C++ UNavigationSystem::TestPathSync方法代码示例

bool UNavigationComponent::GeneratePathTo(const FVector& GoalLocation, TSharedPtr<const FNavigationQueryFilter> QueryFilter)
{
	if (GetWorld() == NULL || GetWorld()->GetNavigationSystem() == NULL || GetOuter() == NULL)
	{
		return false;
	}

	// Make sure we're trying to path to the closest valid location TO that location rather than the absolute location.
	// After talking with Steve P., if we need to ever allow pathing WITHOUT projecting to nav-mesh, it will probably be
	// best to do so using a flag while keeping this as the default behavior.  NOTE:` If any changes to this behavior
	// are made, you should search for other places in UNavigationComponent using NavMeshGoalLocation and make sure the
	// behavior remains consistent.
	
	// make sure that nav data is updated
	GetNavData();

	const FNavAgentProperties* NavAgentProps = MyNavAgent ? MyNavAgent->GetNavAgentProperties() : NULL;
	if (NavAgentProps != NULL)
	{
		FVector NavMeshGoalLocation;

#if ENABLE_VISUAL_LOG
		UE_VLOG_LOCATION(GetOwner(), GoalLocation, 34, FColor(0,127,14), TEXT("GoalLocation"));
		const FVector ProjectionExtent = MyNavData ? MyNavData->GetDefaultQueryExtent() : FVector(DEFAULT_NAV_QUERY_EXTENT_HORIZONTAL, DEFAULT_NAV_QUERY_EXTENT_HORIZONTAL, DEFAULT_NAV_QUERY_EXTENT_VERTICAL);
		UE_VLOG_BOX(GetOwner(), FBox(GoalLocation - ProjectionExtent, GoalLocation + ProjectionExtent), FColor::Green, TEXT_EMPTY);
#endif

		if (ProjectPointToNavigation(GoalLocation, NavMeshGoalLocation) == QuerySuccess)
		{
			UE_VLOG_SEGMENT(GetOwner(), GoalLocation, NavMeshGoalLocation, FColor::Blue, TEXT_EMPTY);
			UE_VLOG_LOCATION(GetOwner(), NavMeshGoalLocation, 34, FColor::Blue, TEXT_EMPTY);
			
			UNavigationSystem* NavSys = GetWorld()->GetNavigationSystem();
			FPathFindingQuery Query(MyNavData, MyNavAgent->GetNavAgentLocation(), NavMeshGoalLocation, QueryFilter);

			const EPathFindingMode::Type Mode = bDoHierarchicalPathfinding ? EPathFindingMode::Hierarchical : EPathFindingMode::Regular;
			FPathFindingResult Result = NavSys->FindPathSync(*MyNavAgent->GetNavAgentProperties(), Query, Mode);

			// try reversing direction
			if (bSearchFromGoalWhenOutOfNodes && !bDoHierarchicalPathfinding &&
				Result.Path.IsValid() && Result.Path->DidSearchReachedLimit())
			{
				// quick check if path exists
				bool bPathExists = false;
				{
					DECLARE_SCOPE_CYCLE_COUNTER(TEXT("Pathfinding: HPA* test time"), STAT_Navigation_PathVerifyTime, STATGROUP_Navigation);
					bPathExists = NavSys->TestPathSync(Query, EPathFindingMode::Hierarchical);
				}

				UE_VLOG(GetOwner(), LogNavigation, Log, TEXT("GeneratePathTo: out of nodes, HPA* path: %s"),
					bPathExists ? TEXT("exists, trying reversed search") : TEXT("doesn't exist"));

				// reverse search
				if (bPathExists)
				{
					DECLARE_SCOPE_CYCLE_COUNTER(TEXT("Pathfinding: reversed test time"), STAT_Navigation_PathReverseTime, STATGROUP_Navigation);

					TSharedPtr<FNavigationQueryFilter> Filter = QueryFilter.IsValid() ? QueryFilter->GetCopy() : MyNavData->GetDefaultQueryFilter()->GetCopy();					
					Filter->SetBacktrackingEnabled(true);

					FPathFindingQuery ReversedQuery(MyNavData, Query.EndLocation, Query.StartLocation, Filter);
					Result = NavSys->FindPathSync(*MyNavAgent->GetNavAgentProperties(), Query, Mode);
				}
			}

			if (Result.IsSuccessful() || Result.IsPartial())
			{
				CurrentGoal = NavMeshGoalLocation;
				SetPath(Result.Path);

				if (IsFollowing() == true)
				{
					// make sure ticking is enabled (and it shouldn't be enabled before _first_ async path finding)
					SetComponentTickEnabledAsync(true);
				}

				NotifyPathUpdate();
				return true;
			}
			else
			{
				UE_VLOG(GetOwner(), LogNavigation, Display, TEXT("Failed to generate path to destination"));
			}
		}
		else
		{
			UE_VLOG(GetOwner(), LogNavigation, Display, TEXT("Destination not on navmesh (and nowhere near!)"));
		}
	}
	else
	{
		UE_VLOG(GetOwner(), LogNavigation, Display, TEXT("UNavigationComponent::GeneratePathTo: NavAgentProps == NULL (Probably Pawn died)"));
	}

	return false;
}