Animation driver takes data from previous frame #72899

New Issue

Piotr Załóg · 2020-01-04T15:31:40+01:00

Piotr Załóg commented

2020-01-04 15:31:40 +01:00

Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48

Broken: version:
2.81 (sub 16), branch: master, commit date: 2019-12-04 11:32, hash: f1aa4d18d4, type: Release
2.82 (sub 6), branch: master, commit date: 2020-01-03 10:02, hash: 9b74e648c5

Animation driver takes data from previous frame instead current. For example on scene is square. X-scale is animated to shrink from 1 to 0. Y-scale has simple driver, to copy animation form x-scale. When play animation or render movie, x- and y-scale aren't the same. Square become rectangle, because y-scale is taken for previous frame.

bug_driver_data_from_previous_frame_01.blend

Download .blend file.
Start pressing right arrow on keyboard and observe x- and y-scale. They aren't the same. Y-scale become x-scale from previous frame.
Use mouse and timeline to change frame. Driver will copy value (x-axis) from current frame.
Render animation - problem appears not only in viewport.

[Sometimes during rendering animation driver doesn't work at all and property isn't animated, but I can't repeat this issue.]

Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48 Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-12-04 11:32, hash: f1aa4d18d49d, type: Release 2.82 (sub 6), branch: master, commit date: 2020-01-03 10:02, hash: `9b74e648c5` Animation driver takes data from previous frame instead current. For example on scene is square. X-scale is animated to shrink from 1 to 0. Y-scale has simple driver, to copy animation form x-scale. When play animation or render movie, x- and y-scale aren't the same. Square become rectangle, because y-scale is taken for previous frame. [bug_driver_data_from_previous_frame_01.blend](https://archive.blender.org/developer/F8259669/bug_driver_data_from_previous_frame_01.blend) - Download .blend file. - Start pressing right arrow on keyboard and observe x- and y-scale. They aren't the same. Y-scale become x-scale from previous frame. - Use mouse and timeline to change frame. Driver will copy value (x-axis) from current frame. - Render animation - problem appears not only in viewport. # [Sometimes during rendering animation driver doesn't work at all and property isn't animated, but I can't repeat this issue.]

Piotr Załóg commented

2020-01-04 15:31:40 +01:00

Added subscriber: @piotr-14

Philipp Oeser commented

2020-01-06 11:00:23 +01:00

Added subscribers: @Sergey, @dr.sybren, @lichtwerk

Philipp Oeser commented

2020-01-06 11:00:23 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2020-01-06 11:00:23 +01:00

I think this is a dependency cycle behind the scenes (even though this is not reported properly?)

The driver in bug_driver_data_from_previous_frame_01.blend is set up as Driver variable type Transform Channel
If I do the same thing with a Driver variable type Single Property I get a dependency cycle reported:

bug_driver_data_from_previous_frame_01_single_property.blend

Dependency cycle detected:
  OBSquare/Transform Component/TRANSFORM_INIT() depends on
  OBSquare/Parameters Component/DRIVER(scale) via 'Driver -> Driven Property'
  OBSquare/Transform Component/TRANSFORM_FINAL() via 'RNA Target -> Driver'
  OBSquare/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform'
  OBSquare/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBSquare/Transform Component/TRANSFORM_LOCAL() via 'Eval'
  OBSquare/Transform Component/TRANSFORM_INIT() via 'Transform Init'
Detected 1 dependency cycles

So, as a workaround, it might be better to set this up via a dummy object [which has the action and then drives both channels of the square], like so:
bug_driver_data_from_previous_frame_01_single_property_corrected.blend

And this might not be a bug in the end, however, @Sergey, @dr.sybren: shouldnt the driver set up via Transform Channel report a dependency cycle (just like doing it via Single Property does?)

I think this is a dependency cycle behind the scenes (even though this is not reported properly?) The driver in `bug_driver_data_from_previous_frame_01.blend` is set up as Driver variable type `Transform Channel` If I do the same thing with a Driver variable type `Single Property` I get a dependency cycle reported: [bug_driver_data_from_previous_frame_01_single_property.blend](https://archive.blender.org/developer/F8261992/bug_driver_data_from_previous_frame_01_single_property.blend) ``` Dependency cycle detected: OBSquare/Transform Component/TRANSFORM_INIT() depends on OBSquare/Parameters Component/DRIVER(scale) via 'Driver -> Driven Property' OBSquare/Transform Component/TRANSFORM_FINAL() via 'RNA Target -> Driver' OBSquare/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform' OBSquare/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBSquare/Transform Component/TRANSFORM_LOCAL() via 'Eval' OBSquare/Transform Component/TRANSFORM_INIT() via 'Transform Init' Detected 1 dependency cycles ``` So, as a workaround, it might be better to set this up via a dummy object [which has the action and then drives both channels of the square], like so: [bug_driver_data_from_previous_frame_01_single_property_corrected.blend](https://archive.blender.org/developer/F8261994/bug_driver_data_from_previous_frame_01_single_property_corrected.blend) And this might not be a bug in the end, however, @Sergey, @dr.sybren: shouldnt the driver set up via `Transform Channel` report a dependency cycle (just like doing it via `Single Property` does?)

Sergey Sharybin commented

2020-01-06 11:17:20 +01:00

The dependency cycle is not reported on purpose actually: while animated property can not currently control driver, rigs were using a lot of non-animated properties properties as a driver variable. For example, using non-animated X-value of a transform is fine to drive Y of scale.

This behavior is used a lot by rigs here and in other studios, and printing dependency cycle would spam terminal to a degree that you wouldn't be able to find real issues.

Think real solution would be to support such setups, but this is already reported as #64793.

The dependency cycle is not reported on purpose actually: while animated property can not currently control driver, rigs were using a lot of non-animated properties properties as a driver variable. For example, using non-animated X-value of a transform is fine to drive Y of scale. This behavior is used a lot by rigs here and in other studios, and printing dependency cycle would spam terminal to a degree that you wouldn't be able to find real issues. Think real solution would be to support such setups, but this is already reported as #64793.

Sergey Sharybin commented

2020-01-06 11:17:36 +01:00

Closed as duplicate of #64793

Sergey Sharybin closed this issue

2020-01-06 11:17:36 +01:00

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Animation driver takes data from previous frame #72899

[Sometimes during rendering animation driver doesn't work at all and property isn't animated, but I can't repeat this issue.]