praca_magisterska/games/unreal/tutorial/part-7-cpp-create-ui.md

Part 7 (C++): Create UI

← Previous: Part 6 (C++) - Create Game Director | Back to Index | Next: Part 8 (C++) - Create Game Mode →

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Overview

For UI, we use Widget Blueprints for visual layout (drag-and-drop is better for UI design), but bind to C++ properties for data.

Time: ~15 minutes

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Step 7.1: Create Widget Blueprint

1. Content Browser → UI folder
2. Right-click → User Interface → Widget Blueprint
3. Name: WBP_HUD
4. Double-click to open Widget Designer

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Step 7.2: Design HUD Layout

In Widget Designer:

1. Add a Canvas Panel (if not already present):

   • Drag Canvas Panel from Palette → Panel onto the root
   • This is your container for all UI elements

2. Add Text blocks (drag each from Palette → Common onto the Canvas Panel):

   • Drag a Text widget → rename to txt_Score (click on it in Hierarchy, press F2)
   • Drag another Text widget → rename to txt_Lives
   • Drag another Text widget → rename to txt_Timer

3. Position them (select each and set in Details panel → Slot):

   • txt_Score: Position X=20, Y=20
   • txt_Lives: Position X=20, Y=50
   • txt_Timer: Position X=20, Y=80

4. Style each text (select in Hierarchy, edit in Details panel):

   • Font → Size: 24
   • Color and Opacity: White
   • Set default Text content:
     • txt_Score: Score: 0
     • txt_Lives: Lives: 3
     • txt_Timer: Time: 300

5. Important: Set "Is Variable" for each text block:

   • Select txt_Score in Hierarchy
   • In Details panel, check Is Variable ✓
   • Repeat for txt_Lives and txt_Timer
   • (This allows C++ to find them by name)

6. Compile and Save

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Step 7.3: Create HUD Manager C++ Class

We'll create a simple C++ class to update the UI.

1. Tools → New C++ Class → Actor → Name: STGHUDManager
2. Wait for compilation

STGHUDManager.h

Replace content with:

⚠️ IMPORTANT: Replace YOURPROJECTNAME_API with your actual project's API macro (e.g., BULLETHELLCPP_API).

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "STGHUDManager.generated.h"

UCLASS()
class YOURPROJECTNAME_API ASTGHUDManager : public AActor
{
    GENERATED_BODY()
    
public:    
    ASTGHUDManager();

protected:
    virtual void BeginPlay() override;

public:    
    virtual void Tick(float DeltaTime) override;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UI")
    TSubclassOf<class UUserWidget> HUDWidgetClass;

    UFUNCTION(BlueprintCallable, Category = "UI")
    void UpdateScore(int32 NewScore);

    UFUNCTION(BlueprintCallable, Category = "UI")
    void UpdateLives(int32 NewLives);

    UFUNCTION(BlueprintCallable, Category = "UI")
    void UpdateTimer(float TimeRemaining);

private:
    class UUserWidget* HUDWidget;
};

STGHUDManager.cpp:

#include "STGHUDManager.h"
#include "Blueprint/UserWidget.h"
#include "Components/TextBlock.h"

ASTGHUDManager::ASTGHUDManager()
{
    PrimaryActorTick.bCanEverTick = true;
}

void ASTGHUDManager::BeginPlay()
{
    Super::BeginPlay();
    
    if (HUDWidgetClass)
    {
        HUDWidget = CreateWidget<UUserWidget>(GetWorld(), HUDWidgetClass);
        if (HUDWidget)
        {
            HUDWidget->AddToViewport();
        }
    }
}

void ASTGHUDManager::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
}

void ASTGHUDManager::UpdateScore(int32 NewScore)
{
    if (HUDWidget)
    {
        UTextBlock* ScoreText = Cast<UTextBlock>(HUDWidget->GetWidgetFromName(TEXT("txt_Score")));
        if (ScoreText)
        {
            ScoreText->SetText(FText::Format(FText::FromString("Score: {0}"), NewScore));
        }
    }
}

void ASTGHUDManager::UpdateLives(int32 NewLives)
{
    if (HUDWidget)
    {
        UTextBlock* LivesText = Cast<UTextBlock>(HUDWidget->GetWidgetFromName(TEXT("txt_Lives")));
        if (LivesText)
        {
            LivesText->SetText(FText::Format(FText::FromString("Lives: {0}"), NewLives));
        }
    }
}

void ASTGHUDManager::UpdateTimer(float TimeRemaining)
{
    if (HUDWidget)
    {
        UTextBlock* TimerText = Cast<UTextBlock>(HUDWidget->GetWidgetFromName(TEXT("txt_Timer")));
        if (TimerText)
        {
            int32 Seconds = FMath::CeilToInt(TimeRemaining);
            TimerText->SetText(FText::Format(FText::FromString("Time: {0}s"), Seconds));
        }
    }
}

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Step 7.4: Integrate HUD with Game

1. Place STGHUDManager in level

2. Select it, in Details panel:

   • Set HUD Widget Class → WBP_HUD

3. Update STGGameDirector to update timer:

void ASTGGameDirector::Tick(float DeltaTime)
{
    // ... existing code ...
    
    // Update HUD
    TArray<AActor*> FoundManagers;
    UGameplayStatics::GetAllActorsOfClass(GetWorld(), ASTGHUDManager::StaticClass(), FoundManagers);
    if (FoundManagers.Num() > 0)
    {
        ASTGHUDManager* HUDMgr = Cast<ASTGHUDManager>(FoundManagers[0]);
        if (HUDMgr)
        {
            HUDMgr->UpdateTimer(GameDuration - ElapsedTime);
        }
    }
}

4. Update STGPawn to update score/lives when they change:

First, add the include at the top of STGPawn.cpp:

#include "STGHUDManager.h"

Then create a helper function to find and update the HUD. Add this private method to STGPawn.h:

private:
    void UpdateHUD();

Add the implementation in STGPawn.cpp:

void ASTGPawn::UpdateHUD()
{
    TArray<AActor*> FoundManagers;
    UGameplayStatics::GetAllActorsOfClass(GetWorld(), ASTGHUDManager::StaticClass(), FoundManagers);
    if (FoundManagers.Num() > 0)
    {
        ASTGHUDManager* HUDMgr = Cast<ASTGHUDManager>(FoundManagers[0]);
        if (HUDMgr)
        {
            HUDMgr->UpdateScore(Score);
            HUDMgr->UpdateLives(CurrentLives);
        }
    }
}

Call UpdateHUD() in these places:

In AddScore():

void ASTGPawn::AddScore(int32 Points)
{
    Score += Points;
    UpdateHUD();
}

In TakeHit() (after updating CurrentLives):

void ASTGPawn::TakeHit(int32 Damage)
{
    // ... existing damage code ...
    CurrentLives = FMath::Clamp(CurrentLives - Damage, 0, MaxLives);
    UpdateHUD();  // Add this line
    // ... rest of function ...
}

In BeginPlay() (to initialize HUD with starting values):

void ASTGPawn::BeginPlay()
{
    Super::BeginPlay();
    CurrentLives = MaxLives;
    
    // ... existing input setup code ...
    
    // Initialize HUD
    UpdateHUD();
}

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Step 7.5: Test UI

Press Play

Expected Result:

In Play Mode:

• ✅ UI appears in top-left corner
• ✅ "Score: 0", "Lives: 3", "Time: 300" displayed
• ✅ Timer counts down from 300
• ✅ Score increases when enemies are destroyed
• ✅ Lives decrease when player is hit
• ✅ Text is readable (white on dark background)

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← Previous: Part 6 (C++) - Create Game Director | Back to Index | Next: Part 8 (C++) - Create Game Mode →