0003316: Unlagged is off by one tic every time

MantisBT - Zandronum

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Project

Category

View Status

Date Submitted

Last Update

0003316

Zandronum

[All Projects] Bug

public

2017-10-28 01:45

2024-03-12 06:25

Reporter

Leonard

Assigned To

Leonard

Priority

normal

Severity

major

Reproducibility

always

Status

resolved

Resolution

fixed

Platform

OS Version

Product Version

3.0

Target Version

3.1

Fixed in Version

3.1

Summary

0003316: Unlagged is off by one tic every time

Description

This affects both ping and tic-based unlagged.
As is explained in issue 0003315, P_PlayerThink is called before any mobj ticks and therefore moves.
However, the recording of players positions is done way after their bodies moved for the specified tic:
UNLAGGED_Tick (which calls UNLAGGED_RecordPlayer) is called in G_Ticker while the player's movements are processed in SERVER_Tick (which is what calls G_Ticker afterwards).
This means that the unlagged positions are recorded one tick too late.

Steps To Reproduce

Using the test wad and the debug commit referenced in 0002859:0018627:
-host a server on MAP01 (no need to enable sv_unlagged_debugactors)
-connect and join 2 clients
-align the clients horizontally
-make sure you test this with client 0 so as to not run into issue 0003315
-make sure to have cl_ticsperupdate on 1 so as to not run into 0003317
-shoot the other client
-if you have no latency to the server, you will hit however if you have at least one tic of latency (you may emulate the ping) you will always miss
-whenever you have at least one tic of latency, you are forced to aim right ahead of the player to land a hit (this may explain 0001705:0008281)

Additional Information

With the fix, using the steps to reproduce above, your hits will always land both with ping and gametic-based unlagged.