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IDProjectCategoryView StatusDate SubmittedLast Update
0000106Zandronum[All Projects] Bugpublic2010-10-12 22:482018-08-23 05:23
Assigned ToLeonard 
PlatformMicrosoftOSWindowsOS VersionXP/Vista/7
Product Version98c 
Target Version3.1Fixed in Version3.1 
Summary0000106: Client mispredicts its z position in swimmable water online
DescriptionWith a high ping, the viewpoint starts to "teleport/flicker" from being above the surface to being below it and vice versa. Very disorienting.
Steps To Reproduce1. zandronum.exe -file swimmable_water_01.wad -host
2. Connect a client to the server with an emulated ping of 300 and join the game.
3. Enter the water sectors and hold +jump while moving around.
4. When for instance releasing +forward, the mispredictions will occur.
Additional Informationswimmable_water_01.wad
Attached Files? file icon deepwater_view_misprediction_test.wad [^] (956 bytes) 2010-10-12 22:48
png file icon Screenshot_Doom_20120923_235105.png [^] (177,694 bytes) 2012-09-23 22:04

- Relationships
has duplicate 0002637closed Player prediction: desync with underwater sectors. 
related to 0000130closedTorr Samaho client prediction is sometimes wrong 
related to 0002298resolvedLeonard Ancient +jump misprediction that harks back to early Skulltag days 
related to 0002295resolvedLeonard Wall-jitter misprediction issue with high ping 

-  Notes
User avatar (0000347)
unknownna (updater)
2010-10-12 22:52

Hold jump while running or standing still in the water to get the effect.
User avatar (0004787)
unknownna (updater)
2012-09-23 22:04

As you can see in the attached screenshot, the client greatly mispredicts its z position. I'm standing still in the water while holding +jump.
User avatar (0018275)
Leonard (developer)
2017-09-11 17:37

Exactly the same problem as in 2295.

The problem can also be reproduced with this test wad by simply typing "+forward;wait;-forward" in console with 200 ping.

The physics code that uses the ticcmd this time is located here:
In p_mobj.cpp, line 2906:

        if (mo->waterlevel == 0 || (mo->player &&
            !(mo->player->cmd.ucmd.forwardmove | mo->player->cmd.ucmd.sidemove)))
User avatar (0018364)
Torr Samaho (administrator)
2017-09-24 15:25

Thanks for the fix! I added your patch.
User avatar (0019210)
StrikerMan780 (reporter)
2018-05-07 01:14
edited on: 2018-05-07 01:17

Tested in the latest 3.1 build with Gamer's proxy set to 300 ping. No prediction issues. Seems solid with ping randomization on as well.

User avatar (0019387)
unknownna (updater)
2018-08-23 05:23

It seems to work rather well, however, it tends to desync and jitter when holding +jump and moving between the water sectors and the regular ones.
It seems to particularly happen when moving up to the regular sectors from the water, which leads me to believe it's related to the "jitter when standing on ledge of raising floors and slopes" issue (which as far as I can remember, is the final major movement misprediction left).

By the way, thank you very much for fixing all these old prediction issues, I'm incredibly grateful for it. Excellent work, thank you.

Issue Community Support
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Supporters: unknownna ZzZombo Dark-Assassin mifu
Opponents: No one explicitly opposes this issue yet.

- Issue History
Date Modified Username Field Change
2010-10-12 22:48 unknownna New Issue
2010-10-12 22:48 unknownna File Added: deepwater_view_misprediction_test.wad
2010-10-12 22:52 unknownna Note Added: 0000347
2011-07-18 06:36 unknownna Relationship added related to 0000130
2012-06-09 13:22 Torr Samaho Category General => Bug
2012-09-23 22:04 unknownna Note Added: 0004787
2012-09-23 22:04 unknownna Priority low => high
2012-09-23 22:04 unknownna Severity minor => major
2012-09-23 22:04 unknownna Summary mispredicted viewpoint in swimmable water online => Client mispredicts its z position in swimmable water online
2012-09-23 22:04 unknownna Steps to Reproduce Updated View Revisions
2012-09-23 22:04 unknownna Additional Information Updated View Revisions
2012-09-23 22:04 unknownna File Added: Screenshot_Doom_20120923_235105.png
2012-09-24 09:09 unknownna Status new => confirmed
2015-06-17 03:55 unknownna Relationship added related to 0002298
2017-09-11 17:06 Dusk Relationship added has duplicate 0002637
2017-09-11 17:06 Dusk Status confirmed => needs review
2017-09-11 17:06 Dusk Relationship added related to 0002295
2017-09-11 17:37 Leonard Note Added: 0018275
2017-09-11 18:48 Dusk Target Version => 3.1
2017-09-24 15:25 Torr Samaho Note Added: 0018364
2017-09-24 15:26 Torr Samaho Status needs review => needs testing
2017-10-23 15:05 Leonard Status needs testing => assigned
2017-10-23 15:05 Leonard Assigned To => Leonard
2017-10-23 15:06 Leonard Status assigned => needs testing
2018-05-07 01:14 StrikerMan780 Note Added: 0019210
2018-05-07 01:17 StrikerMan780 Note Edited: 0019210 View Revisions
2018-05-07 09:55 Leonard Status needs testing => resolved
2018-05-07 09:55 Leonard Resolution open => fixed
2018-05-07 09:55 Leonard Fixed in Version => 3.1
2018-08-23 05:23 unknownna Note Added: 0019387
2018-08-23 05:23 unknownna Status resolved => feedback
2018-08-23 05:23 unknownna Resolution fixed => reopened

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