Disable Chaos Field System Interaction with Cloth - C++ Implementation

Development Programming & Scripting C++
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1

Greetings, I’m currently using the Chaos destruction system with the field system component in order to activate the destruction.
It is all working correctly, however, when activating a field system the cape in my character (which is made with Chaos Cloth) gets bugged and becomes frozen.

The working field system is currently using the following code:

void AExplosionFieldSystemActor::Explode()
{
	UFieldSystemComponent* FSystemComponent = GetFieldSystemComponent();

	if (FieldSystemComponent)
	{
		float SphereRadius = ExplosionArea->GetScaledSphereRadius();
		FVector CenterPosition = ExplosionArea->GetComponentLocation();

		// Strain Field
		FieldSystemComponent->ApplyStrainField(true, CenterPosition, SphereRadius, StrainMagnitude, 1);

		// Linear Velocity Field
		FieldSystemComponent->ApplyUniformVectorFalloffForce(true, CenterPosition, GetActorForwardVector(), SphereRadius, VelocityMagnitude);

		// Delete after explosion to avoid physics inconsistencies
		Destroy();
	}
}

But this doesn’t allow to use the MetaData filter seen here: https://docs.unrealengine.com/5.0/en-US/API/Runtime/FieldSystemEngine/Field/UFieldSystemComponent/ in various functions.

With this, I tried to use the ApplyPhysicsField() function since it does allow to setup the filter.
However, using the field system this way doesn’t work, Chaos destruction isn’t activated. The implementation looks like this:

AExplosionFieldSystemActor::AExplosionFieldSystemActor()
{
        // ............. Other vars being set in constructor

	MetaData = CreateDefaultSubobject<UFieldSystemMetaDataFilter>(TEXT("MetaData"));
	MetaData->SetMetaDataFilterType(EFieldFilterType::Field_Filter_All, EFieldObjectType::Field_Object_Cloth, EFieldPositionType::Field_Position_CenterOfMass);

	RadialFalloff = CreateDefaultSubobject<URadialFalloff>(TEXT("RadialFalloff"));

	UniformVector = CreateDefaultSubobject<UUniformVector>(TEXT("UniformVector"));
}

void AExplosionFieldSystemActor::Explode()
{
	UFieldSystemComponent* FSystemComponent = GetFieldSystemComponent();

	if (FieldSystemComponent)
	{
		// Strain Field
		DetermineRadialFalloff();
		FieldSystemComponent->ApplyPhysicsField(true, EFieldPhysicsType::Field_ExternalClusterStrain, MetaData, RadialFalloff);

		// Linear Velocity Field
		DetermineUniformVector();
		FieldSystemComponent->ApplyPhysicsField(true, EFieldPhysicsType::Field_LinearVelocity, MetaData, UniformVector);

		// Delete after explosion to avoid physics inconsistencies
		Destroy();
	}
}

void AExplosionFieldSystemActor::DetermineRadialFalloff()
{
	float SphereRadius = ExplosionArea->GetScaledSphereRadius();
	FVector CenterPosition = ExplosionArea->GetComponentLocation();

	RadialFalloff->SetRadialFalloff(StrainMagnitude, 0.0f, 1.0f, 0.0f, SphereRadius, CenterPosition, EFieldFalloffType::Field_FallOff_None);
}

void AExplosionFieldSystemActor::DetermineUniformVector()
{
	UniformVector->SetUniformVector(VelocityMagnitude, GetActorForwardVector());
}

Any ideas on how to make this work? Everything is set according to the documentation, but it simply doesn’t work, not even setting the filter to affect all makes it work.

Thanks for any tips.

2

Hi, did you manage to find a way around this issue?
I have the exact same thing happening in our project.

One way I tried to solve this is by specifying custom Chaos Solvers in the Supported Solvers property of the Field System Component, which would mean that the default cloth solver would not be affected.
This did not work.

My work around atm is to apply linear forces only on specific Geometry Collections, however this isn’t very elegant.