Copy Global Transform: Two bugs when copying transforms with two ChildOf constraints #97161

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Henrique Corrêa · 2022-04-08T05:10:54+02:00

Henrique Corrêa commented

2022-04-08 05:10:54 +02:00

System Information
Operating system: Windows 10
Graphics card: GTX 1050 Ti

Blender Version
Broken: 3.2.0 alpha, 87a3bf3356, master, 2022-04-07 23:10
Worked: none

Addon Version
Copy Global Transform: 2.0

Short description of error
I found two bugs/incorrect behaviors when copying transforms of an object with two ChildOf constraints (when the parents swap influences).

Exact steps for others to reproduce the error
First of all, I cannot thank you enough for developing this addon. it has saved me a lot of time in just a few days of using it.

So, I was actually trying to reproduce one of the bugs (where nothing happens) and found the second case where the transform is incorrect.

Case 1 (nothing happens):
0. open provided .blend file

select the cube
copy transforms from frame 59
paste transforms on frame 60

Case 2 (incorrect transform):
0. open provided .blend file

select the cube
copy transforms from frame 60
paste transforms on frame 59

Here's a video demonstrating the issue:
2022-04-07 23-56-36.mp4

And here's the .blend file (created in 3.0.1):
multi-parenting copy transform bugs.blend

It would be absolutely vital for my workflow if this got fixed since this type of transform copying (between ChildOf swaps, after tweaking a parent keyframe) happens almost all the time.

Thanks!

CC @dr.sybren

**System Information** Operating system: Windows 10 Graphics card: GTX 1050 Ti **Blender Version** Broken: 3.2.0 alpha, 87a3bf33564b, master, 2022-04-07 23:10 Worked: none **Addon Version** Copy Global Transform: 2.0 **Short description of error** I found two bugs/incorrect behaviors when copying transforms of an object with two ChildOf constraints (when the parents swap influences). **Exact steps for others to reproduce the error** First of all, I cannot thank you enough for developing this addon. it has saved me a **lot** of time in just a few days of using it. So, I was actually trying to reproduce one of the bugs (where nothing happens) and found the second case where the transform is incorrect. Case 1 (nothing happens): 0. open provided .blend file 1. select the cube 2. copy transforms from frame 59 3. paste transforms on frame 60 Case 2 (incorrect transform): 0. open provided .blend file 1. select the cube 2. copy transforms from frame 60 3. paste transforms on frame 59 Here's a video demonstrating the issue: [2022-04-07 23-56-36.mp4](https://archive.blender.org/developer/F12982614/2022-04-07_23-56-36.mp4) And here's the .blend file (created in 3.0.1): [multi-parenting copy transform bugs.blend](https://archive.blender.org/developer/F12982612/multi-parenting_copy_transform_bugs.blend) It would be absolutely vital for my workflow if this got fixed since this type of transform copying (between ChildOf swaps, after tweaking a parent keyframe) happens almost all the time. Thanks! CC @dr.sybren

Henrique Corrêa commented

2022-04-08 05:10:54 +02:00

Added subscribers: @dr.sybren, @HeCorr

Philipp Oeser commented

2022-04-08 11:28:41 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-04-08 11:28:41 +02:00

This is probably not related to the Addon (since this is just setting the matrix on the object/bone).
But this seems related to the inverse correction of the constraints (see below)

A little bit confused though (excuse me, not an animator here so please bare with me):
since this is fully constrained

it would hop back to fully constrained on framechange
how are you intending to use it, how would this end up on the "second" parent then?

I am assuming you are trying to keep the animation on the "second" parent, but want the object to match on the "handover"?

One way to achieve this is setting the inverse correction of the "second" constraint on the last frame the first constraint has full influence (this at least covers the Case 1 from your report)?
Of course, you would then have to tweak the end of the animation of the "second" parent...
#97161.webm

Does this help?

@dr.sybren : think there is a way to handle pasting with constraints (in regards to the Inverse) better?

This is probably not related to the Addon (since this is just setting the matrix on the object/bone). But this seems related to the inverse correction of the constraints (see below) A little bit confused though (excuse me, not an animator here so please bare with me): since this is fully constrained - it would hop back to fully constrained on framechange - how are you intending to use it, how would this end up on the "second" parent then? I am *assuming* you are trying to keep the animation on the "second" parent, but want the object to match on the "handover"? One way to achieve this is setting the inverse correction of the "second" constraint on the last frame the first constraint has full influence (this at least covers the `Case 1` from your report)? Of course, you would then have to tweak the end of the animation of the "second" parent... [#97161.webm](https://archive.blender.org/developer/F12983567/T97161.webm) Does this help? @dr.sybren : think there is a way to handle pasting with constraints (in regards to the `Inverse`) better?

Henrique Corrêa commented

2022-04-09 00:19:38 +02:00

@lichtwerk that actually does work! I just needed to copy transforms from frame 79 to 80 afterwards (which works because a single constraint is being switched, not two at once).

And I even tried "grabbing" the cube with the first bone again and tweaking it and it still worked without breaking the rest of the animation. Awesome!

2022-04-08 18-48-45.mp4

As I'm writing this I'm actually realizing I could have just been using the Set Inverse this whole time instead of Copy Global Transform for this kind of parent adjustment. Now I know. :)

I haven't considered trying the ChildOf buttons before because honestly I've never understood what they do exactly so I just never touch them (I use the Dynamic Parent addon so I don't have to).

I'll consider that as a workaround though as I still think Copy Global Transform should handle this automatically (if possible, of course).

Thank you very much!

@lichtwerk that actually does work! I just needed to copy transforms from frame 79 to 80 afterwards (which works because a single constraint is being switched, not two at once). And I even tried "grabbing" the cube with the first bone again and tweaking it and it still worked without breaking the rest of the animation. Awesome! [2022-04-08 18-48-45.mp4](https://archive.blender.org/developer/F12984568/2022-04-08_18-48-45.mp4) As I'm writing this I'm actually realizing I could have just been using the Set Inverse this whole time instead of Copy Global Transform for this kind of parent adjustment. Now I know. :) I haven't considered trying the ChildOf buttons before because honestly I've never understood what they do exactly so I just never touch them (I use the Dynamic Parent addon so I don't have to). I'll consider that as a workaround though as I still think Copy Global Transform should handle this automatically (if possible, of course). Thank you very much!

Sybren A. Stüvel commented

2022-04-11 12:44:43 +02:00

Changed status from 'Needs Triage' to: 'Archived'

Sybren A. Stüvel closed this issue

2022-04-11 12:44:43 +02:00

Sybren A. Stüvel commented

2022-04-11 12:44:43 +02:00

I want to keep Copy Global Transform as simple as possible, and avoid the situation where it has to guess and modify more than just the object/bone's transform.

Of course if someone wants to add an operator to the addon, call it "ChildOf Handover" or something, and only show it when there are two ChildOf constraints on the object/bone, that's fine. Personally I don't have the time to work on that right now, though.

Also, the Child Of constraint is notoriously hard to work with, and one wrong button click will ruin the resulting animation in a way that's very hard to recover from. If there's any effort done to improve working with the constraint, I feel that it would be much better to spend that effort on improving the constraint UI/operation itself, rather than writing more addon code to circumvent its issues.

I want to keep Copy Global Transform as simple as possible, and avoid the situation where it has to guess and modify more than just the object/bone's transform. Of course if someone wants to add an operator to the addon, call it "ChildOf Handover" or something, and only show it when there are two ChildOf constraints on the object/bone, that's fine. Personally I don't have the time to work on that right now, though. Also, the Child Of constraint is notoriously hard to work with, and one wrong button click will ruin the resulting animation in a way that's very hard to recover from. If there's any effort done to improve working with the constraint, I feel that it would be much better to spend that effort on improving the constraint UI/operation itself, rather than writing more addon code to circumvent its issues.

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Copy Global Transform: Two bugs when copying transforms with two ChildOf constraints #97161