praca_magisterska/games/unreal/tutorial/appendix-c-unity-conversion.md

Appendix C: Unity to Unreal Conversion Notes

← Appendix B: Troubleshooting | Back to Index

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Scale Conversion

Unity	Unreal	Notes
1 unit = 1 meter	1 unit = 1 centimeter	Multiply Unity values by 100

Example:

• Unity speed: 7.5 → Unreal speed: 750
• Unity position: (5, 10, 0) → Unreal position: (500, 1000, 0)

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Coordinate System

Axis	Unity	Unreal
Up	Y	Z
Forward	Z	X
Right	X	Y

For 2D top-down games:

• Both use X for horizontal
• Y/Z swap for vertical

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Common Operations Comparison

Input

Unity:

float h = Input.GetAxisRaw("Horizontal");
float v = Input.GetAxisRaw("Vertical");

Unreal (Enhanced Input):

1. Create Input Action (IA_Move) with Axis2D type
2. Create Input Mapping Context with key bindings
3. Add Mapping Context in BeginPlay
4. Use "Get Action Value" node to read input

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Instantiate / Spawn

Unity:

Instantiate(prefab, position, rotation);

Unreal:

Spawn Actor from Class
├── Class: YourBlueprintClass
├── Spawn Transform Location: position
└── Spawn Transform Rotation: rotation

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Destroy

Unity:

Destroy(gameObject);

Unreal:

Destroy Actor
└── Target: Self (or reference)

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Delta Time

Unity:

Time.deltaTime

Unreal:

Get World Delta Seconds

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Find Objects

Unity:

FindObjectOfType<PlayerController>();
FindObjectsOfType<Enemy>();

Unreal:

Get All Actors of Class
├── Actor Class: BP_Player
└── Out Actors: (array)

Then: Get (a ref) → index 0

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Singleton Pattern

Unity:

public static GameManager Instance { get; private set; }

void Awake() {
    Instance = this;
}

Unreal Options:

1. Game Instance - Persists across levels
2. Subsystem - Engine-managed singleton
3. Get All Actors of Class - Find at runtime

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Coroutines vs Timers

Unity:

StartCoroutine(DelayedAction());

IEnumerator DelayedAction() {
    yield return new WaitForSeconds(2.0f);
    DoSomething();
}

Unreal:

Set Timer by Function Name
├── Function Name: "DelayedAction"
├── Time: 2.0
└── Looping: false

Or use Delay node in blueprints.

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Physics Layers vs Collision Channels

Unity:

• Layer-based collision matrix
• Physics.IgnoreLayerCollision()

Unreal:

• Collision Channels (Object Types)
• Collision Presets
• Per-component collision settings

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Tags

Unity:

if (other.CompareTag("Enemy")) { }

Unreal:

Actor Has Tag
├── Target: Other Actor
└── Tag: "Enemy"

Or use Cast To for type checking (preferred).

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Vector Math

Operation	Unity	Unreal
Normalize	vector.normalized	Normalize node
Magnitude	vector.magnitude	Vector Length node
Dot Product	Vector3.Dot(a, b)	Dot Product node
Cross Product	Vector3.Cross(a, b)	Cross Product node

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Random

Unity:

Random.Range(0f, 1f);
Random.Range(0, 10); // int, exclusive max

Unreal:

Random Float in Range
├── Min: 0.0
└── Max: 1.0

Random Integer in Range
├── Min: 0
└── Max: 9  // inclusive!

⚠️ Note: Unreal's integer range is INCLUSIVE on both ends!

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Debug

Unity:

Debug.Log("Message");
Debug.DrawLine(start, end, Color.red);

Unreal:

Print String
└── In String: "Message"

Draw Debug Line
├── Line Start: start
├── Line End: end
└── Line Color: Red

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Quick Reference Table

Concept	Unity	Unreal
Script	C# MonoBehaviour	Blueprint / C++ Actor
Prefab	.prefab asset	Blueprint Class
Scene	.unity scene	Level (.umap)
Inspector	Inspector window	Details panel
Hierarchy	Hierarchy window	Outliner
Project	Project window	Content Browser
Console	Console window	Output Log
Play	Play button	Play (Alt+P)

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← Appendix B: Troubleshooting | Back to Index