0000042: player death sequence starts at a much higher floor height

Notes
(0000115) Wartorn (reporter) 2010-09-20 22:27	Verified in 98d-2937. I don't think this is an easy fix, though.

(0000116) unknownna (updater) 2010-09-20 22:37 edited on: 2010-09-21 03:50	Added a second demo. The client shooting the other client has an emulated ping of 335ms. It seemed very probable to happen with that setup; where the shooter had a higher ping than the one being shot. The desynchronization is that the client of the shooter sees the other client as being on a higher floor, but the other client doesn't see itself as being on the higher floor. The demo is recorded from the shooter's POV, so coop-spying the other client won't allow you to see the desynchronization as it truly is.

(0000117) Wartorn (reporter) 2010-09-20 22:54	Some additional insight: It seems to be really angle and position dependent, I could easily reproduce the problems based on the locations given in the demos, but not anywhere else.

(0000261) unknownna (updater) 2010-10-04 12:06 edited on: 2010-11-02 02:54	Made an example WAD and a demo to it. It has nothing to do with the death sequence. EDIT: Made another example WAD with a demo to it. Demo uses 98c. Had no ping emulation. A simple pistol shot makes the other player flicker up to the higher floor.

(0001471) unknownna (updater) 2011-04-26 01:06 edited on: 2011-04-26 01:19	Thanks to EmZee712 and Fluffles, we can now easily reproduce this issue. Steps to reproduce: 1. Start a standard server with the example WAD loaded. 2. Connect two clients to the server. 3. Join the game with client A. 4. Bump into the diagonal wall with client A. Edit: Hmm, it seems that this only happens in 98e. It started to occur in build 3122M (software 3D floors).

(0001472) Torr Samaho (administrator) 2011-04-26 01:37	> Hmm, it seems that this only happens in 98e. It started to occur in build 3122M (software 3D floors). But it only happens online?

(0001473) unknownna (updater) 2011-04-26 01:46 edited on: 2011-04-26 01:48	Yes. Another strange thing is that your bullet puffs are affected by it as well. This does not happen offline. But the bullet puff issue is also present in 98d.

(0001476) unknownna (updater) 2011-04-26 04:38	IIRC, you fixed this issue in that build.

(0001721) Torr Samaho (administrator) 2011-05-21 22:28	If this fixes the issue then I know what's causing it. In this case the fix will increase net traffic.

(0001725) unknownna (updater) 2011-05-21 23:14 edited on: 2011-05-21 23:17	Very nice. It fixed the issue. But the issue is still present for your own puffs though. > In this case the fix will increase net traffic. No need to worry about this.

(0001727) Torr Samaho (administrator) 2011-05-21 23:37	> But the issue is still present for your own puffs though. I'm sure that this has the same reason: To save bandwidth the server only sent the player's position at 16 bit accuracy. When at a sector boundary, this could cause a player to be rounded to the neighboring sector and since a player can't be inside the floor, it was then raised to the floor height. I made the server sent the x/y position at full precision, fixing the problems for players. I really don't want to send the puffs at full precision though, since there are potentially a lot of puffs, this would eat a lot of bandwidth. > No need to worry about this. Well, at latest if a broadband connection is not enough anymore for simple deathmatch, we need to worry about these things.

(0001728) unknownna (updater) 2011-05-22 00:14	> Well, at latest if a broadband connection is not enough anymore for simple deathmatch, we need to worry about these things. It was only directed towards this particular case. > I'm sure that this has the same reason: To save bandwidth the server only sent the player's position at 16 bit accuracy. When at a sector boundary, this could cause a player to be rounded to the neighboring sector and since a player can't be inside the floor, it was then raised to the floor height. I made the server sent the x/y position at full precision, fixing the problems for players. I really don't want to send the puffs at full precision though, since there are potentially a lot of puffs, this would eat a lot of bandwidth. I see. I wonder where Spleen went. If ST had client-side puff prediction, this wouldn't be an issue, right? So the visual error has no effect on the gameplay? In that case, it's not so important to have it fixed.

(0001729) Torr Samaho (administrator) 2011-05-22 00:28	> I wonder where Spleen went. AFAIK he is too busy with RL issues. > If ST had client-side puff prediction, this wouldn't be an issue, right? Yes, puff prediction is a very difficult issue though. Unless it is 100% accurate (which likely is impossible to achieve), IMHO it's better not to do any puff prediction. > So the visual error has no effect on the gameplay? Other than the displayed puff position being off, it shouldn't have any effect.

(0001941) unknownna (updater) 2011-07-24 07:17 edited on: 2011-07-24 07:20	> Yes, puff prediction is a very difficult issue though. Unless it is 100% accurate (which likely is impossible to achieve), IMHO it's better not to do any puff prediction. It seems that ZDaemon's puff prediction works in a certain way. Clients only predict all the puffs that don't hit anything. But the puffs that hit something are delayed. So no blood puffs are predicted locally. Would it be possible to have a similar setup in ST?

(0001942) Torr Samaho (administrator) 2011-07-24 12:01	> Clients only predict all the puffs that don't hit anything. But the puffs that hit something are delayed. So no blood puffs are predicted locally. Would it be possible to have a similar setup in ST? This would be possible but still has the same problem: Unless you find a way to make the prediction perfectly accurate the client doesn't know exactly how many of the puffs hit and how many miss. So if you do it like this, it's very possible that you see too few or too many puffs.

(0002117) unknownna (updater) 2011-08-11 17:52	The player z position still desyncs if the other player jumps near the ledges when "sv_aircontrol" is set to 0 and "compat_limited_airmovement" is set to 1 (oldschool). It looks pretty stupid since the player is seen as skipping from the higher floor to the lower floor rather than jumping.

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Issue History
Date Modified	Username	Field	Change
2010-09-20 21:33	unknownna	New Issue
2010-09-20 21:33	unknownna	File Added: 2010.09.20_22.41.59_dwango5.cld
2010-09-20 22:20	unknownna	File Added: 2010.09.21_00.11.53_dwango5.cld
2010-09-20 22:27	Wartorn	Note Added: 0000115
2010-09-20 22:37	unknownna	Note Added: 0000116
2010-09-20 22:54	Wartorn	Note Added: 0000117
2010-09-21 03:50	unknownna	Note Edited: 0000116	View Revisions
2010-10-04 11:58	unknownna	File Added: playerposition_desync_test.wad
2010-10-04 11:59	unknownna	File Added: 2010.10.04_13.54.58_playerposition_desync_test.cld
2010-10-04 12:06	unknownna	Note Added: 0000261
2010-10-04 12:06	unknownna	Note Edited: 0000261	View Revisions
2010-11-02 02:54	unknownna	Note Edited: 0000261	View Revisions
2010-11-02 02:56	unknownna	File Added: playerposition_desync_test2.wad
2010-11-02 02:56	unknownna	File Added: 2010.11.02_03.47.08_playerposition_desync_test2.cld
2011-04-26 01:04	unknownna	File Added: Screenshot_Doom_20110426_030352.png
2011-04-26 01:05	unknownna	File Added: playerposition_desync_test_03.wad
2011-04-26 01:06	unknownna	Note Added: 0001471
2011-04-26 01:06	unknownna	Status	new => confirmed
2011-04-26 01:06	unknownna	Priority	low => high
2011-04-26 01:06	unknownna	Severity	minor => major
2011-04-26 01:16	unknownna	Note Edited: 0001471	View Revisions
2011-04-26 01:19	unknownna	Note Edited: 0001471	View Revisions
2011-04-26 01:23	unknownna	Priority	high => urgent
2011-04-26 01:37	Torr Samaho	Note Added: 0001472
2011-04-26 01:46	unknownna	Note Added: 0001473
2011-04-26 01:46	unknownna	File Added: Screenshot_Doom_20110426_034442.png
2011-04-26 01:48	unknownna	Note Edited: 0001473	View Revisions
2011-04-26 04:38	unknownna	Note Added: 0001476
2011-05-21 22:28	Torr Samaho	Note Added: 0001721
2011-05-21 22:53	Torr Samaho	Assigned To	=> Torr Samaho
2011-05-21 22:53	Torr Samaho	Status	confirmed => feedback
2011-05-21 23:14	unknownna	Note Added: 0001725
2011-05-21 23:14	unknownna	Status	feedback => assigned
2011-05-21 23:17	unknownna	Note Edited: 0001725	View Revisions
2011-05-21 23:37	Torr Samaho	Note Added: 0001727
2011-05-22 00:14	unknownna	Note Added: 0001728
2011-05-22 00:28	Torr Samaho	Note Added: 0001729
2011-07-24 07:17	unknownna	Note Added: 0001941
2011-07-24 07:20	unknownna	Note Edited: 0001941	View Revisions
2011-07-24 12:01	Torr Samaho	Note Added: 0001942
2011-08-11 17:52	unknownna	Note Added: 0002117
2011-08-11 17:53	unknownna	File Added: Screenshot_Doom_20110811_194709.png
2011-08-11 17:54	unknownna	File Added: playerposition_desync_test_04.wad
2012-06-09 13:22	Torr Samaho	Category	General => Bug

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