How can I change the values of a Dynamic Material in C++?

Development Rendering
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1

So I am trying to get a dynamic material to render properly but when I call SetScalarParameterValue, it has no effect on the material. How can I get the material to change based on the values that are passed in?

Here is the code that I have…

UCircualrUIDecalComponent::UCircualrUIDecalComponent(const class FObjectInitializer& PCIP) : Super(PCIP), ObjectFinderBaseMaterial(TEXT("/Game/UIStuff/NewUI/circUI.circUI")) 
{
	if (ObjectFinderBaseMaterial.Succeeded()) 
	{
		DynamicMaterial = UMaterialInstanceDynamic::Create(ObjectFinderBaseMaterial.Object, this);
		SetMaterial(0, DynamicMaterial);
	}

	DynamicMaterial->SetScalarParameterValue("health", health);
	DynamicMaterial->SetScalarParameterValue("armor", armor);
	DynamicMaterial->SetScalarParameterValue("XP", XP);
	DynamicMaterial->SetScalarParameterValue("passiveAbil", passAbil);
}
2

Hi DisastrousEvans,

I am a fairly inexperienced coder so prepare a grain of salt to go with my response.

I think it is unusual to set up an MID inside of the class constructor like that. I have never seen it done. I asked one of our rendering guys and he agreed; he suggested that any values there will not be initialized or will get stomped by serialization. Can you try creating the MID by some function that is triggered after postbeginplay?

3

After tooling around with this myself, this is the best solution I could come up with this problem.

I am new to Unreal and fairly new to C++ code, so take this advice as you wish:

RootAnnexActor.cpp

ARootAnnexActor::ARootAnnexActor() 
{ 	
    ...

    // Add the root to hold the bounds of this Annex 	
    AnnexBoundsMeshComponent = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Bounds Mesh Component")); 	
    AnnexBoundsMeshComponent->AttachParent = RootComponent; 
}

void ARootAnnexActor::OnConstruction(const FTransform &Transform) 
{ 	
    Super::OnConstruction(Transform); 	
    // Set the DynamicMaterial so we can Edit it 	
    BoundsDynamicMaterial = AnnexBoundsMeshComponent->CreateDynamicMaterialInstance(0); 
}

In RootAnnexActor.h

// Add Dynamic Material
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = StaticMesh)
UMaterialInstanceDynamic* BoundsDynamicMaterial;

Later in Code I am change values with or even in OnConstruction if you really wanted to:

BoundsDynamicMaterial->SetVectorParameterValue(TEXT("BaseColor"), FLinearColor::Green);