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Getting access to the GameMode

Development Discussion C++ Gameplay Programming
#1

How do I get access to the GameMode class I have created from other classes?

For example, imagine you have this:

h…


UCLASS(minimalapi)
class AMyGameGameMode : public AGameMode
{
	GENERATED_UCLASS_BODY()
public:
	FPointSystem* PointSystem;
};

**
cpp…**


AMyGameGameMode::AMyGameGameMode(const class FPostConstructInitializeProperties& PCIP)
	: Super(PCIP)
{
	// set default pawn class to our character
	DefaultPawnClass = AMyGameCharacter::StaticClass();
	HUDClass = AMainHUD::StaticClass();
	PointSystem = new FPointSystem();
}

How do you then go and access the AMyGameGameMode object…

I had a total guessage at it (Obviously it wrong):


AMyGameGameMode* GameMode = Cast<AMyGameGameMode>(AMyGameGameMode::StaticClass());
GameMode->PointSystem....

I see that they seem to be referenced as if they are static classes… How does this work, I find the lack of static declaration confusing if so…

I also tried this:


TSubobjectPtr<AMyGameGameMode> GameMode;
GameMode = PCIP.CreateDefaultSubobject<AMyGameGameMode>(this, TEXT("GameMode"));

But that crashes the loader :smiley:

#2

of course that is wrong, StaticClass is to get the Class for comparaisons and spawning, to get the gamemode, you do this:



AMyGameMode * mymode= Cast<AMyGameMode>(GetWorld()->GetAuthGameMode());

the GetWorld()->GetAuthGameMode(); function gets the current gamemode in any AActor, keep in mind, this wont work on clients on multiplayer game, as clients in a multiplayer game cant access the gamemode becouse the only instance is in the server.

#3

I just tried this before you posted (I thought I was on the right wave length!) but it throws an error:


	AMyGameGameMode* mode = Cast<AMyGameGameMode>(GetWorld()->GetAuthGameMode());

        // Unhandled exception at 0x00007FFCFEB08FC0 (UE4Editor-Engine.dll) in UE4Editor.exe: 0xC0000005: Access violation reading location 0x0000000000000120.

I’ll keep at it… Most likely something silly i’m doing now… however, if you do know… deffo tell me :smiley: Thanks buddoss!

Might be worth noting i’m trying to access it from within the HUD class I created

ca677036fb9de1bf89218235740a2d059db6b25f.png

Related posts: https://answers.unrealengine.com/questions/25153/how-to-get-a-reference-to-my-gamemode-class-instan.html

#4

Looks like those objects are not in the current scope. Perhaps add a member to your HUD to hold a pointer to (or copy of) the game mode and fill it before entering the current state so you have data to look at.

#5

Isn’t this what I have?.. You can see GameMode is of Type ATofuGameMode… and it’s a property of HUD:


/**
 * 
 */
UCLASS()
class TOFUGAME_API AMainHUD : public AHUD
{
	GENERATED_UCLASS_BODY()
public:
	TSubobjectPtr<UHUDElementComponent> TofuPoints;
	virtual void DrawHUD() override;
	ATofuGameGameMode* GameMode;
};
#6

Then somehow it’s not being set. Look at your screenshot - it’s NULL…

I see in your HUD constructor you try to get the game mode and set it - my guess is that it doesn’t exist at that point.

#7

Yes, that’s correct. It’s not there to grab yet… Hopefully someone knows why :smiley: Thanks for your time though matey :slight_smile:

Okay, I hadn’t quite grasped what vblanco was saying as it’s a new part for me… but apparently it’s not working because I am working on client… which I assume means… my pc? rather than a server… I’ll take a look at these PlayerState and GameState thingies… Any other parent declaration place?

#8

Is your HUD object global? If so, perhaps you can have the game mode register itself with your HUD when it comes up.

#9

You should never try to access objects in the constructor because, as VegasRich pointed out, there is a chance that they haven’t been constructed yet. What you should do is override the BeginPlay function and set the pointer there.

#10

Kumppi… The Hud doesn’t have a BeginPlay, are you thinking of StartPlay with the GameMode? If so, I have moved into this now:

Doesn’t make a difference unfortunately… but thanks for the warning.


ATofuGameGameMode::ATofuGameGameMode(const class FPostConstructInitializeProperties& PCIP)
	: Super(PCIP)
{
	// set default pawn class to our character
}

void ATofuGameGameMode::StartPlay()
{
	DefaultPawnClass = ATofuGameCharacter::StaticClass();
	HUDClass = AMainHUD::StaticClass();
}
#11 


void ATofuGameGameMode::StartPlay()
{
	DefaultPawnClass = ATofuGameCharacter::StaticClass();
	HUDClass = AMainHUD::StaticClass();
        HUDClass->GameMode = this;
}

maybe? Hopefully?

#12

Unfortunately that will not work bro… Once again though, cheers for having a try!!!

#13

Isn’t AHUD derived from AActor? If so it should have the BeginPlay function. Weird. Well game mode definitely has it.

#14

Kumppi, you’re right!!! It does end up deriving from AActor… Thanks for slapping me down like the noob I am, hangon lemme see if this works now…

Well looooooky here… It no longer crashes… Now I’ve got to get this GameState working instead which I didn’t realise I was supposed to use instead.

#15

hey jimmy, GameMode only exists on the server, so first of all make sure you only call it on the server :slight_smile: and use the command that vblanko showed you. Don’t use it in the constructor like you’re doing since it might not exist yet there, use it in the BeginPlay. I hope it works out for you

#16

My GameState is empty… Any ideas what might be failing?

I am setting the class up in the gamemode:


GameStateClass = AGameState::StaticClass();

and then inside my huds BeginPlay I am calling


UWorld* world = GetWorld();
	GameState = world->GetGameState<AMainGameState>();
#17 


GameState = Cast<AMainGameState>(world->GetGameState()); // ?
#18

Yeah I had a problem doing it this way.

83519e92ff4571cca0b6e9c28c7bb1bcd7a0355c.png

So you have to declare the template type:



	GameState = Cast<AMainGameState>(world->GetGameState<AMainGameState>());

and then you may aswell get rid of the Cast…

However, even with the Cast it doesn’t seem to return the GameState set up in the GameMode

Related: https://answers.unrealengine.com/questions/52324/42-getting-gamestate-from-world-returns-null.html ?
related: https://forums.unrealengine.com/showthread.php?18473-GameState-uninitialised-in-networking-test

errr… I had a typo… YEHAAA IT WORKs… THANKS ALL… Beers for ALL