2. Unity's building blocks

Building Blocks

• Unity games consist of Scenes
• Scenes consist of GameObjects
• GameObjects consist of Components

Scenes

• Manual: Scenes
• Scene is a container for content
  • A game can be just one scene, or a combination of multiple ones
• Example scenes:
  • Main Menu
  • Level
  • Game Over
• Create New Scene: Assets > Create > Scene
• New scenes use Unity's default Scene template, but you can create your own
  • Manual: Scene templates

GameObjects

• Manual: GameObjects
• Pretty much everything in Unity is a GameObject
• Fundamental objects in Unity that represent characters, props and scenery
• Some examples...
  • Manual: 3d primitives: Cube, Cylinder, Sphere
  • Camera
  • Light
  • Empty

GameObject Hierarchy

• GameObjects can have multiple child GameObjects they become parents
• Children inherit their parent's...
  • position
  • rotation
  • scale
  • activeness
• Manual: Hierarchy: Parenting
• Manual: Transform: Parenting
• Note: Rotating child GameObjects can have wonky results if parent has any other scale than .

Components

• Manual: Components
• GameObjects act as containers for Components that implement various functionalities
• GameObject's components and their settings are listed in the Inspector window

Some important components

Spatial information

• Transform
  • Manual: Transform
  • position, rotation, scale
  • parenting information
  • included in every GameObject

Interacting with other GameObjects

• RigidBody
  • Manual: RigidBody
  • for interacting with the physics engine
  • can receive forces and torque
• Collider
  • Manual: BoxCollider
  • enables collision with other GameObjects
  • there are different shapes and sizes
    • CapsuleCollider(2D), BoxCollider(2D), PolygonCollider2D...
  • isTrigger
    • -> Collider is ignored by the physics engine, but can trigger events

Drawing the GameObject

• MeshFilter
  • The mesh, or the 3d geometry of a GameObject
• Renderer
  • Manual: MeshRenderer
  • The component for drawing the GameObject on screen
  • MeshRenderer, SpriteRenderer, LineRenderer, TrailRenderer...
• Material
  • Manual: Material Inspector Reference
  • MeshFilter only defines the geometry, but the Material component defines color and other properties

Custom Functionality

• Script
  • Manual: Scripting
  • The most versatile component
  • For inserting custom C# code into the GameObject
  • We'll dive deeper into this in 4. Scripting GameObjects