RVO Avoidance

Types

UAvoidanceManager

Created in UWorld::InitWorld, use UWorld::GetAvoidanceManager to get it. The class can be changed in the Engine.ini file.

# Default
[/Script/Engine.Engine]
AvoidanceManagerClassName=/Script/Engine.AvoidanceManager

More

More about AvoidanceWeight

As described at UAvoidanceManager::RegisterMovementComponent: “When avoiding each other, actors divert course in proportion to their relative weights. Range is 0.0 to 1.0. Special: at 1.0, actor will not divert course at all”

IRVOAvoidanceInterface

Interface for objects that want to perform RVO avoidance. See UCharacterMovementComponent and UWheeledVehicleMovementComponent for example implementations.

Miscs

FNavAvoidanceData

There seems to be one instance of this struct per managed IRVOAvoidanceInterface (See UAvoidanceManager::RegisterMovementComponent and UAvoidanceManager::UpdateRVO). Stored in AvoidanceObjects on the UAvoidanceManager.

Most of its variables are initialized from the getters of the IRVOAvoidanceInterface interface.

FNavAvoidanceMask

FVelocityAvoidanceCone

Usages

Character Movement Component

To see an example of implementation in the engine lest look the UCharacterMovementComponent. It has a bUseRVOAvoidance variable (Note: RVO Avoidance only runs on the server).

Inside UCharacterMovementComponent::SetUpdatedComponent if bUseRVOAvoidance is true we get the avoidance manager and call UAvoidanceManager::RegisterMovementComponent.

Inside UCharacterMovementComponent::TickComponent if bUseRVOAvoidance is true UCharacterMovementComponent::UpdateDefaultAvoidance is called. It will call UAvoidanceManager::UpdateRVO if bWasAvoidanceUpdated is false as well as UCharacterMovementComponent::SetAvoidanceVelocityLock.

Inside UCharacterMovementComponent::CalcVelocity if bUseRVOAvoidance is true UCharacterMovementComponent::CalcAvoidanceVelocity is called. Unless we are locked (see AvoidanceLockTimer) we get our new velocity with UAvoidanceManager::GetAvoidanceVelocityForComponent. Then if bUseRVOPostProcess is true we call UCharacterMovementComponent::PostProcessAvoidanceVelocity which is only meant to be used by subclasses. We then call UCharacterMovementComponent::SetAvoidanceVelocityLock, this is how the CMC handles overwriting whatever velocity was calculated, the important part is to look the duration of the lock. It will call UAvoidanceManager::UpdateRVO. This also sets bWasAvoidanceUpdated to true.

How it works

From the usage of the UCharacterMovementComponent the main functions seem to to register the component, call update each frame and get the velocity when needed.

UAvoidanceManager::GetAvoidanceVelocityForComponent calls UAvoidanceManager::GetAvoidanceVelocity_Internal which does the path for RVO avoidance. The ignored UID is the id of the object that we want to update.

UAvoidanceManager::UpdateRVO calls UAvoidanceManager::UpdateRVO_Internal which updates the internal FNavAvoidanceData data.

Debug and Commands

Console Commands:

• AvoidanceDisplayAll (Calls UAvoidanceManager::HandleToggleDebugAll)
• AvoidanceSystemToggle (Calls UAvoidanceManager::HandleToggleAvoidance)

For more precise (but manual) debugging see UAvoidanceManager::AvoidanceDebugForUID.