bugfix(skirmish): Set consistent seed values for skirmish games to prevent mismatches for restarted skirmish games by Caball009 · Pull Request #2270 · TheSuperHackers/GeneralsGameCode

Caball009 · 2026-02-08T01:22:07Z

Closes Replay will mismatch 100% when Skirmish Game is recorded after RESTART GAME #2269

This PR makes the seed value consistent for started vs. restarted skirmish games, and fixes a bug that causes replays of restarted skirmish game to always mismatch.

TODO:

Replicate in Generals.

greptile-apps · 2026-02-08T01:24:05Z

Greptile Overview

Greptile Summary

This PR adjusts random seed initialization for skirmish games so that starting a skirmish and restarting it reuse consistent seed values, preventing replay mismatches (especially for restarted skirmish games).

Key changes:

SkirmishGameOptionsMenu.cpp now seeds the game-logic RNG with TheSkirmishGameInfo->getSeed() only for true skirmish (multiplayer) maps, and explicitly uses seed 0 for campaign/scenario maps launched via the skirmish menu.
QuitMenu.cpp caches a seed before clearGameData(FALSE) and uses it when restarting the mission (non-replay restart path) so skirmish restarts can preserve the original seed.

Main issue found: the new skirmish seed caching relies on a debug-only assertion for TheSkirmishGameInfo validity; in non-debug builds a null TheSkirmishGameInfo with GAME_SKIRMISH could still lead to a null dereference when computing seed.

Confidence Score: 3/5

This PR is close to mergeable but has a potential null-dereference path in non-debug builds that should be addressed.
Seed handling changes are localized and align with deterministic/non-deterministic expectations, but restartMissionMenu() currently relies on DEBUG_ASSERTCRASH to guarantee TheSkirmishGameInfo validity before dereferencing it to compute seed. If asserts are compiled out, an unexpected null TheSkirmishGameInfo with GAME_SKIRMISH would crash.
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

Important Files Changed

Filename	Overview
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp	Caches skirmish seed before clearGameData and uses it in InitRandom() on restart; adds debug assertion tying TheSkirmishGameInfo presence to GAME_SKIRMISH. Potential issue: release builds can still dereference null if TheSkirmishGameInfo is unexpectedly null.
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/SkirmishGameOptionsMenu.cpp	Moves InitGameLogicRandom() seeding into branches: skirmish uses TheSkirmishGameInfo seed, non-skirmish forces seed 0 for solo campaign maps selectable via skirmish menu. Change appears consistent with intended deterministic non-skirmish behavior.

Sequence Diagram

sequenceDiagram
    participant UI as GUI (Quit/Skirmish Menus)
    participant SGI as TheSkirmishGameInfo
    participant GL as TheGameLogic
    participant RNG as RandomValue (InitRandom/InitGameLogicRandom)
    participant REC as TheRecorder
    participant MS as TheMessageStream

    Note over UI: Starting game from Skirmish menu
    UI->>SGI: startGame(0)
    UI->>UI: determine isSkirmish via MapMetaData.m_isMultiplayer
    alt isSkirmish
        UI->>RNG: InitGameLogicRandom(SGI.getSeed())
        UI->>MS: append MSG_NEW_GAME(GAME_SKIRMISH, ...)
    else non-skirmish scenario map
        UI->>RNG: InitGameLogicRandom(0)
        UI->>MS: append MSG_NEW_GAME(GAME_SINGLE_PLAYER, ...)
    end

    Note over UI: Restarting from Quit menu
    UI->>UI: gameMode = GL.getGameMode()
    UI->>UI: seed = (SGI != nullptr ? SGI.getSeed() : 0)
    UI->>GL: clearGameData(FALSE)
    UI->>REC: getCurrentReplayFilename()
    alt replayFile not empty
        UI->>REC: playbackFile(replayFile)
    else new game restart
        UI->>MS: append MSG_NEW_GAME(gameMode, diff, rankPoints, fps)
        UI->>RNG: InitRandom(seed)
    end

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Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

Caball009 · 2026-02-08T17:35:31Z

I did find a single case where the game would start a new GAME_SINGLE_PLAYER game bit without using a non-zero seed value. I've added that to this PR for more consistent seed values.

…maps).

…ayer maps).

Caball009 · 2026-02-09T02:11:35Z

EDIT: Maybe I didn't properly explain what I documented here. The findings below explain how the seed value is set for different game modes. I noted the execution flow with the current changes of this PR. TheGameInfo ... && TheSkirmishGameInfo ... indicate what the values of these globals are inside the restartMissionMenu function.

Here are the results of my testing with this PR:

1. Campaign (GAME_SINGLE_PLAYER):
Start: doGameStart -> InitRandom( 0 )
Restart: restartMissionMenu -> InitRandom( (gameMode == GAME_SKIRMISH) ? TheSkirmishGameInfo->getSeed() : 0 )
TheGameInfo == nullptr && TheSkirmishGameInfo == nullptr

2. Challenges (GAME_SINGLE_PLAYER):
Start: ChallengeMenuSystem -> InitRandom( 0 )
Restart: restartMissionMenu -> InitRandom( (gameMode == GAME_SKIRMISH) ? TheSkirmishGameInfo->getSeed() : 0 )
TheGameInfo != nullptr && TheSkirmishGameInfo == nullptr

3. Skirmish, single player map / scenario (GAME_SINGLE_PLAYER):
Start: reallyDoStart -> InitGameLogicRandom( 0 )
Restart: restartMissionMenu -> InitRandom( (gameMode == GAME_SKIRMISH) ? TheSkirmishGameInfo->getSeed() : 0 )
TheGameInfo == nullptr && TheSkirmishGameInfo == nullptr

4. Skirmish, multiplayer map (GAME_SKIRMISH):
Start: reallyDoStart -> InitGameLogicRandom( TheSkirmishGameInfo->getSeed() )
Restart: restartMissionMenu -> InitRandom( (gameMode == GAME_SKIRMISH) ? TheSkirmishGameInfo->getSeed() : 0 )
TheGameInfo != nullptr && TheSkirmishGameInfo != nullptr

Caball009 · 2026-02-09T02:19:38Z

If we ever to enable replays for campaign / challenge / single player scenarios, we may need to verify that this issue doesn't happen there as well. I don't see anything that could still present an issue in that regard, though.

xezon · 2026-02-09T07:44:58Z

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/SkirmishGameOptionsMenu.cpp


 	if (isSkirmish)
 	{
+		InitGameLogicRandom(TheSkirmishGameInfo->getSeed());


Why do this change? Shouldn't it be responsibility of whoever set seed in TheSkirmishGameInfo? Now this responsibility has shifted to this function instead.

This line was only changed because of the change below this for single player maps.

With regard to the setting of the seed value, that's already part of the GameInfo constructor.

The restart function sets 0 as seed value for skirmish single player maps, so this function should as well. The restart function cannot use the seed value for skirmish single player maps because TheSkirmishGameInfo is null.

I do not understand. Does this mean, when !isSkirmish, then TheSkirmishGameInfo not null here, but will be null on mission restart?

If yes, does that not indicate a bug elsewhere?

TheSkirmishGameInfo is never null in reallyDoStart, otherwise it'd have crashed in the original code.

It's null in restartMissionMenu for skirmish single player mission. I agree that's unexpected, but it works without apparent issue.

Ok that is very strange. Perhaps that warrants a follow up investigation?

xezon · 2026-02-09T07:47:23Z

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

-		//else
-		//	InitGameLogicRandom(GameClientRandomValue(0, INT_MAX - 1));
+
+		InitRandom(seed);


According to your list:

reallyDoStart -> InitGameLogicRandom( TheSkirmishGameInfo->getSeed() )

Wouldn't this mean that this needs to do:

InitGameLogicRandom( TheSkirmishGameInfo->getSeed() ) then?

Isn't that what I'm doing here?

Currently:

InitRandom( TheSkirmishGameInfo->getSeed() );

Expected:

InitGameLogicRandom( TheSkirmishGameInfo->getSeed() );

That's a good point. It's not clear why the former is used and sometimes the latter. The important point, though, is that InitRandom also sets the logical seed values, which are the only seed values that are part of the CRC computation.

I think we should make reallyDoStart use InitRandom, and perhaps check other places if they should also use InitRandom instead of InitGameLogicRandom.

Ok maybe make a follow up investigation. Is not directly related to this fix.

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

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GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

greptile-apps

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GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

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GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

xezon

Looks like this is correct then.

xezon · 2026-02-10T19:04:16Z

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

+	// TheSuperHackers @bugfix Caball009 07/02/2026 Reuse the previous seed value for the new skirmish match to prevent mismatches.
+	// Campaign, challenge, and skirmish single-player scenarios all use GAME_SINGLE_PLAYER and are expected to use 0 as seed value.
+	DEBUG_ASSERTCRASH((TheSkirmishGameInfo != nullptr) == (gameMode == GAME_SKIRMISH), ("Unexpected game mode on map / mission restart"));
+	const UnsignedInt seed = (TheSkirmishGameInfo) ? TheSkirmishGameInfo->getSeed() : 0;


Superfluous ()

xezon · 2026-02-10T19:04:52Z

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp

-		//else
-		//	InitGameLogicRandom(GameClientRandomValue(0, INT_MAX - 1));
+
+		InitRandom(seed);


Ok maybe make a follow up investigation. Is not directly related to this fix.

Caball009 added Bug Something is not working right, typically is user facing Major Severity: Minor < Major < Critical < Blocker Stability Concerns stability of the runtime labels Feb 8, 2026

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Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp Show resolved Hide resolved

Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp Outdated Show resolved Hide resolved

Caball009 added 2 commits February 9, 2026 02:47

Fixed incorrect seed value for restarted skirmish games (multiplayer …

e3f7584

…maps).

Fixed incorrect seed value for newly started skirmish games (singlepl…

45fa3ea

…ayer maps).

Caball009 force-pushed the fix_bug_skirmish_restart_seed_values branch from 6dacb8a to 45fa3ea Compare February 9, 2026 01:49

Caball009 changed the title ~~bugfix(skirmish): Avoid mismatches for restarted skirmish games~~ bugfix(skirmish): Set consistent seed value for skirmish games to prevent mismatches for restarted skirmish games Feb 9, 2026

Caball009 changed the title ~~bugfix(skirmish): Set consistent seed value for skirmish games to prevent mismatches for restarted skirmish games~~ bugfix(skirmish): Set consistent seed values for skirmish games to prevent mismatches for restarted skirmish games Feb 9, 2026

xezon reviewed Feb 9, 2026

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Caball009 added 2 commits February 9, 2026 19:29

Changed conditional for seed value.

6913185

Added game mode assertion.

f72bc0e

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GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/QuitMenu.cpp Show resolved Hide resolved

Expanded assertion.

4b6d3dc

Caball009 force-pushed the fix_bug_skirmish_restart_seed_values branch from 3208aa9 to 4b6d3dc Compare February 9, 2026 19:34

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Changed assertion text.

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Greptile Overview

Greptile Summary

Confidence Score: 3/5

Important Files Changed

Sequence Diagram

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Caball009 commented Feb 8, 2026 •

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