Dynamic Material Instance Changing All Occurances

[ConstableCatnip (WeirdOne84)]

In GridMaker.cpp

void AGridMaker::BeginPlay()
{
	Super::BeginPlay();
	
	
	GridArray.SetNum(10);
	for (int32 i = 0; i < GridArray.Num(); ++i)
	{
		GridArray[i].SetNum(10);
	}
	float GridXLocation = 0;
	float GridYLocation = 0;
	for (int32 i = 0; i < GridArray.Num(); ++i)
	{
		for (int32 j = 0; j < GridArray[i].Num(); ++j)
		{
			GridArray[i][j].Location = FVector(GridXLocation, GridYLocation, 10);
			if (UWorld* ThisWorld = GetWorld())
			{
				FVector ActorLocation = FVector(GridXLocation, GridYLocation, 0);
				GridArray[i][j].SetGridActor(Cast<AGridActor>(ThisWorld->SpawnActor(AGridActor::StaticClass(), &ActorLocation)));
				if (GridArray[i][j].GridActor)
				{
					
					if (LinkedMaterial)
					{
						UMaterialInstanceDynamic* Material_Dyn = UMaterialInstanceDynamic::Create(LinkedMaterial, NULL);
						GridArray[i][j].GridActor->SetDynamicMaterialInstance(Material_Dyn, FLinearColor::White);
						
					}										
				}
				
			}
			GridYLocation += 100.f;
		}
		GridXLocation += 100.f;
		GridYLocation = 0;
	}
}

also

bool AGridMaker::SetCellToRoad(int32 XCoordinate, int32 YCoordinate)
{
	if (XCoordinate >= 0 && YCoordinate >= 0 && XCoordinate < GridArray.Num() && YCoordinate < GridArray[XCoordinate].Num())
	{
		GEngine->AddOnScreenDebugMessage(1, 5, FColor::Black, FString::Printf(TEXT("Point is in range")));
		if (GridArray[XCoordinate][YCoordinate].GridActor)
		{
			GEngine->AddOnScreenDebugMessage(1, 5, FColor::Black, FString::Printf(TEXT("Actor is valid")));
			if (GridArray[XCoordinate][YCoordinate].GridActor->GetMarialInstance() != nullptr)
			{
				GEngine->AddOnScreenDebugMessage(1, 5, FColor::Black, FString::Printf(TEXT("Material is Valid")));
				UMaterialInstanceDynamic* Material_Dyn = UMaterialInstanceDynamic::Create(LinkedMaterial, NULL);
				GridArray[XCoordinate][YCoordinate].GridActor->SetDynamicMaterialInstance(Material_Dyn, FLinearColor::Green);
			}
		}
	}
	return false;
}

and in grid actor.cpp

void AGridActor::SetDynamicMaterialInstance(UMaterialInstanceDynamic* InMaterial, FLinearColor InColor)
{
	GridActorMeshComponent->GetStaticMesh()->SetMaterial(0, InMaterial);
	Material_Dyn = InMaterial;
	FLinearColor Color = InColor;
	Material_Dyn->SetVectorParameterValue(TEXT("Color"), Color);
}

for some reason, when i change color of one cell, it changes the color of all cells. why?

[ConstableCatnip (WeirdOne84)]

Solution. All new objects were using the same pointer to the same static mesh asset. To resolve this problem, i used DuplicateObject and saved that pointer to the gridactor static mesh. now each cell changes color independently.

[ConstableCatnip (WeirdOne84)]

updated code for reference
GridActorMeshComponent = CreateDefaultSubobject(“GridActorMeshComponent”);
auto TheCube = ConstructorHelpers::FObjectFinder(TEXT(“StaticMesh’/Engine/BasicShapes/Cube.Cube’”));

if (TheCube.Object)
{
if (UWorld* ThisWorld = GetWorld())
{
UStaticMesh* MyCube = DuplicateObject(TheCube.Object, this);
GridActorMeshComponent->SetStaticMesh(MyCube);
GridActorMeshComponent->SetWorldScale3D(FVector(.5));
}
}