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Driver read but not write values to linked objects
Open, Needs Triage by DeveloperPublic

Description

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.15

Blender Version
Broken: version: 2.81 (sub 11), branch: master, commit date: 2019-09-16 21:02, hash: rB76650402f300
Worked: (optional)

Short description of error
Setting a value to linked objects works with

bpy.data.objects['myCube'].pass_index = 2

or

bpy.data.objects['myCube'].pass_index = bpy.data.objects['Controller']['my_new_index']

but not when accessed via driver

Exact steps for others to reproduce the error
Ok, I dont know if this is a limitation , a bug, a missunderstandment from me or a wrong setup as seen in the Image
but
my driver reads the correct value from the linked object "myCube" and I can set the value via Python

I created myCube in a second file
--> my cube has different colors based on object Index
I create a mainfile and link myCube in
--> to test the linked Connection I change myCube.pass_index via Python
--> colors of myCube changes accordingly
I create a Driver with single property set to myCube.pass_index
value is shown as set in myCube file
I create second var that catches the value of a custom property called my_new_index from "Controller" object
I change "my_new_index" and the Driver value changes accordingly but
--> Colors dont change - so pass index is not changed
--> to test the linked Connection I change myCube.pass_index via Python
--> colors of myCube changes accordingly

it seems that values of linked objects can be Change with Python and can be read by a Driver but not written

[Based on the default startup or an attached .blend file (as simple as possible)]
here are the files - myCube has to be in assets Folder reletiv to Main.blend


Details

Type
Bug

Event Timeline

Additional:


The Driver connection is lost after closing and reopening the Scene (Main.blend)