ID:2539967
 
Resolved
Making a large change to client pixel offsets and then undoing it on the next tick could cause some turfs' visual contents to disappear.
BYOND Version:513
Operating System:Windows 7 Ultimate 64-bit
Web Browser:Chrome 79.0.3945.130
Applies to:Dream Seeker
Status: Resolved (513.1509)

This issue has been resolved.
Descriptive Problem Summary:
So i noticed that sometimes when i changed client pixel offsets stuff with visual contents could stop displaying them, and it's inconsistant too, sometimes couple of tiles breaks, sometimes whole screen worth of vis_contents stops.

Things to notice:
This was experienced by all players that played on my server, at least once.
This also occured upon rapid elevation through z-levels back and forth
This is/was happening to overlays as well, but far less often.

Numbered Steps to Reproduce Problem:
1.Have alot of vis_contents
2.Start changing your client's offset in controlled manner
3.At some point it will start to breakdown
(I also think you should host the server with dream daemon for this.)

This is how it looks
https://cdn.discordapp.com/attachments/323648342099886090/ 670696993722597376/unknown.png
https://cdn.discordapp.com/attachments/323648342099886090/ 670697283129573396/unknown.png

Code Snippet (if applicable) to Reproduce Problem:
I can provide you with "testing enviroment" instead:
https://dropmefiles.com/RmWec

Does the problem occur:
Every time? Or how often?
It's inconsistant, but everyone had it at least once per game.
In other games?
Yes, i tested it both in my game and in testing enviroment.
In other user accounts?
Yes.
On other computers?
Yes, all of my players experienced it.

When does the problem NOT occur?
Well i don't recall vis_contents/overlays breaking down upon normal camera movement at all, only when it's instant or so.

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
I haven't tested it on older versions but i think i've seen this long before 513.

Workarounds:
No workarounds i know of, unless you're not offsetting client's camera it will happen.

The fact that you can only get this to happen intermittently is a problem. I tried out your test case, hosting it in Dream Daemon as you suggested, but I was not able to replicate any issues.

I need more explicit instructions on how to reproduce the bug.
Lummox JR changed status to 'Unverified'
Lummox JR resolved issue with message:
Making a large change to client pixel offsets and then undoing it on the next tick could cause some turfs' visual contents to disappear.