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RNA_path_from_ID_to_property fails for pointcaches [thus ALT+click does as well...]
Closed, ResolvedPublicKNOWN ISSUE


I am a blender novice but cannot find out about this problem.
I am sorry if the problem is simply my lack of understanding and hope it does not take too much of your time to verify this issue.

System Information
Operating system: Windows 10 Pro 64-bit
Graphics card: 4095MB NVIDIA GeForce GTX 1080 (NVIDIA)

Blender Version
blender-2.80.0-git.0264d8390fa2-windows64 ( + all previous blender 2.8 tested to date)

Short description of error
A plane has cloth physics enabled.
end time in the (cloth physics) cache is changed to say 1000
Several duplicates of this are made.
Duplicates resort to 250 end time.
Cannot copy end time to selected duplicates either.
Only way to change end time for all duplicates is to do it one at a time manually.

Exact steps for others to reproduce the error
create a plane which is pinned at top so that it drops in the z direction
add physics cloth to this plane.
(I also enabled object (not self) collision but I don't think this is important).
Change the cache end time for the cloth to 1000
Duplicate the cloth (plane) several times
Then try to make the duplicates have a 1000 end time in the cache.

Event Timeline

Philipp Oeser (lichtwerk) lowered the priority of this task from 90 to 30.May 14 2019, 11:31 AM

Just checking if I get this right:

  • How are you trying to achieve this?
  • Is this about selecting multiple objects and Alt+clicking cache end time to enter a new value?

I was initially simply trying to duplicate a cloth object with the cache end changed.
I had expected the updated value to be in the duplicated object, but it was the original 250.

I also tried to change the simulation end time before duplicating the object but that made no difference.

I have tried selecting one cloth and then the rest (because they are all in a single group).
I did not try alt clicking the end time, just altering it.
However, I have tried alt clicking the end time and altering it now and it still does not update the selected objects.

The balance of probabilities says that this is my mistake and I was waiting for updates to version 2.8.
However, I thought I should at least mention it with the release date approaching.
I am really sorry if I end up causing work for you for nothing.

Basically, I can’t change multiple cloth cache end times other than by changing each one, one at a time.

Philipp Oeser (lichtwerk) raised the priority of this task from 30 to Normal.

Can confirm Alt+clicking [easiest] doesnt work in this case.
This is because the path to the property on the pointcache cannot be resolved (RNA_path_from_ID_to_property fails).

[this should resolve to something like ob.modifiers['Cloth'].point_cache.frame_end but it doesnt...]

This is true for a couple of properties all around blender and can possibly be fixed [could be a bit tricky since pointcache is used in multiple places], will have a look...

As a workaround, you could just fire a small script:

import bpy

frame_end = 666

for ob in bpy.context.selected_objects:
    for mod_cloth in [mod for mod in ob.modifiers if mod.type == "CLOTH"]:
        mod_cloth.point_cache.frame_end = frame_end

I'll keep this report open for now and retitle so it is more obvious why this fails...

Philipp Oeser (lichtwerk) renamed this task from can't copy or duplicate cloth cache start or end to RNA_path_from_ID_to_property fails for pointcaches [thus ALT+click does as well...].May 14 2019, 2:57 PM
Richard Antalik (ISS) changed the subtype of this task from "Report" to "Known Issue".