Subpanels flicker when expanding panel that has moved #79014

New Issue

Braden Currah · 2020-07-17T07:06:41+02:00

Braden Currah commented

2020-07-17 07:06:41 +02:00

System Information
Operating system: Windows-10-10.0.20161-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-07-12 09:05, hash: f319eec881
Worked: Persistent issue throughout 2.8x.

Short description of error
Certain combinations of minimizing and maximizing the physics properties panels (described below) will cause the element to flash near the bottom of the screen for a frame.

Exact steps for others to reproduce the error

With any object selected, enable two (or more) physics properties for the object.
Minimize the final panel, and then the first.
Maximize the final panel.

Observations
The differences previously mentioned are simply due to a lack of subpanels or panel length.
A second jump appears to sometimes happen when maximizing the final panel after changing the panel type, though I cannot reproduce this reliably.

If the formatting of this video is as terrible as it seems, please let me know how to fix it.
ezgif.com-crop.mp4

**System Information** Operating system: Windows-10-10.0.20161-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87 **Blender Version** Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-07-12 09:05, hash: `f319eec881` Worked: Persistent issue throughout 2.8x. **Short description of error** Certain combinations of minimizing and maximizing the physics properties panels (described below) will cause the element to flash near the bottom of the screen for a frame. **Exact steps for others to reproduce the error** 1. With any object selected, enable two (or more) physics properties for the object. 2. Minimize the *final* panel, and then the first. 3. Maximize the final panel. **Observations** The differences previously mentioned are simply due to a lack of subpanels or panel length. A second jump appears to sometimes happen when maximizing the final panel after changing the panel type, though I cannot reproduce this reliably. If the formatting of this video is as terrible as it seems, please let me know how to fix it. [ezgif.com-crop.mp4](https://archive.blender.org/developer/F8700803/ezgif.com-crop.mp4)

Braden Currah commented

2020-07-17 07:06:41 +02:00

Added subscriber: @TakingFire

Braden Currah changed title from ~~Interface flicker when minimizing physics panels~~ to Interface flicker when maximizing physics panels

2020-07-17 07:22:44 +02:00

Germano Cavalcante commented

2020-07-17 15:13:03 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-07-17 15:13:03 +02:00

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

Germano Cavalcante commented

2020-07-17 15:13:03 +02:00

I can confirm.
I also saw the same behavior on the modifier panels.
I can't reproduce the problem in 2.80

I can confirm. I also saw the same behavior on the modifier panels. I can't reproduce the problem in 2.80

Hans Goudey commented

2020-07-17 16:34:15 +02:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2020-07-17 16:34:15 +02:00

Interesting. Here is the offending frame of the animation:

The key information is that the locations of subpanels don't update while their parent panel is closed. So because the collision
panel is closed first, the subpanels are left at the bottom of the region. Then the first panel is closed, moving the collision panel
up, so when it opens again its subpanels are still at the bottom for a single frame.

I wonder why the subpanel locations don't update on the same redraw as the panel is drawn open.

Interesting. Here is the offending frame of the animation: ![image.png](https://archive.blender.org/developer/F8701809/image.png) The key information is that the locations of subpanels don't update while their parent panel is closed. So because the collision panel is closed first, the subpanels are left at the bottom of the region. Then the first panel is closed, moving the collision panel up, so when it opens again its subpanels are still at the bottom for a single frame. I wonder why the subpanel locations don't update on the same redraw as the panel is drawn open.

Hans Goudey commented

2020-07-17 18:23:21 +02:00

Added subscribers: @JulianEisel, @ideasman42

Hans Goudey commented

2020-07-17 18:23:21 +02:00

In #79014#980977, @HooglyBoogly wrote:
I wonder why the subpanel locations don't update on the same redraw as the panel is drawn open.

Okay, this is because the panel header handler operates on the panel right before the next redraw, but the panel alignment code happens
in the layout step, which happens before drawing. The process looks like this:

Layout	Draw	Handlers (close panel)	Draw (Bad subpanel offset)	Layout (corrects subpanel offsets)	Draw	etc..
I see two possible solutions:

Refactor the panel alignment code so that it runs at the start of the drawing phase if necessary.
Align subpanels whether they are visible or not.

The 2nd option is definitely quicker, but I'm not sure I like it as much. Figuring out whether to align or not is the worst part of the panel code
right now IMO, maybe it would be good to refactor that anyway. I'd be interest to hear @JulianEisel's / @ideasman42's opinion though.

> In #79014#980977, @HooglyBoogly wrote: > I wonder why the subpanel locations don't update on the same redraw as the panel is drawn open. Okay, this is because the panel header handler operates on the panel right before the next redraw, but the panel alignment code happens in the `layout` step, which happens before drawing. The process looks like this: |Layout|Draw|Handlers **(close panel)**|Draw **(Bad subpanel offset)**|Layout **(corrects subpanel offsets)**|Draw|etc..| | -- | -- | -- | -- | -- | -- | -- | I see two possible solutions: 1. Refactor the panel alignment code so that it runs at the start of the drawing phase if necessary. 2. Align subpanels whether they are visible or not. The 2nd option is definitely quicker, but I'm not sure I like it as much. Figuring out whether to align or not is the worst part of the panel code right now IMO, maybe it would be good to refactor that anyway. I'd be interest to hear @JulianEisel's / @ideasman42's opinion though.

Hans Goudey changed title from ~~Interface flicker when maximizing physics panels~~ to Subpanels flicker when expanding panel that has moved

2020-07-17 18:24:36 +02:00

Philipp Oeser removed the

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Subpanels flicker when expanding panel that has moved #79014