MantisBT - Zandronum
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IDProjectCategoryView StatusDate SubmittedLast Update
0002637Zandronum[All Projects] Bugpublic2016-02-14 19:002017-09-11 17:06
ReporterLeonard 
Assigned To 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionduplicate 
PlatformMicrosoftOSWindowsOS VersionXP/Vista/7
Product Version2.1 
Target VersionFixed in Version 
Summary0002637: Player prediction: desync with underwater sectors.
DescriptionThe client mispredicts its player position when interacting with underwater sectors.

To Torr: I did some experiments with my version of the player prediction to try and fix this and by chance I found something that partially fixes the issue. I will make a patch for the current version when I get the time but to give a short explanation: I simply recalculated the waterlevel of the player's mobj when restoring the prediction and stopped saving the waterlevel for each tick.
Steps To Reproduce-host a server with the attached test wad (prdict2.wad)
-join said server with an emulated ping of 200
-in the water sector, press +jump and never release
-aim slightly down
-slightly tap +forward
-the prediction will kind of mess up and you will jitter in and out of the water

It's even worse when you do that while getting out of the water by hugging the edge.
Additional InformationHappens both in 2.1.2 and 3.0.
TagsNo tags attached.
Relationships
duplicate of 0000106closed Leonard Client mispredicts its z position in swimmable water online 
Attached Files? prdict2.wad (3,354) 2016-02-14 19:00
https://zandronum.com/tracker/file_download.php?file_id=1742&type=bug
diff waterfix.diff (1,383) 2016-02-15 22:10
https://zandronum.com/tracker/file_download.php?file_id=1746&type=bug
? prdict2.cld (62,411) 2016-02-28 14:11
https://zandronum.com/tracker/file_download.php?file_id=1750&type=bug
Issue History
Date ModifiedUsernameFieldChange
2016-02-14 19:00LeonardNew Issue
2016-02-14 19:00LeonardFile Added: prdict2.wad
2016-02-15 22:10LeonardNote Added: 0014448
2016-02-15 22:10LeonardFile Added: waterfix.diff
2016-02-22 19:10DuskStatusnew => needs review
2016-02-28 10:39Torr SamahoNote Added: 0014510
2016-02-28 10:39Torr SamahoAssigned To => Torr Samaho
2016-02-28 10:39Torr SamahoStatusneeds review => feedback
2016-02-28 14:10LeonardNote Added: 0014513
2016-02-28 14:10LeonardStatusfeedback => assigned
2016-02-28 14:11LeonardFile Added: prdict2.cld
2016-02-28 20:56Torr SamahoNote Added: 0014516
2017-09-11 17:06DuskStatusassigned => closed
2017-09-11 17:06DuskAssigned ToTorr Samaho =>
2017-09-11 17:06DuskResolutionopen => duplicate
2017-09-11 17:06DuskRelationship addedduplicate of 0000106

Notes
(0014448)
Leonard   
2016-02-15 22:10   
I attached the patch I was talking about.
It "partially" fixes the issue because now when simply hitting +forward there is a very slight jitter similar to this issue.
(0014510)
Torr Samaho   
2016-02-28 10:39   
Can you make a demo of the effect in 3.0, preferably based on the current head of 3.0?
(0014513)
Leonard   
2016-02-28 14:10   
Attached the requested demo.
The head at the time of recording was this commit.
Notice that playing back the demo with waterfix.diff applied on top reduces the effect a lot.
(0014516)
Torr Samaho   
2016-02-28 20:56   
Thanks for the demo. The behavior seems indeed better with your fix, but, as you already mentioned, it still doesn't seem to work fully. Guess we should look into this in more detail to find out why this is failing.