, when you disable the background image, the flicker disappears. I'll try the latest build just in case.

Germano Cavalcante commented

2020-05-25 16:56:52 +02:00

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

Germano Cavalcante commented

2020-05-25 16:56:52 +02:00

I just opened the file and slid the frames.
It appears to be a MacOS-specific bug.

I just opened the file and slid the frames. It appears to be a MacOS-specific bug.

Antonio Vazquez commented

2020-05-25 17:21:44 +02:00

Added subscriber: @antoniov

Antonio Vazquez commented

2020-05-25 17:21:44 +02:00

No problem here in Windows 10 with NVIDIA RTX2080 TI card.

John Grigni commented

2020-05-25 18:13:18 +02:00

I just realized i never packed the background image into the file, my apologies{F8553321}

I just realized i never packed the background image into the file, my apologies{[F8553321](https://archive.blender.org/developer/F8553321/flickeringBuild.blend)}

Germano Cavalcante commented

2020-05-25 19:36:15 +02:00

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

Germano Cavalcante commented

2020-05-25 19:37:05 +02:00

In the new file I can reproduce the problem.
I updated the description.

In the new file I can reproduce the problem. I updated the description.

Antonio Vazquez commented

2020-05-26 12:23:47 +02:00

Added subscriber: @fclem

Antonio Vazquez commented

2020-05-26 12:23:47 +02:00

I can reproduce too. It's clear is a problem with the background image.

IIRC there was already a bug like this open and set as know issue. Maybe @fclem has the answer.

I can reproduce too. It's clear is a problem with the background image. IIRC there was already a bug like this open and set as know issue. Maybe @fclem has the answer. ![image.png](https://archive.blender.org/developer/F8555390/image.png)

Antonio Vazquez commented

2020-05-26 12:25:34 +02:00

I have tested, and using a plane with the image (just use Image as Plane add-on and scale image) works perfect.

Flickering_Image_as_Plane.blend

I have tested, and using a plane with the image (just use Image as Plane add-on and scale image) works perfect. ![image.png](https://archive.blender.org/developer/F8555399/image.png) [Flickering_Image_as_Plane.blend](https://archive.blender.org/developer/F8555401/Flickering_Image_as_Plane.blend)

Antonio Vazquez changed title from ~~Build modifier on Grease Pencil causes opacity flickering~~ to GPencil: Flickering when use Background or Camera image

2020-05-26 12:27:49 +02:00

Alastair James commented

2020-05-30 13:54:09 +02:00

Added subscriber: @Alastair

Alastair James commented

2020-05-30 13:54:09 +02:00

With all else the same, lowering the opacity of the Grease Pencil layer which contains the strokes ('Lines' in this case) to below 1.0 also stops the flickering.

With all else the same, lowering the opacity of the Grease Pencil layer which contains the strokes ('Lines' in this case) to below 1.0 also stops the flickering. ![GreasePencil_Flickering_Opacity.PNG](https://archive.blender.org/developer/F8565339/GreasePencil_Flickering_Opacity.PNG)

Clément Foucault commented

2020-07-02 02:12:26 +02:00

This is due to the bounding box of the GPencil object being incorrect for the buggy frames.
The call to BKE_object_boundbox_get inside gpencil_object_cache_add is returning a Unit boundbox incorrectly.

I'll leave it up to @antoniov since it is not a drawing issue.

This is due to the bounding box of the GPencil object being incorrect for the buggy frames. The call to `BKE_object_boundbox_get` inside `gpencil_object_cache_add` is returning a Unit boundbox incorrectly. I'll leave it up to @antoniov since it is not a drawing issue.

Antonio Vazquez self-assigned this 2020-07-02 09:02:54 +02:00

blender-admin commented

2020-07-02 09:29:30 +02:00

This issue was referenced by 22197d7f8a

This issue was referenced by 22197d7f8a26fb1284435f554fbc8bb4a1735f16

Antonio Vazquez commented

2020-07-02 09:30:08 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Antonio Vazquez closed this issue

2020-07-02 09:30:08 +02:00

Antonio Vazquez commented

2020-07-02 09:31:33 +02:00

Fixed, Thanks @fclem for finding the root cause.

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GPencil: Flickering when use Background or Camera image #76886