unity.md

title	description	comments
Roblox for Unity Developers	If you're an experienced Unity developer, use this page to get oriented with Roblox.	This document could use more information (and some links) around replication, remote events, and cloud services.

import ScriptTypes from './includes/engine-comparisons/script-types.md' import CodeSample from './includes/engine-comparisons/fishing-pole-code-sample.md' import ScriptLocations from './includes/engine-comparisons/script-locations.md' import Transforms from './includes/engine-comparisons/transforms.md'

This page includes information to help experienced Unity developers get started with Roblox: basic orientation, a conceptual comparison, and key differences between the two platforms.

Getting Oriented

Unity's Hierarchy window and Roblox Studio's Explorer are the primary windows for organizing elements in 3D scenes:

• Both allow you to manage and organize objects (for example, characters and environmental assets).
• Both use a tree structure for the parent-child relationships between objects.

However, the Hierarchy window has no predefined structure, whereas the Explorer window has a strict structure. It might help to think of the Explorer window as a combination of Unity's Hierarchy and Project windows, with the Workspace folder as the most recognizable element.

Similarly, the Roblox Studio Asset Manager and Toolbox overlap with the Unity Project window. The Asset Manager lets you manage all assets within your experience, whereas the Toolbox lets you access any assets you've published. The Toolbox also lets you search the Creator Store for assets from Roblox or the community, similar to the Unity Asset Store.

Philosophical Differences

Roblox is a "simulation engine" rather than a traditional game engine. Unity GameObjects and Roblox Class.Part|Parts both serve as the fundamental building blocks for creating objects in a 3D environment, but in practice, the two are quite different:

• Representation: GameObjects in Unity are a higher-level concept for any object in a scene, whereas Parts in Roblox are designed to represent physical objects like wooden blocks and plastic spheres, rather than abstract geometry like primitive objects in Unity.
• Physics: To perform physics simulations in Unity, you attach components like Rigidbody and Collider to a GameObject. In Roblox, physics are built into the Parts data type; the engine handles interactions automatically.

You can see the difference immediately if you create a GameObject and a Part. The GameObject has nothing more than a position, rotation, and scale. The Part has that same information—plus a material and color, values for reflectance and transparency, mass and shape, and much more. Turning a Part into something more akin to an empty GameObject means removing a lot of built-in properties. Conversely, you can make a GameObject that looks a lot like a Part by adding MeshFilter, MeshRenderer, Collider, and Rigidbody components to it.

From a scripting perspective, GameObject is most similar to the Roblox Class.Instance, the base class for all other Roblox classes, but because you don't (and can't) create objects of type Instance, the comparison isn't especially practical.

Another comparison is the Unity GameObject to the Roblox Class.Model. Models act as a container for a collection of interconnected parts in the same way that you might establish a parent-child relationship between many GameObjects in Unity. You specify one of the model's parts as its primary part to define the pivot point. Models also hold scripts, animations, sound effects, prompts, constraints, particle emitters, and more.

For example, a Unity GameObject might have components for ParticleSystem, Physics3D, SpringConstraint, and a script. In the Hierarchy window, you see a single GameObject named SpringyFireball. The Inspector window shows the collection of components and properties.

In Roblox, a comparable SpringyFireball model in the Explorer window might look something like this:

Model
|- ParticleEmitter
|- MeshPart
|- SpringConstraint
|- ClickDetector
|  |- Script

Roblox's physics-by-default philosophy extends to the process of building 3D models. In Roblox, welding multiple parts together into an assembly is an excellent way to quickly build things, because Roblox treats the welded parts as a single rigid body. This approach isn't available in Unity.

Rather than using standard metric units for length and mass, Roblox uses notional units called studs and Roblox Mass Units (RMUs). For approximate metric conversions and recommendations around use, see Units.

Location Matters

Roblox experiences are multiplayer by default, so Roblox Studio includes many different storage locations with specific behaviors. For example, a script might run when you put it in Class.ReplicatedStorage, but not when you put it into Class.StarterPlayerScripts. For more information, see Client-Server Runtime and Object Organization.

Scripting

Unity doesn't have the concept of different script types. If you choose to make a multiplayer game, Unity uses its networking libraries to indicate when a GameObject (and its scripts) should be exclusive to the server.

In Unity, much of the engine's functionality is available through the methods of MonoBehaviour. For example, to run code before the render loop, you add code to the Update() method. To handle physics collision events, you add code to the OnCollideEnter() method.

Roblox scripts are more event-driven. You access similar functionality by subscribing to services and listening for updates.

C# and Luau

For scripting, Unity uses C#. Roblox uses Luau, a scripting language derived from Lua 5.1.

Compared to C#, Luau is gradually typed and generally has a less verbose syntax. In larger projects, however, gradual typing can introduce categories of bugs that strongly typed languages like C# avoid, so consider enabling strict type checking in Roblox scripts.

For basic syntax differences between the scripting languages, see Luau and C# Comparison.

Luau Code Sample

The Roblox script can be relatively concise because Roblox has many built-in assumptions: a Class.Player with a Class.Humanoid character connected to the server and can equip Class.Tool|Tools. These assumptions don't exist in Unity, so the implementation would be very different.

Assets

Unity and Roblox both support importing custom meshes and models in .fbx format. Certain types of assets may require specific configurations and export settings from your third-party modeling software. For more information, see the following pages:

• 3D Importer
• General Specifications
• Blender and Maya Export Requirements

In Unity, objects import into your Assets directory, visible in the Project window. In Roblox, assets import into your Workspace and into the Toolbox or Inventory section of the Asset Manager.

Roblox also offers an open-source Blender plugin to streamline the import process.

Transforms

Collaboration

In Unity, you collaborate with standard version control systems or paid services like Unity Version Control.

Roblox files live in the cloud (although you can export copies), so Roblox Studio provides built-in collaboration workflows for simultaneous editing, group management, permissions, script drafting, and more. See Collaboration.

Cloud syncing provides further benefits with [packages](projects/assets/packages.md), the Roblox equivalent of Unity prefabs. Converting an asset or asset hierarchy to a package helps with local reusability, but also with collaboration. When you or your collaborators publish a new version of a package, you can quickly update existing instances of that package within an experience or set them to auto-update.

Plugins

Similar to Unity tools, Roblox Studio supports plugins, which can simplify or give you additional control over various aspects of the development process. Plugins are available in the Creator Store, just like assets, many for free.

Glossary

Unity	Roblox	Notes
Scene	Place
GameObject	Class.Part or Class.Model	See Philosophical Differences.
Prefab	Package
Transform	Datatype.CFrame	CFrame doesn't include scale information. See Transforms.
Hierarchy window	Explorer window
Inspector	Properties window
Scene view	Viewport
Game view	Viewport	The Viewport transitions into a gameplay view when you test your experience.
Project window	Asset Manager or Toolbox
Terrain Inspector	Terrain Editor
Spawn point	Class.SpawnLocation
Console	Output
Asset Store	Creator Store
Overlays	Menu bar
Tool	Plugin