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Wind and External Forces

This guide explains how to set up wind and external forces in KawaiiPhysics.

Wind System​

Can integrate with Unreal Engine's wind system.

Enabling​

UPROPERTY()
bool bEnableWind = false;

Wind Scale​

Adjusts the influence of wind.

UPROPERTY()
float WindScale = 1.0f;

Wind Directional Source Support​

Version Info

Added in v1.17.0

Now supports Unreal Engine's Wind Directional Source. Automatically affected by wind placed in level.

Setup:

  1. Place Wind Directional Source in level
  2. Enable bEnableWind in KawaiiPhysics node
  3. Adjust influence with WindScale

Wind Directional Source intensity and direction are reflected to KawaiiPhysics physics bones.

Custom External Forces​

Apply force in any direction.

Setting from Blueprint​

// Apply force forward
SetExternalForce(GetActorForwardVector() * 100.0f);

Use Cases​

  • Wind pressure during jumps
  • Explosion knockback
  • Underwater resistance

Gravity​

Default Gravity​

UPROPERTY()
FVector Gravity = FVector::ZeroVector;

Custom Gravity​

Different gravity can be applied to specific bones.

Gravity direction examples:

  ↓ (0, 0, -980)      → (980, 0, 0)      ↑ (0, 0, 980)
  Default gravity      Sideways gravity    Upward gravity
  (hair hangs down)    (hair flows sideways) (hair stands up)

Force Composition​

Multiple forces are added together and applied.

Final Force = Gravity + Wind + ExternalForce

Dynamic Control​

Forces can be changed in real-time during gameplay.

// Vary wind in Event Tick
void AMyCharacter::Tick(float DeltaTime)
{
    // Vary wind strength with sine wave
    float WindStrength = FMath::Sin(GetWorld()->GetTimeSeconds()) * 50.0f;
    KawaiiPhysicsComponent->SetExternalForce(FVector(WindStrength, 0, 0));
}

For more details, see Runtime Control.