MantisBT - Zandronum
View Issue Details
IDProjectCategoryView StatusDate SubmittedLast Update
0004202Zandronum[All Projects] Bugpublic2024-03-07 09:222024-11-15 06:20
Reporterunknownna 
Assigned To 
PrioritynormalSeveritymajorReproducibilityalways
StatusconfirmedResolutionopen 
PlatformOSOS Version
Product Version3.1 
Target VersionFixed in Version 
Summary0004202: Client postitions desync relative to each other on scrolling floors if there is latency
DescriptionContinued from my report while testing the gametic-unlagged fixes several years ago:

Quote from unknownna
I saw some very bad desync here where both clients disagreed where they were located on the map with unlagged_debug.wad.


If clients have some latency, they will not see the correct position of other players on scrolling floors. The more latency, the further apart the clients are moved. If you lower the latency, the positions correct themselves.

As you can see in the attached screenshot, client A actually stands close to client B, but client B perceives client A as being far away.

Steps To Reproduce1. Start a server with the example wad, unlagged_debug_02.wad
2. Connect 2 clients to the server, make sure one has an emulated ping of 300 to easily reproduce the issue.
3. Join the game with both clients and move closer to each other. They will be at different positions relative to one another.
4. Lower the emulated ping and see the positions sync up properly again.
Additional Information
TagsNo tags attached.
Relationships
related to 0002859resolved Leonard Gametic-based unlagged seemingly goes out of sync often compared to ping-based unlagged 
Attached Files? unlagged_debug_02.wad (12,999) 2024-03-07 09:22
/tracker/file_download.php?file_id=2909&type=bug
png Screenshot_Doom_20240307_100047.png (167,821) 2024-03-07 09:23
/tracker/file_download.php?file_id=2910&type=bug
png
Issue History
Date ModifiedUsernameFieldChange
2024-03-07 09:22unknownnaNew Issue
2024-03-07 09:22unknownnaFile Added: unlagged_debug_02.wad
2024-03-07 09:23unknownnaFile Added: Screenshot_Doom_20240307_100047.png
2024-03-07 09:24unknownnaRelationship addedrelated to 0002859
2024-11-15 06:20unknownnaNote Added: 0024139
2024-11-15 06:20unknownnaStatusnew => confirmed

Notes
(0024139)
unknownna   
2024-11-15 06:20   
From testing the new tick sync fixes, I found out that "cl_predict_players 1" is causing the clients to desync for each other on the fast moving floor for some reason.