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Particle system: late update of object`s tracking axis after «object`s rotation» switching.
Confirmed, NormalPublicKNOWN ISSUE

Description

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.59

Blender Version
Broken: version: 2.83 (sub 13), branch: master, commit date: 2020-04-16 15:38, hash: rB8cb10c124efe
Worked: Apparently never (2.79 has the same problem)

Short description of error
After switching on/off object`s rotation for particles, their rotation updates wrong and I need to switch something at initial object to update rotation of particles.

Exact steps for others to reproduce the error

  • Make particle system, that emits object.
  • Switch object`s tracking axis to +Z (relations)
  • Switch Object`s rotation in the particle system render tab.
  • Rotation is wrong and not changing until object`s transform not updated.

or

  • Open attached file
  • Move the "Cone" object to update the particles
  • In the Cube particle settings, enable and disable Object Rotation

Event Timeline

Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Confirmed.Apr 23 2020, 3:10 PM
Germano Cavalcante (mano-wii) updated the task description. (Show Details)
Germano Cavalcante (mano-wii) changed the subtype of this task from "Report" to "Bug".
Richard Antalik (ISS) closed this task as Archived.Apr 23 2020, 3:13 PM
Richard Antalik (ISS) claimed this task.

Rotation is wrong and not changing until object`s transform not updated.

I don't really think rotation is wrong at that moment. Issue seems to be that when you transform instanced object, particle system will stay in invalid state.

Particle system is at the end of life stage and will be replaced. So even if this is wrong behavior, it won't be considered a bug.

If you want to align object with "hair direction", you should use enable rotation property https://docs.blender.org/manual/en/dev/physics/particles/emitter/rotation.html#rotation

@IIS
I know about Everything nodes/Functional nodes, but when it will be able in master? A year? Two? More?

A don`t need hairs for it. I would like proper update to +Z. Okay, it is not critical at all. But still can confuse new users and turn them out of blender.
Perhaps fixing it is waste of time and I don`t want it.
But it is still rotation to wrong axis after changing particle system.

So you can mark it as a bug with low priority for example. FTGJ and to be sure, that such behavior will not migrate to new system unchanged.

Richard Antalik (ISS) reopened this task as Confirmed.Apr 23 2020, 5:00 PM
Richard Antalik (ISS) changed the subtype of this task from "Bug" to "Known Issue".

@IIS
I know about Everything nodes/Functional nodes, but when it will be able in master? A year? Two? More?

Nobody knows exactly, but it is listed in 2020 projects https://code.blender.org/2020/01/2020-blender-big-projects/
Some of them are already implemented in master

So you can mark it as a bug with low priority for example. FTGJ and to be sure, that such behavior will not migrate to new system unchanged.

Ok I will do this. Though as I said particle system is EOL so this will have to be "known issue" (like T68436).


One more connected problem. Such behavior force me to refresh manually rotation. Otherwise, initial normal rotation will be broken.