Lag reading viewport depth buffer in LookDev mode #68206

System Information
Operating system: macOS Sierra version 10.12.6
Graphics card: Radeon Pro 55 2048 MB

Blender Version
Broken: ( 2.80 )
Worked: (optional) ( 2.80, 3325b19ee7, branch: blender 2.7, 2019-06-06 )

Short description of error

In LookDev mode, zooming is extremely choppy. This topic was adressed earlier and dismissed a hardware issue. But the problem did not exist in an earlier version, suggesting it probably could be a software related issue. Check the video beneath.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file.

devlook slow zooming.mp4

Added subscriber: @Jelleeey

#89142 was marked as duplicate of this issue

#73827 was marked as duplicate of this issue

#63026 was marked as duplicate of this issue

Added subscriber: @WilliamReynish

How are you zooming? Using the scroll wheel or by using the modifier key and dragging you mouse, or a different way?

Hi William,

I use the scroll wheel to zoom in and out.

Is it also choppy when zooming using modifier+mouse-dragging?

Interesting. Using ctrl + mmb (drag) the zooming goes smooth.

I found the problem. For some reason, unchecking this box in the keymap for zoom in / zoom out resolves the problem. I unchecked this also for the pan and orbit keymap, as i discovered it acts more responsive with this checkbox off. However, maybe it is still a good idea to resolve this weird bug.

EDIT: This solution is not valid as it creates a new problem where the autodepth and 'zoom to mouse position' features are not working anymore.

Added subscriber: @ideasman42

@ideasman42 Unsure how to triage this?

Do you have "Auto Depth" preference enabled?
Does this happen with Factory Settings loaded?

It's possible getting the depth under the cursor is slower in look-dev mode, this only happens once w/ Ctrl-MMB, for mouse wheel it happens on every event because zooming isn't a mode in that case and each event could be over a different surface.

In #68206#745186, @ideasman42 wrote:

Do you have "Auto Depth" preference enabled?

Does this happen with Factory Settings loaded?

It's possible getting the depth under the cursor is slower in look-dev mode, this only happens once w/ Ctrl-MMB, for mouse wheel it happens on every event because zooming isn't a mode in that case and each event could be over a different surface.

I have auto depth enabled and use the factory settings in both versions (working and not working versions). I understand now that the issue is related to the autodepth feature. I understand what you say about the wheel zoom, where it sees every scroll as an event where the autodepth has to be recalculated. However, this does not explain why this behavior is not present in the previous version ( 2.80, 3325b19ee7, branch: blender 2.7, 2019-06-06 ).

Is this issue still looked at?

I checked out the newest version (2.81 alpha ) and the lookdev mode performs well again.

EDIT: The issue still persists. Upon closer inspection it appears that the 2.81 alpha worked because the autodepth was turned off when I tried it. This was because the new build started up with the default user preferences.

Changed status from 'Open' to: 'Resolved'

Changed status from 'Resolved' to: 'Open'

In the 2.81 alpha this issue still appears (Version 2.81 (2.81 2019-09-12)) This issue is really annoying. Could someone please look into this?

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

I can confirm a slight delay in LookDev mode, it can be seen when placing the cursor too.

However the difference isn't much on my system, making profiler results not highlight the cause so easily. Marking this as TODO.

Removed subscriber: @ideasman42

Added subscriber: @ThomasRadeke

Added subscribers: @olyandros, @fclem, @jenkm, @ckohl_art, @Brunomendesgussoni, @iss, @John_Do, @AbidMaqbool, @WickedInsignia, @DanielPaul, @Mets, @lichtwerk, @brecht, @ideasman42

Added subscribers: @xan2622, @MichaelHermann, @HooglyBoogly, @thsampa, @Pasang

After a while, I checked this (and #73827) again and I can no longer reproduce it. (2.90.1 or 2.91 Beta) Maybe it got fixed somewhere along the way.?

This comment was removed by @WickedInsignia

@Jelleeey can you redo this in 2.91 or current daily build? (2.92 alpha).

This issue is still present. I don't see any difference compared to previous versions.

Just tried with 2.91.0 Beta, the lag is still present when Auto Depth is turned on.
I understand that re-using data you already have (depth buffer) is the preferred way to do things, but for zooming you're really just using one pixel of the entire buffer, right?
Wouldn't it be faster to do a single raycast to determine depth than to read a buffer that is only going to become bigger and bigger as monitor resolutions increase?
I'm using a 4K screen. When I resize my Blender window to be ~1/4th of the screen (e.g. Full HD), the lag is gone (or at least not noticable anymore).

I had bought a 4k monitor to use in Blender, but it was a waste of money, as I can't use 'Auto depth', I had to use my old full hd monitor.

OK, with the Viewport in Fullscreen on a 4K Monitor, I can also see the lag again.
@Brunomendesgussoni : For me, the workaround was to turn off Viewport Anti-Aliasing.

In #68206#1047609, @ideasman42 wrote:
@Jelleeey can you redo this in 2.91 or current daily build? (2.92 alpha).

@ideasman42 For me the issue still persists in the newest build (2.92 alpha)

Added subscriber: @2046411367

Added subscribers: @tonpix, @PratikPB2123

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Lag reading viewport depth buffer in LookDev mode #68206