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Value's driver not working with expression based on that same value.
Closed, InvalidPublic

Description

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 960M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 388.57

Blender Version
Broken: version: 2.80 (sub 57), branch: master, commit date: 2019-04-16 20:13, hash: rB5d8030b8f3cf
Worked: (optional)

Short description of error
Driver expression based on the property the driver is handling is updated only when the expression itself is updated or the "Update Dependencies" button is clicked or when the blend file is loaded.

Exact steps for others to reproduce the error

  1. Add a driver;
  2. Add a variable to the driver;
  3. Set the variable value to the property the driver handles;
  4. Base the expression on that variable.

Details

Type
Bug

Event Timeline

Though I understand, what you hope, but these kind Expression, location Z = Location Z+ 1.00 (circular driver) never work .
I do not think it can be achived.

You may need to set value for "Delta transform" to get what you need, I think. (just input value for delta transform property )

Sebastian Parborg (zeddb) claimed this task.

Right, we do not support circular drivers like these.

Right, we do not support circular drivers like these.

But circular drivers are supported in Blender 2.79.

Yes, things like this might work in 2.79. But there were not officially supported.

Now when we have a better evaluator in place, we can't support this.

In your case the evaluation would never stop and the location would quickly approach infinity.

I actually requested to achive these type driver in right-click select before. (more complex case)

To achive it, each properties need to keep "User manipulate value" but show final value of the driver function as property.

Actually I know one aprication which have such driver and property UI. then we can still change driven property value from UI without problem. and we can check "user manipulate value" from setting of the property.

But at least current blender can not change (not support) driven value from UI. If it worked for 2.7, it is not correct manner, it means blender 2.7 could not up-date driven value correctly when you input value. if it up-date correctly, it should cause circulation when slide value from UI.