Drivers set to Active Camera's Pass Index only updating on Grease Pencil objects #112212

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Matthew Gafford · 2023-09-11T02:46:28+02:00

Matthew Gafford commented

2023-09-11 02:46:28 +02:00

System Information
Operating system: Win 11 Home
Graphics card: RTX4090

Blender Version
Broken: 3.6.1
Worked: N/A

Short description of error

Drivers set to the active camera's pass index only update on Grease Pencil objects, and not meshes, bezier curves, etc.

Video Explanation
https://www.youtube.com/watch?v=l1VAbHzugno

Exact steps for others to reproduce the error

Download .blend
DriverSetToActiveCameraNotUpdating.blend

Make two cameras, give one a pass index of 1, and the other a pass index of 2
Put two markers on the timeline and set each marker to a different camera
Create a Grease Pencil object and a mesh object, then set both of their Show in Viewport/Render icons to a driver with the following expression:
bpy.context.scene.camera.pass_index != 1
Drag the timeline back and forth to see that only the Grease Pencil object updates properly.

**System Information** Operating system: Win 11 Home Graphics card: RTX4090 **Blender Version** Broken: 3.6.1 Worked: N/A **Short description of error** Drivers set to the active camera's pass index only update on Grease Pencil objects, and not meshes, bezier curves, etc. Video Explanation https://www.youtube.com/watch?v=l1VAbHzugno **Exact steps for others to reproduce the error** Download .blend [DriverSetToActiveCameraNotUpdating.blend](/attachments/826ea4d0-674d-48b5-82eb-ee803196511a) 1. Make two cameras, give one a pass index of 1, and the other a pass index of 2 2. Put two markers on the timeline and set each marker to a different camera 3. Create a Grease Pencil object and a mesh object, then set both of their Show in Viewport/Render icons to a driver with the following expression: bpy.context.scene.camera.pass_index != 1 4. Drag the timeline back and forth to see that only the Grease Pencil object updates properly.

DriverSetToActiveCameraNotUpdating.blend

1020 KiB

Matthew Gafford added the

labels 2023-09-11 02:46:29 +02:00

YimingWu commented

2023-09-11 04:32:41 +02:00

Hi! you should be able to see a warning message when you add driver via this kind of path bpy.context.scene.camera.pass_index like this:

The reason is that the expression is evaluated in python, blender will have no idea on what data this expression depends on, thus this expression could be evaluated before scene camera switch. To get it to work, you could specify scene camera as a driver variable like this, this way blender will know to evaluate scene camera before objects, then you can get correct result:

Please verify if this does solve the issue. Thanks for reporting!

Hi! you should be able to see a warning message when you add driver via this kind of path `bpy.context.scene.camera.pass_index` like this: ![图片](/attachments/fdc79c8b-2185-4ede-98b8-8b6804b27abe) The reason is that the expression is evaluated in python, blender will have no idea on what data this expression depends on, thus this expression could be evaluated before scene camera switch. To get it to work, you could specify scene camera as a driver variable like this, this way blender will know to evaluate scene camera before objects, then you can get correct result: ![图片](/attachments/0cb0d565-feb0-4f5e-9359-ddbd18c1b135) Please verify if this does solve the issue. Thanks for reporting!

图片.png

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图片.png

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YimingWu added

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labels 2023-09-11 04:34:24 +02:00

Matthew Gafford commented

2023-09-11 05:06:28 +02:00

Thank you, that worked perfectly. I just thought it was strange that it worked for GP objects but not anything else. Hope I didn't waste anyone's time!

👍 1

Matthew Gafford closed this issue

2023-09-11 05:06:31 +02:00

Blender Bot added

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labels 2023-09-11 05:06:32 +02:00

YimingWu commented

2023-09-11 05:24:35 +02:00

Glad it solved :)

Matthew Gafford commented

2024-04-30 03:40:48 +02:00

Glad it solved :)

Just tried this again in 4.1.1 RC, and I'm having the same problem again; only Grease Pencil objects work with your solution.

For anyone else having this problem, I fixed it by moving the ".pass_index" property from var down to camera:

> Glad it solved :) Just tried this again in 4.1.1 RC, and I'm having the same problem again; only Grease Pencil objects work with your solution. For anyone else having this problem, I fixed it by moving the ".pass_index" property from var down to camera: ![image](/attachments/d1c7390c-923b-4454-9447-b2e6ba12ff23)

image.png

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Drivers set to Active Camera's Pass Index only updating on Grease Pencil objects #112212