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Unity Engine

User Manual

Script Reference

Unity Engine

Key concepts

Use this reference to key Unity Editor concepts as you work on your first few projects.
Read time 7 minutesLast updated 17 days ago
There are some concepts you rely on from the moment you open the Unity Editor. Use this page to refresh your memory as you work through tutorials and your first projects.

GameObjects, components, and scenes

GameObjects represent everything in your game, including characters, props, and scenery. In the Unity Editor, all objects in a scene are GameObjects. In contrast, project assets are source files that you add to scenes. For example, C# scripts, textures, materials, 3D model files, and prefabs.
GameObjects exist in 2D or 3D environments called scenes. You can think of a scene as a game level, but it might also represent a menu, the credits at the end of the game, or a cutscene.
The behavior of GameObjects is defined by blocks of functionality called components. You can attach multiple components to GameObjects. The following components are fundamental for 3D games:

Component

Impact on a GameObject

TransformDetermines the Position, Rotation, and Scale of each GameObject in the scene. Every GameObject has a Transform component.
Mesh FilterDefines the shape of a 3D GameObject.
Mesh RendererApplies textures and handles how the 3D GameObject looks under lighting examples.
CamerasDefine GameObjects that capture and display the world to the player.
RigidbodyAllow GameObjects to interact with the Physics system, including gravity and collisions. Refer to the Physics section of this guide.
CollidersDefines the shape of a 3D GameObject for the purpose of physical collisions, which can be different from the 3D mesh's visible shape.
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Scripting

Use scripts to create complex game behavior, such as:
  • Trigger game events, such as move the user to a win or lose scene in response to changes in the user's game stats.
  • Change component properties over time. For example, change the visibility of a hidden door, shrink and enlarge an object, or collapse a wall.
  • Respond to user input to move their character, interact with objects, and select menu options.
To add a script to a GameObject, add the Script component, and reference your own script in it.
Unity supports the C# programming language natively.
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3D models

Models are 3D representations of objects. The majority of the visuals for 3D games consist of models, such as characters, interactive objects, and the world around the player.
You can use tools like ProBuilder to create models in the Unity Editor. However, these work best for prototyping, rather than for your final product.
To add more polished 3D assets to your final product, create 3D models, along with their materials and textures, in 3D modeling software, then import them into the Editor.

Left: A 3D polygon mesh for a player character. Right: The player mesh rendered in Unity with materials

Import models into the Editor to use them in your project. The Editor uses the 
.fbx
format. You can also use other common native model formats (for example, 
.max
, 
.blend
, 
.mb
, 
.ma
); the Editor converts them into 
.fbx
when you import them.

Rendering meshes

A 3D mesh is the structural build of a 3D model. It's made up of multiple polygon shapes. To add a 3D model to a GameObject, your GameObject needs two components:
  1. The Mesh Filter component, which includes the actual mesh.
  2. The Mesh Renderer component, which adds a material to the mesh to make the mesh visible in your scene.

Materials

Materials combine information about the visual appearance of a surface, such as textures, color tints, and shaders. Use materials to define how to render surfaces.
  • Textures are any 2D image files that you import into Unity. Use textures to wrap a mesh and add fine detail to a model. Use color tints to alter the color of the texture.
  • Shaders set lighting input and material configuration to control how each pixel renders, which determines how a GameObject looks on a screen.
For material design, refer to the Unity Learn Tutorial.
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Building in-game environments

An environment has been created by adding models and other assets to the scene.

Environment design is the process of creating the world the gameplay takes place in. You can design and build your environment in the Unity Editor, or you can design an environment outside of the Editor and import it.
To build an in-game environment, add GameObjects to the scene and position them to suit your preference and design. You can use ProBuilder to prototype the design and gameplay.
In addition to hand-placing your models in the scene, the Unity Editor includes a built-in set of Terrain features that allow you to add landscapes to your game. In the Editor, you can create multiple Terrain tiles, adjust the height or appearance of your landscape, and add trees or grass to it. Read more about Creating and Using Terrains.
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Animation

Animations describe how objects change based on game states, player interaction, time, and so on. They also give characters their movement, create cutscenes, and change the environment.
There are two ways to add animations to your game:
  • Import animations made in other programs.
  • Animate your assets directly in the Editor.
For more information, refer to the Unity Learn animation topic.

Importing Animations

When you import a model with animation clips, you can choose which of its clips to import. This means you can animate models in a third-party application, then access and edit the clips in the Editor.
For more information, refer to the Animation tab of the Model Import Settings window.

Animating Models in Unity

Use the Animation window to create and modify animation clips in the Editor.
To learn how animation works in the Editor, refer to Mecanim Animation system.

The Animator window

You can use the Animator window to:

Controlling animations

To control which animation clips play, you can:
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Lighting

Light your scenes to add depth and mood to your environments.
All built-in scene templates, except the Empty template, include a single Light GameObject. For most scenes, you'll want to create additional Light GameObjects to create the desired lighting.
For more information, refer to:

A spot light creates atmospheric lighting in this scene

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Audio

To add background music and sound effects to your game, refer to Audio Overview. You'll need to use third-party software to create your audio and import it into the Editor. Then, you can mix your sounds, place them in scenes, and create ambient sound.
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Physics

The Player character has a capsule collider component that uses the Physics system to allow the character to collide with the walls.

Use Unity’s physics system to control how objects interact with each other and with their environment. For example, you can:
  • Use forces, such as gravity and mechanics, which define how GameObjects behave on collision.
  • Create custom physics to fit the design of your game, which might not require an accurate simulation of Earth.
To learn how to use Unity’s physics system, you can refer to:
To apply the physics system to a GameObject, use the
Rigidbody

?

and
Collider

?

components:

Component

Impact on a GameObject

RigidbodyAllows your GameObject to be affected by the physics system, and react to things like gravity and collisions.
ColliderEnable GameObjects to interact with other GameObjects in the scene. For example, GameObjects with a collider can move or be moved by another GameObject with a collider.
Collider with a triggerCall a function in code when two GameObjects intersect.
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User Interface

To create interface elements, such as menus, gear lists, and information pop-ups, use UI Toolkit.
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Additional resources