Converting Unity C# Scripts to Unreal Engine C++: A Comprehensive Guide (2024)

The worlds of Unity and Unreal Engine, though similar in their quest to offer top-notch game development tools, differ significantly in their foundational architecture. As a result, moving between these two platforms is far from straightforward, especially when converting Unity C# scripts to Unreal Engine C++.

This article delves into a step-by-step guide for such a transition, giving you the insights needed to bring your Unity project ideas into the Unreal environment.

1. The Foundational Difference

Before diving into the conversion process, it’s essential to grasp the fundamental differences between Unity and Unreal Engine:

2. Preparing for Conversion

Setting up an Unreal Engine C++ class:

1. Start by creating an appropriate C++ class within your Unreal project. For scripts derived from MonoBehaviour in Unity, consider beginning with AActor or UObject in Unreal.

Mapping the Differences:

Recognize that many Unity-specific components, methods, and properties won’t have a direct counterpart in Unreal. Prepare to think laterally, finding Unreal components that serve a similar purpose or functionality.

3. Converting Member Variables and Enums

In Unity, serialized fields ([SerializeField]) allow private members to be edited in the inspector. In Unreal, you’ll use UPROPERTY macros, which serve a similar purpose but with additional capabilities:

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Game Settings")
int32 Rounds = 3;

Similarly, Unity’s simple enum declarations become a bit more verbose in Unreal to accommodate Blueprint compatibility:

UENUM(BlueprintType)
enum class EDifficulty : uint8
{
 Easy UMETA(DisplayName="Easy"),
 // ... other values ...
};

4. Implementing Game Logic

With member variables in place, dive into the actual script logic:

5. UI Interactions in Unreal

UI design and interaction are considerably different between the two platforms:

1. Unity’s UI elements like TMP_Text or TMP_InputField find equivalents in UMG’s UText and UEditableTextBox.

2. Unity’s event-driven UI interaction system needs a replacement. In Unreal, you can combine C++ methods with Blueprint nodes to create responsive UI.

3. To visually design the UI, Unreal’s UMG editor will be your tool of choice. You can bind properties and functions to UI elements directly within this editor.

6. Testing Your Conversion

Once you’ve transcribed your logic, compiled your C++, and potentially set up related Blueprints:

7. Final Thoughts

Transitioning from Unity to Unreal, especially from C# to C++, can be challenging. However, with a systematic approach, understanding of both engines, and some patience, the process becomes manageable and rewarding. Remember, the aim isn’t always a direct 1:1 translation but achieving similar functionality that feels right within the Unreal ecosystem.

As with all complex tasks, practice, and experience will make future conversions smoother. So, whether you’re bridging skills from Unity to Unreal or vice versa, embrace the learning curve, and relish the growth it promises.

When looking into converting my Word Scramble Challenge I seemed to have opened a can of worms. I thought it would be quick. I am wrong and so it's time to get to work. I have not even opened Unreal yet to try this out, but here is what I have come up with thus far.

The original script for the Unity game

using System.Collections.Generic;
using UnityEngine.UI;
using UnityEngine;
using TMPro;
using UnityEngine.SceneManagement;
public class WordScrambleChallenge : MonoBehaviour
{
 [Header("UI Elements")]
 [SerializeField] private TMP_Text _questionText;
 [SerializeField] private TMP_InputField _answerInputField;
 [SerializeField] private TMP_Text _timerText;
 [SerializeField] private TMP_Text _roundText;
 [SerializeField] private TMP_Text _scoreText;
 [SerializeField] private TMP_Text _feedbackText;
 [SerializeField] private Button _submitAnswerButton;
 [Header("Game Settings")]
 [SerializeField] private int _rounds = 3;
 [SerializeField] private int _timerPerRound = 30;
 [Header("Words By Difficulty")]
 [SerializeField] private string[] _easyWords;
 [SerializeField] private string[] _mediumWords;
 [SerializeField] private string[] _hardWords;
 private int _currentRound = 0;
 private int _score = 0;
 private bool _isPlaying = false;
 private string _currentWord;
 [Header("Difficulty Selection")]
 [SerializeField] private TMP_Dropdown _difficultyDropdown;
 [SerializeField] private Button _playButton;
 [SerializeField] private Button _restartButton;
 private bool _gameStarted = false;
 public enum Difficulty
 {
 Easy,
 Medium,
 Hard
 }
 private Difficulty _currentDifficulty = Difficulty.Easy;
 private void Start()
 {
 _submitAnswerButton.interactable = false;
 // Setup event listeners
 _difficultyDropdown.onValueChanged.AddListener(OnDifficultyChanged);
 _playButton.onClick.AddListener(StartGame);
 _restartButton.onClick.AddListener(RestartScene);
 // Initial UI state
 _playButton.interactable = true;
 _difficultyDropdown.interactable = true;
 }
 private void OnDifficultyChanged(int index)
 {
 switch (index)
 {
 case 0:
 SetDifficulty(Difficulty.Easy);
 break;
 case 1:
 SetDifficulty(Difficulty.Medium);
 break;
 case 2:
 SetDifficulty(Difficulty.Hard);
 break;
 }
 }
 public void SetDifficulty(Difficulty difficulty)
 {
 _currentDifficulty = difficulty;
 }
 public void StartGame()
 {
 if (!_gameStarted)
 {
 _gameStarted = true;
 // Make the Submit button interactable since the game is starting
 _submitAnswerButton.interactable = true;
 StartNewRound();
 // Make Play button and Dropdown inaccessible after the game starts
 _playButton.interactable = false;
 _difficultyDropdown.interactable = false;
 }
 }
 private void StartNewRound()
 {
 if (_currentRound < _rounds)
 {
 _isPlaying = true;
 _currentRound++;
 _roundText.text = $"Round: {_currentRound}/{_rounds}";
 _scoreText.text = $"Score: {_score}";
 StartCoroutine(RoundTimer());
 GenerateScrambledWord();
 }
 else
 {
 EndGame();
 }
 }
 private void EndGame()
 {
 _isPlaying = false;
 _scoreText.text = $"Total Score: {_score}";
 // Reset the game's state for next play
 _currentRound = 0;
 _score = 0;
 _questionText.text = ""; // Clear the last word
 // Prevent submitting answers
 _submitAnswerButton.interactable = false;
 // Reactivate Play button and Dropdown for next round
 _playButton.interactable = true;
 _difficultyDropdown.interactable = true;
 _gameStarted = false;
 }
 private IEnumerator RoundTimer()
 {
 int timeLeft = _timerPerRound;
 while (timeLeft > 0 && _isPlaying)
 {
 _timerText.text = $"Time: {timeLeft}s";
 yield return new WaitForSeconds(1);
 timeLeft--;
 }
 _isPlaying = false;
 StartNewRound();
 }
 public void RestartScene()
 {
 // Restart the current scene
 SceneManager.LoadScene(SceneManager.GetActiveScene().name);
 }
 private void GenerateScrambledWord()
 {
 switch (_currentDifficulty)
 {
 case Difficulty.Easy:
 _currentWord = _easyWords[Random.Range(0, _easyWords.Length)];
 break;
 case Difficulty.Medium:
 _currentWord = _mediumWords[Random.Range(0, _mediumWords.Length)];
 break;
 case Difficulty.Hard:
 _currentWord = _hardWords[Random.Range(0, _hardWords.Length)];
 break;
 }
 _questionText.text = ScrambleWord(_currentWord);
 }
 private string ScrambleWord(string word)
 {
 char[] chars = word.ToCharArray();
 System.Random rand = new System.Random();
 for (int i = 0; i < chars.Length; i++)
 {
 int randomIndex = rand.Next(chars.Length);
 char temp = chars[randomIndex];
 chars[randomIndex] = chars[i];
 chars[i] = temp;
 }
 return new string(chars);
 }
 public void SubmitAnswer()
 {
 if (_answerInputField.text.Equals(_currentWord, System.StringComparison.OrdinalIgnoreCase))
 {
 _score += 5;
 _feedbackText.text = "Correct! + 5 Points";
 }
 else
 {
 _score -= 3;
 _feedbackText.text = "Incorrect! - 3 Points";
 }
 StartCoroutine(HideFeedbackAfterSeconds(2));
 GenerateScrambledWord();
 }
 private IEnumerator HideFeedbackAfterSeconds(float seconds)
 {
 yield return new WaitForSeconds(seconds);
 _feedbackText.text = "";
 }
 public int GetScore()
 {
 Debug.Log($"WordScrambleChallenge Score: {_score}");
 return _score;
 }
}

Converting this Unity C# code to Unreal Engine C++ will involve significant rewriting, given the differences in the frameworks and languages. Below is my attempted start of a step-by-step guide on how to convert this script and integrate it into Unreal Engine:

Step 1: Create an Unreal Engine C++ class

1. Open your Unreal Engine project.
2. Right-click in the Content Browser, navigate to C++ classes, and choose a relevant parent class. In this case, it would be best to start with `UObject` or AActor as a base class.

Name the new class WordScrambleChallenge.

Step 2: Define your headers

The Unreal Engine uses a different set of libraries. Instead of Unity’s UnityEngine, you’ll mostly deal with Unreal’s core classes and utilities.

In WordScrambleChallenge.h:

#pragma once
#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "WordScrambleChallenge.generated.h"
UCLASS()
class YOURPROJECTNAME_API AWordScrambleChallenge : public AActor
{
 GENERATED_BODY()
public:
 // Sets default values for this actor's properties
 AWordScrambleChallenge();
protected:
 // Called when the game starts or when spawned
 virtual void BeginPlay() override;
public: 
 // Called every frame
 virtual void Tick(float DeltaTime) override;
 // ... your class members and functions go here ...
};

Step 3: Declare member variables and enums

Similar to C#, but in Unreal’s style:

UENUM(BlueprintType)
enum class EDifficulty : uint8
{
 Easy UMETA(DisplayName="Easy"),
 Medium UMETA(DisplayName="Medium"),
 Hard UMETA(DisplayName="Hard")
};
UCLASS()
class YOURPROJECTNAME_API AWordScrambleChallenge : public AActor
{
 GENERATED_BODY()
 // ... previous code ...
public:
 UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UI Elements")
 class UText* QuestionText;
 // ... and so on for the other UI elements ...
 UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Game Settings")
 int32 Rounds = 3;
 // ... and so on for the other game settings ...
 EDifficulty CurrentDifficulty;
 // ... the rest of your functions and members ...
};

Note that the UI system in Unreal Engine is called UMG (Unreal Motion Graphics). Instead of Unity’s TMP_Text, you might use UText. Instead of TMP_InputField, Unreal has UEditableTextBox. Adjust accordingly.

Step 4: Implement the logic

This is where most of the heavy lifting happens. You will convert Unity-specific logic into Unreal’s equivalents. For instance:

- Start() in Unity becomes BeginPlay() in Unreal.
- For coroutines in Unity, you would use Timers in Unreal.
- Unity’s SceneManager.LoadScene is equivalent to Unreal’s UGameplayStatics::OpenLevel.

Remember, the process is not a direct 1:1 conversion. It will require understanding both engines and C++ syntax.

Step 5: Blueprints and UMG

For UI interactions and even some logic, Unreal Engine uses Blueprints. After setting up your C++ class, you might want to:

1. Create a Blueprint based on your C++ class.
2. Design the UI using UMG.
3. Hook up the UI and logic in the Blueprint editor.

Step 6: Compile and Test

Finally, compile your project and test your logic and interactions.

Conclusion:

This is a high-level guide to porting the given Unity code to Unreal Engine in C++. It’s a complex process, especially if you’re new to either engine or C++. While the above guide provides a foundation, it will require a deeper dive into Unreal’s documentation, C++ language features, and potentially some troubleshooting to get everything working correctly.