Grid Placement System
Core System
PlacementHelper

PlacementHelper

The PlacementHelper is a simplified Blueprint Function Library that provides an easy-to-use interface for the Grid Placement System. It handles all the complex setup and management automatically, making it perfect for rapid prototyping and simple placement scenarios.

Overview

PlacementHelper wraps the full Grid Placement System functionality into simple static functions that can be called from anywhere in your project. It automatically manages the PlacementSystemComponent and PlacementObjectRegistry behind the scenes.

Key Benefits

  • ✅ Simple Setup - Just one function call to initialize everything
  • ✅ No Component Management - Handles component lifecycle automatically
  • ✅ Global Access - Static functions callable from any Blueprint or C++
  • ✅ Runtime Management - Add/remove objects dynamically during gameplay
  • ✅ UI Friendly - Perfect for inventory systems and object selection menus
  • ✅ Beginner Friendly - Minimal learning curve compared to full component system

Quick Start Guide

1. Initialize the System

Call this once in your Player Pawn's BeginPlay event:

// Blueprint: Event BeginPlay
PlacementHelper::InitializePlacementSystem(this);

2. Register Your Objects

Register each object you want to be placeable:

PlacementHelper::RegisterObject(
    ChairClass,           // Actor Class
    "Wooden Chair",       // Display Name
    ChairIcon,           // Icon (optional)
    "Comfortable seating", // Description (optional)
    "Furniture"          // Category (optional)
);

3. Start Placing

Trigger placement from any UI button or input:

// When player clicks "Place Chair" button
PlacementHelper::StartPlacing(ChairClass);

Function Reference

Setup Functions

InitializePlacementSystem

UFUNCTION(BlueprintCallable, Category = "GPS Easy Setup")
static void InitializePlacementSystem(APawn* PlayerPawn);

Initializes the placement system on the specified PlayerPawn. This function:

  • Finds or creates the required components (PlacementSystemComponent, PlacementObjectRegistry)
  • Auto-connects the components together
  • Stores global references for other functions to use

Parameters:

  • PlayerPawn - The player pawn to add the placement system to

Example Usage:

// Call in BeginPlay
void AMyPlayerPawn::BeginPlay()
{
    Super::BeginPlay();
    UPlacementHelper::InitializePlacementSystem(this);
}

Registration Functions

RegisterObject

UFUNCTION(BlueprintCallable, Category = "GPS Easy Setup")
static bool RegisterObject(
    TSubclassOf<AActor> ActorClass,
    const FString& DisplayName = "",
    UTexture2D* Icon = nullptr,
    const FString& Description = "",
    const FString& Category = "General"
);

Registers an Actor class as placeable in the system.

Parameters:

  • ActorClass - The Actor class to make placeable (must implement IPlaceableObjectInterface)
  • DisplayName - Human-readable name (defaults to class name if empty)
  • Icon - Optional icon texture for UI display
  • Description - Optional description text
  • Category - Category for organization (defaults to "General")

Returns:

  • bool - true if registration was successful, false if failed

Example Usage:

// Register different furniture pieces
UPlacementHelper::RegisterObject(ChairClass, "Office Chair", ChairIcon, "Ergonomic office seating", "Furniture");
UPlacementHelper::RegisterObject(TableClass, "Wooden Table", TableIcon, "Solid oak dining table", "Furniture");
UPlacementHelper::RegisterObject(LampClass, "Desk Lamp", LampIcon, "Adjustable LED lamp", "Lighting");

Placement Functions

StartPlacing

UFUNCTION(BlueprintCallable, Category = "GPS Easy Setup")
static bool StartPlacing(TSubclassOf<AActor> ActorClass);

Starts the placement process for the specified object class.

Parameters:

  • ActorClass - The Actor class to place (must be registered first)

Returns:

  • bool - true if placement started successfully, false if failed

Example Usage:

// Start placement when UI button is clicked
void OnChairButtonClicked()
{
    bool bSuccess = UPlacementHelper::StartPlacing(ChairClass);
    if (!bSuccess)
    {
        UE_LOG(LogTemp, Warning, TEXT("Failed to start placing chair"));
    }
}

Management Functions

RemoveObject

UFUNCTION(BlueprintCallable, Category = "GPS Management")
static bool RemoveObject(TSubclassOf<AActor> ActorClass);

Removes a specific object class from the registry.

Parameters:

  • ActorClass - The Actor class to remove

Returns:

  • bool - true if object was found and removed, false if not found

Example Usage:

// Remove chair from available objects
bool bRemoved = UPlacementHelper::RemoveObject(ChairClass);
if (bRemoved)
{
    UE_LOG(LogTemp, Log, TEXT("Chair removed from placement system"));
}

RemoveObjectsByCategory

UFUNCTION(BlueprintCallable, Category = "GPS Management")
static int32 RemoveObjectsByCategory(const FString& Category);

Removes all objects from a specific category. Useful for DLC unloading or unlocking systems.

Parameters:

  • Category - The category name to remove

Returns:

  • int32 - Number of objects that were removed

Example Usage:

// Remove all DLC furniture when unloading DLC
int32 RemovedCount = UPlacementHelper::RemoveObjectsByCategory("DLC Furniture");
UE_LOG(LogTemp, Log, TEXT("Removed %d DLC objects"), RemovedCount);

ClearAllObjects

UFUNCTION(BlueprintCallable, Category = "GPS Management")
static void ClearAllObjects();

Removes all objects from the registry. Useful for level transitions or complete resets.

Example Usage:

// Clear everything when transitioning to new level
UPlacementHelper::ClearAllObjects();

State Check Functions

IsObjectRegistered

UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GPS Data")
static bool IsObjectRegistered(TSubclassOf<AActor> ActorClass);

Checks if a specific object class is currently registered.

Parameters:

  • ActorClass - The Actor class to check

Returns:

  • bool - true if the object is registered, false otherwise

Example Usage:

// Check before attempting to place
if (UPlacementHelper::IsObjectRegistered(ChairClass))
{
    UPlacementHelper::StartPlacing(ChairClass);
}
else
{
    UE_LOG(LogTemp, Warning, TEXT("Chair not registered!"));
}

Data Retrieval Functions

GetRegisteredObjects

UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GPS Data")
static TArray<FPlaceableObjectData> GetRegisteredObjects();

Returns all registered placeable objects. Perfect for populating UI lists.

Returns:

  • TArray<FPlaceableObjectData> - Array of all registered objects with their metadata

Example Usage:

// Populate a UI list with all available objects
TArray<FPlaceableObjectData> AllObjects = UPlacementHelper::GetRegisteredObjects();
for (const FPlaceableObjectData& ObjectData : AllObjects)
{
    CreateUIButton(ObjectData.DisplayName, ObjectData.Icon, ObjectData.ActorClass);
}

GetAllCategories

UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GPS Data")
static TArray<FString> GetAllCategories();

Returns all unique categories from registered objects.

Returns:

  • TArray<FString> - Array of category names

Example Usage:

// Create category filter dropdown
TArray<FString> Categories = UPlacementHelper::GetAllCategories();
for (const FString& Category : Categories)
{
    CategoryDropdown->AddOption(Category);
}

GetObjectCount

UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GPS Data")
static int32 GetObjectCount();

Returns the total number of registered objects.

Returns:

  • int32 - Total count of registered objects

Example Usage:

// Display object count in UI
int32 Count = UPlacementHelper::GetObjectCount();
CountLabel->SetText(FText::FromString(FString::Printf(TEXT("%d Objects Available"), Count)));

Complete Usage Examples

Basic Setup and Registration

// In your GameMode or PlayerPawn BeginPlay
void AMyGameMode::BeginPlay()
{
    Super::BeginPlay();
    
    // Step 1: Initialize the system
    APawn* PlayerPawn = GetWorld()->GetFirstPlayerController()->GetPawn();
    UPlacementHelper::InitializePlacementSystem(PlayerPawn);
    
    // Step 2: Register your objects
    RegisterAllPlaceableObjects();
}
 
void AMyGameMode::RegisterAllPlaceableObjects()
{
    // Furniture
    UPlacementHelper::RegisterObject(ChairClass, "Office Chair", ChairIcon, "Ergonomic office seating", "Furniture");
    UPlacementHelper::RegisterObject(DeskClass, "Work Desk", DeskIcon, "Spacious workspace", "Furniture");
    UPlacementHelper::RegisterObject(BookshelfClass, "Bookshelf", BookshelfIcon, "Storage for books", "Furniture");
    
    // Lighting
    UPlacementHelper::RegisterObject(DeskLampClass, "Desk Lamp", LampIcon, "Adjustable LED lamp", "Lighting");
    UPlacementHelper::RegisterObject(CeilingFanClass, "Ceiling Fan", FanIcon, "Cooling and air circulation", "Lighting");
    
    // Decorations
    UPlacementHelper::RegisterObject(PlantClass, "Office Plant", PlantIcon, "Green decoration", "Decorations");
    UPlacementHelper::RegisterObject(PictureClass, "Wall Picture", PictureIcon, "Decorative artwork", "Decorations");
}

UI Integration Example

// In your UI widget class
void UInventoryWidget::PopulateObjectList()
{
    ObjectListWidget->ClearChildren();
    
    TArray<FPlaceableObjectData> AllObjects = UPlacementHelper::GetRegisteredObjects();
    
    for (const FPlaceableObjectData& ObjectData : AllObjects)
    {
        // Create button widget
        UObjectButton* Button = CreateWidget<UObjectButton>(this, ObjectButtonClass);
        Button->SetObjectData(ObjectData);
        Button->OnClicked.AddDynamic(this, &UInventoryWidget::OnObjectButtonClicked);
        
        ObjectListWidget->AddChild(Button);
    }
}
 
void UInventoryWidget::OnObjectButtonClicked(TSubclassOf<AActor> ActorClass)
{
    bool bSuccess = UPlacementHelper::StartPlacing(ActorClass);
    
    if (bSuccess)
    {
        // Close inventory UI
        SetVisibility(ESlateVisibility::Hidden);
    }
    else
    {
        ShowErrorMessage("Failed to start placement");
    }
}

Category-Based Organization

void UBuildingWidget::CreateCategoryTabs()
{
    TArray<FString> Categories = UPlacementHelper::GetAllCategories();
    
    for (const FString& Category : Categories)
    {
        // Create tab for each category
        UWidget* Tab = CreateCategoryTab(Category);
        CategoryTabBox->AddChild(Tab);
    }
}
 
void UBuildingWidget::ShowCategory(const FString& CategoryName)
{
    ObjectGrid->ClearChildren();
    
    TArray<FPlaceableObjectData> AllObjects = UPlacementHelper::GetRegisteredObjects();
    
    for (const FPlaceableObjectData& ObjectData : AllObjects)
    {
        if (ObjectData.Category == CategoryName)
        {
            // Add to current category view
            AddObjectToGrid(ObjectData);
        }
    }
}

Dynamic Content Management

// DLC Loading System
void AContentManager::LoadFurniturePack()
{
    // Load object classes from asset bundle
    TArray<TSubclassOf<AActor>> FurnitureClasses = LoadFurnitureAssets();
    
    for (TSubclassOf<AActor> FurnitureClass : FurnitureClasses)
    {
        FString Name = GetLocalizedName(FurnitureClass);
        UTexture2D* Icon = GetObjectIcon(FurnitureClass);
        
        bool bSuccess = UPlacementHelper::RegisterObject(FurnitureClass, Name, Icon, "", "DLC Furniture");
        if (!bSuccess)
        {
            UE_LOG(LogTemp, Warning, TEXT("Failed to register DLC furniture: %s"), *Name);
        }
    }
    
    UE_LOG(LogTemp, Log, TEXT("Loaded furniture pack. Total objects: %d"), UPlacementHelper::GetObjectCount());
}
 
void AContentManager::UnloadFurniturePack()
{
    int32 RemovedCount = UPlacementHelper::RemoveObjectsByCategory("DLC Furniture");
    UE_LOG(LogTemp, Log, TEXT("Unloaded %d DLC furniture objects"), RemovedCount);
}

Inventory System Integration

// Unlock system based on player progress
void AProgressManager::CheckUnlocks()
{
    // Check if player unlocked advanced furniture
    if (PlayerLevel >= 10 && !UPlacementHelper::IsObjectRegistered(LuxuryChairClass))
    {
        UPlacementHelper::RegisterObject(LuxuryChairClass, "Luxury Chair", LuxuryChairIcon, "Premium leather seating", "Premium Furniture");
        ShowUnlockNotification("New furniture unlocked!");
    }
    
    // Remove basic furniture when player reaches expert level
    if (PlayerLevel >= 20)
    {
        int32 RemovedCount = UPlacementHelper::RemoveObjectsByCategory("Basic Furniture");
        if (RemovedCount > 0)
        {
            ShowMessage(FString::Printf(TEXT("Replaced %d basic items with advanced variants"), RemovedCount));
        }
    }
}

Search and Filter System

void UInventoryWidget::FilterObjects(const FString& SearchTerm, const FString& CategoryFilter)
{
    TArray<FPlaceableObjectData> AllObjects = UPlacementHelper::GetRegisteredObjects();
    TArray<FPlaceableObjectData> FilteredObjects;
    
    for (const FPlaceableObjectData& ObjectData : AllObjects)
    {
        bool bMatchesSearch = SearchTerm.IsEmpty() || 
                             ObjectData.DisplayName.Contains(SearchTerm) ||
                             ObjectData.Description.Contains(SearchTerm);
                             
        bool bMatchesCategory = CategoryFilter.IsEmpty() || 
                               CategoryFilter == "All" ||
                               ObjectData.Category == CategoryFilter;
                               
        if (bMatchesSearch && bMatchesCategory)
        {
            FilteredObjects.Add(ObjectData);
        }
    }
    
    UpdateObjectList(FilteredObjects);
}

Comparison: PlacementHelper vs Full Component System

AspectPlacementHelperFull Component System
Setup ComplexitySingle function callManual component setup
Control LevelSimplified APIFull control and customization
Global Access✅ Anywhere in project❌ Only from component owner
UI Integration✅ Perfect for menus❌ Requires more wiring
Runtime Management✅ Easy add/remove✅ Full control
Event System❌ Limited events✅ Comprehensive events
Customization❌ Limited✅ Extensive
Best ForPrototypes, simple gamesComplex, customized systems

Error Handling

PlacementHelper includes built-in error handling and validation:

// Example with comprehensive error checking
bool bSystemInitialized = false;
 
void InitializeWithErrorHandling(APawn* PlayerPawn)
{
    if (!PlayerPawn)
    {
        UE_LOG(LogTemp, Error, TEXT("PlayerPawn is null!"));
        return;
    }
    
    UPlacementHelper::InitializePlacementSystem(PlayerPawn);
    
    // Verify initialization by registering a test object
    bool bTestRegistration = UPlacementHelper::RegisterObject(TestActorClass, "Test Object");
    if (!bTestRegistration)
    {
        UE_LOG(LogTemp, Error, TEXT("Failed to register test object - system may not be initialized properly"));
        return;
    }
    
    // Clean up test object
    UPlacementHelper::RemoveObject(TestActorClass);
    
    bSystemInitialized = true;
    UE_LOG(LogTemp, Log, TEXT("PlacementHelper initialized successfully"));
}
 
void SafePlacement(TSubclassOf<AActor> ActorClass)
{
    if (!bSystemInitialized)
    {
        UE_LOG(LogTemp, Error, TEXT("PlacementHelper not initialized!"));
        return;
    }
    
    if (!ActorClass)
    {
        UE_LOG(LogTemp, Error, TEXT("ActorClass is null!"));
        return;
    }
    
    if (!UPlacementHelper::IsObjectRegistered(ActorClass))
    {
        UE_LOG(LogTemp, Warning, TEXT("ActorClass not registered: %s"), *ActorClass->GetName());
        return;
    }
    
    bool bSuccess = UPlacementHelper::StartPlacing(ActorClass);
    if (!bSuccess)
    {
        UE_LOG(LogTemp, Warning, TEXT("Failed to start placement for: %s"), *ActorClass->GetName());
    }
}

Performance Considerations

Best Practices

  1. Batch Registration:
// Register objects in batches during loading screens
void RegisterObjectsBatch()
{
    // Disable UI updates during batch registration
    bUpdatingRegistry = true;
    
    // Register all objects
    for (const auto& ObjectData : ObjectsToRegister)
    {
        UPlacementHelper::RegisterObject(ObjectData.ActorClass, ObjectData.DisplayName, ObjectData.Icon, ObjectData.Description, ObjectData.Category);
    }
    
    // Re-enable UI updates and refresh
    bUpdatingRegistry = false;
    RefreshUI();
}
  1. Conditional Registration:
// Only register objects when needed
void RegisterContextualObjects(EGameMode GameMode)
{
    switch (GameMode)
    {
        case EGameMode::Building:
            RegisterBuildingObjects();
            break;
        case EGameMode::Decorating:
            RegisterDecorationObjects();
            break;
        case EGameMode::Landscaping:
            RegisterLandscapeObjects();
            break;
    }
}
  1. Memory Management:
// Clean up when transitioning between levels
void OnLevelTransition()
{
    // Clear all registered objects to free memory
    UPlacementHelper::ClearAllObjects();
    
    // Force garbage collection
    GetWorld()->ForceGarbageCollection(true);
}

Troubleshooting

Common Issues

"Failed to start placement"

  • Ensure InitializePlacementSystem() was called first
  • Check that the ActorClass is registered using IsObjectRegistered()
  • Verify the ActorClass implements IPlaceableObjectInterface
  • Check console logs for initialization errors

"Object registration failed"

  • Verify ActorClass is not null
  • Ensure ActorClass implements IPlaceableObjectInterface
  • Check if object is already registered (duplicates are rejected)
  • Verify PlacementHelper system is initialized

"No objects in list"

  • Make sure RegisterObject() is called after InitializePlacementSystem()
  • Check that registration calls are not in a constructor or before BeginPlay
  • Verify GetRegisteredObjects() is called after objects are registered
  • Use GetObjectCount() to debug registration state

"Object not placing"

  • Ensure level surfaces are tagged correctly ("Floor", "Wall", "Roof")
  • Check that the object's PlacementType matches available surfaces
  • Verify placement location isn't blocked by other objects
  • Enable debug mode in PlacementSystemComponent to see collision visualization

"Categories not showing"

  • Check for typos in category names (case-sensitive)
  • Verify objects actually have category assignments
  • Use GetAllCategories() to debug available categories

Validation Utilities

// Validate all registered objects
bool ValidateRegisteredObjects()
{
    TArray<FPlaceableObjectData> AllObjects = UPlacementHelper::GetRegisteredObjects();
    bool bAllValid = true;
    
    for (const FPlaceableObjectData& ObjectData : AllObjects)
    {
        if (!ObjectData.ActorClass)
        {
            UE_LOG(LogTemp, Error, TEXT("Object '%s' has null ActorClass"), *ObjectData.DisplayName);
            bAllValid = false;
        }
        else if (!ObjectData.ActorClass->ImplementsInterface(UPlaceableObjectInterface::StaticClass()))
        {
            UE_LOG(LogTemp, Error, TEXT("Object '%s' doesn't implement IPlaceableObjectInterface"), *ObjectData.DisplayName);
            bAllValid = false;
        }
        
        if (ObjectData.DisplayName.IsEmpty())
        {
            UE_LOG(LogTemp, Warning, TEXT("Object has empty DisplayName"));
        }
    }
    
    return bAllValid;
}

PlacementHelper provides a robust, user-friendly interface for the Grid Placement System with comprehensive error handling, runtime management capabilities, and extensive debugging support.

OverviewPlacementObjectRegistry