UnityToGodot

This repository is meant to keep track of what needs to be done to port a Unity codebase to Godot. It is a WORK IN PROGRESS, and will include my findings and any tools/scripts that are useful in the process.

Porting Steps

Unity Concept	Godot Replacement	Notes
.meta files	Remove all .meta files	On MacOS, search for .meta and delete. TODO: create a script for this
[SerializeField]	[Export]
Auto serialized public fields	[Export]	Unity auto-synthesizes public fields. Godot does not. Add [Export] to fields you want to serialize.
[SerializeField] List<Vector3> vectors = new();	[Export] public Vector3[] vectors;	Export list for serialization
void Awake()	public override void _Ready()	Unity calls Awake with random order. Godot calls _Ready in order from child to parent to root.
void Start()	No exact equivalent	Requires custom solution
void Update() using Time.deltaTime for time step	public override void _Process(double delta) using delta parameter for time step
void FixedUpdate() using Time.fixedDeltaTime for time step	public override void _PhysicsProcess(double delta) using delta parameter for time step
.zero	.Zero
implicit conversion between Vector3 and Vector2	Not supported
[Range(0, 20)]	[Export(PropertyHint.Range, "0,20,")]
radians = degrees * Mathf.Deg2Rad	radians = Mathf.DegToRad(degrees)
degrees = radians * Mathf.Rad2Deg	degrees = Mathf.RadToDeg(radians)
Mathf.PI	Mathf.Pi	Pi (π) constant
Random.InitState(seed)	GD.Seed(seed)	Initialize random number generator seed
Random.Range(min, max)	GD.Randi() % valueRangeSize + minValue	Generate random integer
Random.value	GD.Randf()	Generate random float between 0-1.0f (inclusive)
Color.red	Colors.Red	Color constants
gameObject.name	node.Name	In Godot, the names of sibling nodes must be unique from each other. If you change the node name to an existing name it will be automatically renamed (From in-code documentation).
rigidbody.isKinematic	physicsBody2D is CharacterBody2D	Test: Is kinematic
new Vector2(spriteRenderer.size.x, spriteRenderer.size.y)	sprite2D.Texture.GetSize()	Get sprite size in pixels
spriteRenderer.color	sprite2D.Modulate	Get sprite modulate color
spriteRenderer.flipX = true	sprite2D.FlipH = true	Flip sprite horizontally
spriteRenderer.flipY = true	sprite2D.FlipV = true	Flip sprite vertically
[Tooltip("tooltip")]	No equivalent	Not available in C# for Godot. Documentation ("Currently only @GDScript has annotations")
.x	.X	Vector types
.y	.Y	Vector types
.up	.Up	Vector types
.down	.Down	Vector types
.z	.Z	Vector3
.forward	.Forward	Vector3
.normalized	.Normalized()	Vector types
.magnitude	.Length()	Vector types
GameObject	Node	See Porting Problems section for more information
Vector2Int	Vector2I
Vector3Int	Vector3I
DestroyObject(gameObject)	QueueFree()	Destroy node in scene
transform.childCount	GetChildCount()	Get count of children for MonoBehaviour (Unity) vs Node (Godot)
transform.localEulerAngles = new Vector3(0, 0, -newAngle.Degrees)	RotationDegrees = newAngle.Degrees	2D rotation
transform.parent	GetParent()	Get node parent
foreach (Transform childTransform in transform)	foreach (var child in GetChildren())	Iterate through children for MonoBehaviour (Unity) vs Node (Godot)
OnTriggerEnter2D	Code Sample
OnCollisionEnter2D	Code Sample
AudioListener	AudioListener2D, AudioListener3D	Audio
AudioSource	AudioStreamPlayer, AudioStreamPlayer2D, AudioStreamPlayer3D	Audio
GlobalLight2D, Light2D	CanvasModulate, DirectionalLight2D, PointLight2D, LightOccluder2D	2D Lighting
using UnityEditor;	Remove all
using UnityEngine.XXX;	Remove all
using UnityEngine;	using Godot;
Debug.Log	GD.Print
Input Actions	InputEvent/InputMap	Godot Documentation: InputEvent
Rigidbody2D as child component	RigidBody2D as parent node or CharacterBody2D as parent node	In Godot, the roles of ownership between a node and its rigidbody are reversed
Unity packages	Remove all	Remove installed Unity packages from the Assets/plugins folder
n/a	partial class requirement	Because of the way Godot builds C# code, you'll get a build error for classes that subclass a built-in Godot class and don't use partial. Documentation: Godot Interop With Source Generators
n/a	Godot type name conflicts	If you have any types in your code that conflict with built in Godot types, use namespace to wrap them.
Prefab	Scene	Godot Documentation: Where Are My Prefabs

Godot Limitations

Summary	Problem Statement	Solution
No visual scene while running	In Unity, you can view a scene visually in the editor. In Godot, you can see the list of nodes in the Scene tree while running in the Remote tab, but you can't view the objects visually in the scene editor.

Porting Problems

Summary	Problem Statement	Solution
Components vs Nodes	In Unity, each GameObject can have multiple Components (via MonoBehaviour). In Godot, each Node is the component.	Create a separate node for each behavior, instead of a separate component. This requires rethinking logic around finding the target for a particular behavior. Instead of using gameObject directly, in Godot you might operate on the parent node, for example.
No transform in Node	In Unity, every GameObject has a transform. In Godot, Node doesn't have a transform, so you're forced to choose if your code subclasses Node2D or Node3D.	Duplicated code for Node2D vs Node3D or utility structs that can operate on either a Node2D or Node3D. Example: Transform tool that can set the position of either node type.
2D Physics Sprite2D not working	After adding RigidBody2D, sprite doesn't move or interact with physics.	Sprite must be child node of RigidBody2D. This is different than Unity, where the RigidBody component is attached to the GameObject along with the sprite renderer.
Strange scaling for physics sprite	When adding RigidBody2D to a Sprite2D you might see strange scaling when the game is running.	Check all Node2D transforms in parent nodes of the sprite and make sure they are (1, 1). Documentation: https://stackoverflow.com/questions/77590667/godot-physics-resizing-my-sprites-at-runtime
C# 10 support	Godot supports C# 10, Unity does not. This means writing code that works for both engines is more difficult if you want to use the newest language features.	No solution

Code Samples

Godot Code Samples

Detect 2D Collisions

var collision = characterBody2D.MoveAndCollide(velocity);

or

characterBody2D.Velocity = velocity;
characterBody2D.MoveAndSlide();
for (int i = 0; i < characterBody2D.GetSlideCollisionCount(); i++)
{
    var slideCollision = characterBody2D.GetSlideCollision(i);
    GD.Print("Collided with: ", (slideCollision.GetCollider() as Node).Name);
}

Detect Mouse Click on Node

• Set the Pickable property to true on your CharacterBody2D
• Make sure your CharacterBody2D has a child collision node
• In the Signals panel for your character body node, connect the input_event to your script

public void _on_character_body_2d_input_event(Node viewport, InputEvent @event, int shape_idx)
{
    if (@event is Godot.InputEventMouseButton)
    {
        if (@event.IsPressed())
        {
            GD.Print("Mouse Press");
        }
        else
        {
            GD.Print("Mouse Release");
        }
    }
}

Troubleshooting

Problem	Possible Solutions	Notes
Trouble with VSCode and Intellisense	?Reinstall .NET SDK?	Unverified. Still Investigating

TODO: Will add more notes as I port more code