Sequencer: Driver on any strip property does not invalidate its cache [prefetch frames] #82776

New Issue

System Information
Operating system: Darwin-18.6.0-x86_64-i386-64bit 64 Bits
Graphics card: Intel Iris OpenGL Engine Intel Inc. 4.1 INTEL-12.9.22

Blender Version
Broken: version: 2.83.9, branch: master, commit date: 2020-11-11 06:30, hash: 4abfc0bcd5
Worked: (newest version of Blender that worked as expected)

Short description of error
Sequencer: Driver on any strip property does not invalidate its cache [prefetch frames]
This can be any driver on any driven strip property:
Does not matter which property is the driving property (could be x Location of default cube as well)

Exact steps for others to reproduce the error

#82776.blend

Open file
driven strips opacity is driven by Cube 's X location
change Cube 's X location --> driven strips opacity value changes, but the cache is not invalidated

Original report:

Short description of error
Driver on wipe.effect_fader doesn't invalidate cache for driven wipe sequences. It's only invalidates the cache of the currently displayed wipe. This leads to display errors.

NB: The issue is the same for any other parameter (e.g angle, blur...)

Exact steps for others to reproduce the error

Open this file: Bug_Wipe_Driver.blend
There are two wipes, the first is the driver, the second one has the effect_fader value driven. Prefetch is enabled.
Move the effect_fader value of the driving wipe, its cache is reloaded, but not the cache of the driven one.

**System Information** Operating system: Darwin-18.6.0-x86_64-i386-64bit 64 Bits Graphics card: Intel Iris OpenGL Engine Intel Inc. 4.1 INTEL-12.9.22 **Blender Version** Broken: version: 2.83.9, branch: master, commit date: 2020-11-11 06:30, hash: `4abfc0bcd5` Worked: (newest version of Blender that worked as expected) **Short description of error** Sequencer: Driver on any strip property does not invalidate its cache [prefetch frames] This can be any driver on any driven strip property: Does not matter which property is the driving property (could be x Location of default cube as well) **Exact steps for others to reproduce the error** [#82776.blend](https://archive.blender.org/developer/F9326916/T82776.blend) - Open file - `driven` strips opacity is driven by Cube 's X location - change Cube 's X location --> driven strips opacity value changes, but the cache is not invalidated --- Original report: **Short description of error** Driver on `wipe.effect_fader` doesn't invalidate cache for driven wipe sequences. It's only invalidates the cache of the currently displayed wipe. This leads to display errors. NB: The issue is the same for any other parameter (e.g angle, blur...) **Exact steps for others to reproduce the error** - Open this file: [Bug_Wipe_Driver.blend](https://archive.blender.org/developer/F9309737/Bug_Wipe_Driver.blend) - There are two wipes, the first is the driver, the second one has the `effect_fader` value driven. Prefetch is enabled. - Move the `effect_fader` value of the driving wipe, its cache is reloaded, but not the cache of the driven one.

Added subscriber: @Miadim

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

Added subscriber: @lichtwerk

This can be any driver on any driven strip property:

#82776.blend

Does not matter which property is the driving property (could be x Location of default cube as well)

This can be any driver on any driven strip property: [#82776.blend](https://archive.blender.org/developer/F9316311/T82776.blend) Does not matter which property is the driving property (could be x Location of default cube as well)

Added subscriber: @dr.sybren

The example file has a dependency cycle, so it's not a situation that is supported at the moment:

Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles
Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles
Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles

@lichtwerk your file also has a dependency cycle:

Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles
Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles
Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles

The example file has a dependency cycle, so it's not a situation that is supported at the moment: ``` Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["Wipe"].effect_fader) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles ``` @lichtwerk your file also has a dependency cycle: ``` Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles ```

In #82776#1057865, @dr.sybren wrote:
@lichtwerk your file also has a dependency cycle:

Oops, but like I said

Does not matter which property is the driving property (could be x Location of default cube as well)

So here is one that doesnt have a dependency cycle (but still has the bug)
#82776.blend

> In #82776#1057865, @dr.sybren wrote: > @lichtwerk your file also has a dependency cycle: Oops, but like I said > Does not matter which property is the driving property (could be x Location of default cube as well) So here is one that doesnt have a dependency cycle (but still has the bug) [#82776.blend](https://archive.blender.org/developer/F9326916/T82776.blend)

If I get this right, this also means that you cannot drive a strip with another strip. ever. right?

Dependency cycle detected:
  SCScene/Sequencer Component/SEQUENCES_EVAL() depends on
  SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property'
  SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver'
Detected 1 dependency cycles

If I get this right, this also means that you cannot drive a strip with another strip. ever. right? ``` Dependency cycle detected: SCScene/Sequencer Component/SEQUENCES_EVAL() depends on SCScene/Parameters Component/DRIVER(sequence_editor.sequences_all["driven"].blend_alpha) via 'Driver -> Driven Property' SCScene/Sequencer Component/SEQUENCES_EVAL() via 'RNA Target -> Driver' Detected 1 dependency cycles ```

@dr.sybren I made this first example as a POC, but the issue remains the same with a custom FloatProperty driving a value. I don't think the circular dependency is the issue here.

Added subscriber: @Sergey

@Miadim a file that has an unsupported situation can't really be used as an example for a bug report. @lichtwerk's new file works fine.

In #82776#1057874, @lichtwerk wrote:
If I get this right, this also means that you cannot drive a strip with another strip. ever. right?

There are no separate dependency graph nodes for each sequencer strip. It's also not desirable to create those, unless they're absolutely necessary, to keep the size of the depsgraph in check. This is something that could be looked at, at some point.

About the actual issue at hand (update of driver input value doesn't cause invalidation of sequencer cache), I think this is simply a known limitation, rather than a bug. @Sergey what do you think?

@Miadim a file that has an unsupported situation can't really be used as an example for a bug report. @lichtwerk's new file works fine. > In #82776#1057874, @lichtwerk wrote: > If I get this right, this also means that you cannot drive a strip with another strip. ever. right? There are no separate dependency graph nodes for each sequencer strip. It's also not desirable to create those, unless they're absolutely necessary, to keep the size of the depsgraph in check. This is something that could be looked at, at some point. About the actual issue at hand (update of driver input value doesn't cause invalidation of sequencer cache), I think this is simply a known limitation, rather than a bug. @Sergey what do you think?

@dr.sybren I agree, I didn't notice this circular dependency when submitting, else I would have done it in another way. Sorry for that.

@dr.sybren I think there are two separate issues:

Issue #1: Dependency cycle caused by lack of granularity of strips. Solution which will keep the dependency graph size/complexity under control will be to treat such properties similar to ID property: for driven properties create corresponding node. This is more of an improvement than a bug.

Here is a quick demonstration of the idea (didn't have time to build it to scale or paint it though):

Issue #2: Lack of cache invalidation on driver changes. As Philipp mentioned, this happens in scenario without the dependency graph cycle as well. This is a bug. Although, can not give an immediate suggestion of a preferred fix for it at this time.

@dr.sybren I think there are two separate issues: Issue #1: Dependency cycle caused by lack of granularity of strips. Solution which will keep the dependency graph size/complexity under control will be to treat such properties similar to ID property: for driven properties create corresponding node. This is more of an improvement than a bug. Here is a quick demonstration of the idea (didn't have time to build it to scale or paint it though): ![PXL_20201120_101134465.jpg](https://archive.blender.org/developer/F9335412/PXL_20201120_101134465.jpg) Issue #2: Lack of cache invalidation on driver changes. As Philipp mentioned, this happens in scenario without the dependency graph cycle as well. This is a bug. Although, can not give an immediate suggestion of a preferred fix for it at this time.

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Sequencer: Driver on any strip property does not invalidate its cache [prefetch frames] #82776