NLA animated time strip with a driver displays a wrong frame when going back in time #86107

New Issue

Emilien Colombier · 2021-02-28T23:34:13+01:00

Emilien Colombier commented

2021-02-28 23:34:13 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.79

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-02-25 05:34, hash: 0e1c6a29cb

version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: 02948a2cab
Worked: never

Short description of error
When using a driver on the "animated time strip" property of an NLA track, the animation is offseted when going backward in time, with the arrow keys. This makes the animation review process very hard.

Exact steps for others to reproduce the error
(see video attached)

#86107.blend

animate the default cube (example : revolution on Z axis, from frame 1 to 250
create an empty, add a custom property, set the max to 250
keyframe the custom property as : frame 1 value 1.00 ; frame 250 value 250.00.
tweak the animation curve of the custom property to get a nice S shape
copy the custom property as a new driver
go to the NLA, push down the cube action, go to it's strip option and check "animated time strips"
paste the driver on the "animated time strips" value
now if you go forward and backward with the arrowkeys, you'll see that the animation is doing some weird frame offset

bugreport_wrongframe.mp4

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.79 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-02-25 05:34, hash: `0e1c6a29cb` + version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: `02948a2cab` Worked: never **Short description of error** When using a driver on the "animated time strip" property of an NLA track, the animation is offseted when going backward in time, with the arrow keys. This makes the animation review process very hard. **Exact steps for others to reproduce the error** (see video attached) [#86107.blend](https://archive.blender.org/developer/F9855913/T86107.blend) animate the default cube (example : revolution on Z axis, from frame 1 to 250 create an empty, add a custom property, set the max to 250 keyframe the custom property as : frame 1 value 1.00 ; frame 250 value 250.00. tweak the animation curve of the custom property to get a nice S shape copy the custom property as a new driver go to the NLA, push down the cube action, go to it's strip option and check "animated time strips" paste the driver on the "animated time strips" value now if you go forward and backward with the arrowkeys, you'll see that the animation is doing some weird frame offset [bugreport_wrongframe.mp4](https://archive.blender.org/developer/F9853764/bugreport_wrongframe.mp4)

Emilien Colombier commented

2021-02-28 23:34:13 +01:00

Added subscriber: @Peine_Perdue

Philipp Oeser commented

2021-03-01 10:54:02 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-03-01 10:54:02 +01:00

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

Philipp Oeser commented

2021-03-01 10:54:02 +01:00

I can confirm the behavior.

However, as stated in #86109 (driver on an NLA animated time strip isn't purple and cannot be removed), I think this is due to the fact that this is not supposed to be driven in the first place:

In #86109#1121015, @lichtwerk wrote:
NLA control curves seem to get special handling in BKE_fcurve_find_by_rna_context_ui

See the following two comments:
/* Special case for NLA Control Curves... */
    /* Set the special flag, since it cannot be a normal action/driver
     * if we've been told to start looking here...
     */
If it is not supposed to be supported, I guess it would be good to prevent adding drivers in the first place.

related: b617dec065

Will confirm for now.

#86107.blend

I can confirm the behavior. However, as stated in #86109 (driver on an NLA animated time strip isn't purple and cannot be removed), I think this is due to the fact that this is not supposed to be driven in the first place: > In #86109#1121015, @lichtwerk wrote: > NLA control curves seem to get special handling in `BKE_fcurve_find_by_rna_context_ui` > > See the following two comments: > > > ``` > /* Special case for NLA Control Curves... */ > ``` > > ``` > /* Set the special flag, since it cannot be a normal action/driver > * if we've been told to start looking here... > */ > ``` > If it is not supposed to be supported, I guess it would be good to prevent adding drivers in the first place. > > related: b617dec065 Will confirm for now. [#86107.blend](https://archive.blender.org/developer/F9855913/T86107.blend)

Emilien Colombier commented

2021-03-01 11:07:46 +01:00

If it is not supposed to be supported, I guess it would be good to prevent adding drivers in the first place.

Using a driver on this value is essantial when you want the same time remapping on multiple object on your scene. Removing it would be a huge error in my opinion

> If it is not supposed to be supported, I guess it would be good to prevent adding drivers in the first place. Using a driver on this value is essantial when you want the same time remapping on multiple object on your scene. Removing it would be a huge error in my opinion

Wayde Moss commented

2021-03-02 01:58:50 +01:00

Added subscriber: @wbmoss_dev

Philipp Oeser removed the

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NLA animated time strip with a driver displays a wrong frame when going back in time #86107