MantisBT - Zandronum
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0000706Zandronum[All Projects] Bugpublic2012-03-12 16:042014-10-12 14:02
Edward-san 
TIHan 
normalmajoralways
acknowledgedopen 
98d 
 
0000706: Moving down sector elevator desyncs height of spawned projectiles
I noticed that when I was playing Hell Revealed 2 map 31 online in the elevator area:
get the plasma rifle with a lot of ammo and get into the sector, activate the switch which lowers the elevator and you'll see this:
time by time if you shoot the plasma rifle, the starting position of the projectile gets lower, until it disappears completely.
This happens also for the projectiles of the monsters if they are in the area.
Also, if you try to jump, it seems the player is trying to enter down inside the floor.

This happens with 98d and also with latest revision, 3402.
server command:
./skulltag -host 1 -iwad doom2.wad -file hr2final.wad hr2-final-fix.wad -warp 31 -skill 4 -nomonsters -nobroadcast

client command:
./skulltag -connect localhost -iwad doom2.wad -file hr2final.wad hr2-final-fix.wad

See the demo. This is recorded with revision 3402.
No tags attached.
related to 0000055closed Torr Samaho misprediction of player position when opening doors and using lifts online 
related to 0000791acknowledged TIHan Doors opening then jolting into their hold position 
related to 0001957new  Clientside sector prediction for lines that the client activates 
? elevatorbug.cld (131,719) 2012-03-12 16:04
/tracker/file_download.php?file_id=465&type=bug
? elevatorbug1.cld (171,446) 2012-03-12 16:51
/tracker/file_download.php?file_id=466&type=bug
? hr2_floor_test_01.wad (6,798) 2012-03-28 17:21
/tracker/file_download.php?file_id=482&type=bug
Issue History
2012-03-12 16:04Edward-sanNew Issue
2012-03-12 16:04Edward-sanFile Added: elevatorbug.cld
2012-03-12 16:49Edward-sanNote Added: 0002809
2012-03-12 16:51Edward-sanNote Edited: 0002809bug_revision_view_page.php?bugnote_id=2809#r1455
2012-03-12 16:51Edward-sanFile Added: elevatorbug1.cld
2012-03-18 21:02Torr SamahoNote Added: 0002827
2012-03-18 21:03Torr SamahoStatusnew => feedback
2012-03-28 17:21unknownnaFile Added: hr2_floor_test_01.wad
2012-03-28 17:21unknownnaNote Added: 0002965
2012-03-28 19:07Edward-sanNote Added: 0002966
2012-03-28 19:07Edward-sanStatusfeedback => new
2012-04-07 00:24TIHanNote Added: 0003159
2012-04-07 00:24TIHanAssigned To => TIHan
2012-04-07 00:24TIHanStatusnew => acknowledged
2012-04-07 00:25TIHanNote Edited: 0003159bug_revision_view_page.php?bugnote_id=3159#r1647
2012-04-29 01:55TIHanRelationship addedrelated to 0000791
2012-04-29 17:19TIHanRelationship addedrelated to 0000055
2012-06-09 13:22Torr SamahoCategoryGeneral => Bug
2013-01-13 13:35Edward-sanNote Added: 0005769
2014-10-12 14:02Torr SamahoRelationship addedrelated to 0001957

Notes
(0002809)
Edward-san   
2012-03-12 16:49   
(edited on: 2012-03-12 16:51)
It seems that the client thinks the elevator speed is lower than the right one. In fact, when I shoot with any hitscan weapon the puff's position is lower than yours. Also, when you wait a lot, at a certain point there's a high speed lowering down. The server's current elevator is near the stopping position, but the client thinks the elevator's current position is a lot higher.

This effect is visible with the second record demo. You have to wait a lot of time, I don't know how to measure the right time this happens.

(0002827)
Torr Samaho   
2012-03-18 21:02   
Can somebody create a minimal example wad?
(0002965)
unknownna   
2012-03-28 17:21   
Edward-san, can you reproduce the bug with my example WAD?
(0002966)
Edward-san   
2012-03-28 19:07   
Yes, just wait a bit and begin shooting with the pistol. At the beginning there's nothing notable, but wait a minute and refire again. The spawned projectile is positioned lower than the cross.
(0003159)
TIHan   
2012-04-07 00:24   
(edited on: 2012-04-07 00:25)
Me and Edward had a good long discussion about this, which I was able to reproduce the issue in two ways:
1. With unlagged off and with 500 ping - the ping determines the gap between where you fired and where it actually hits - with hitscan weapons.
2. With unlagged on, I start the floor moving down with 500 ping, everything feels good. If I bring the ping down to 0 while the floor is moving, you can clearly see the gap in hitscan and projectiles.

Notes: Apparently projectile weapons do have a gap, but it's very hard to notice without fluctuating the ping constantly. This is due to how latency works with floors; as we have no prediction of moving sectors and/or no unlagged on projectile weapons right when they fire (which we do not want that).

This needs to be thoroughly discussed and probably do something about it after 98e.

(0005769)
Edward-san   
2013-01-13 13:35   
zandronum 1.0 is released, so I believe this should be fixed in 1.1.