[UE4 code snippets] Snippets for some simple tasks in UE4 #tags: UE4, unrealcv

basic_types.cpp

FString
FName
// How to convert between them

draw_center.cpp

for (TActorIterator<AActor> ActorItr(World); ActorItr; ++ActorItr)
{
  AActor* Actor = *ActorItr;
  FVector WorldLocation = Actor->GetActorLocation();
  FVector2D ScreenLocation;

  APlayerController* PlayerController = World->GetFirstPlayerController();
  PlayerController->ProjectWorldLocationToScreen(WorldLocation, ScreenLocation);

  // AHUD *HUD = UGameplayStatics::GetPlayerController(Player, 0)->GetHUD();
  AHUD *HUD = PlayerController->GetHUD();

  // Check if this position is occluded, if yes, mark it with a different color.

  FVector Start = PlayerPawn->GetActorLocation();
  FVector End = Actor->GetActorLocation();

  FHitResult HitResult;
  // World->LineTraceSingleByChannel(HitResult, Start, End, ECollisionChannel::ECC_Pawn);
  FCollisionObjectQueryParams ObjectQueryParams(FCollisionObjectQueryParams::AllObjects);
  FCollisionQueryParams QueryParams = FCollisionQueryParams::DefaultQueryParam;
  QueryParams.AddIgnoredActor(PlayerPawn);

  World->LineTraceSingleByObjectType(HitResult, Start, End, ObjectQueryParams, QueryParams);

  if (HitResult.GetActor() == Actor)
  {
    HUD->DrawRect(FLinearColor::Green, ScreenLocation.X, ScreenLocation.Y, 5, 5);
  }
  else
  {
    AActor* HitActor = HitResult.GetActor();
    HUD->DrawRect(FLinearColor::Red, ScreenLocation.X, ScreenLocation.Y, 5, 5);
  }
}

draw_debug_3d.cpp

#include "DrawDebugHelpers.h" // This is written by Rama and include in UE4 officially now
// The wiki page for this helper file is [here](https://wiki.unrealengine.com/Draw_3D_Debug_Points,_Lines,_and_Spheres:_Visualize_Your_Algorithm_in_Action)
DrawDebugPoint(World, ActorLocation + Keypoint, 10, FColor::Red, true, 10);

get_actor.cpp

FString ModelId = TEXT("");
UWorld* World = ;
for (TActorIterator<AActor> ActorItr(World); ActorItr; ++ActorItr)
{
    AActor* Actor = *ActorItr;
    if (Actor->GetName() == ModelId)
    {
        break;
    }
}

get_id.cpp

// There are two types of ID in UE4. One is the editor label, the other is the id.
// The editor label is only available in editor and not available in a game binary.

iterate_actors.cpp

void AShaderPluginDemoCharacter::ListAllActors()
{
	ULevel *Level = GetLevel();

	for (auto Actor : Level->Actors)
	{
		UE_LOG(LogTemp, Warning, TEXT("%s"), *Actor->GetActorLabel());
	}
}

log.cpp

// Print log information to UE4 output console and the visual studio output console.
// Be careful with Warning and Error level message, these messages will prevent the packaging of a game.

UE_LOG(LogUnrealCV, Log, TEXT("The connection is gracefully closed by the client."));
// Useful Log levels: Log, Warning, Error.

// You can also create a new log category
DEFINE_LOG_CATEGORY(LogUnrealCV);

UE4 code snippets.md

Useful snippets for some UE4 tasks.

• draw_center.cpp How to draw actor center
• get_actor.cpp How to get an actor using its id
• draw_debug_3d.cpp How to draw 3D debug points