Best Practices For Referencing Gameobjects And Components
Why References Matter
Using efficient references to GameObjects and Components is crucial for optimized Unity performance. Failing to properly cache references can lead to expensive Find calls, resulting in frame rate drops. Thoughtfully organizing references also keeps code clean and maintainable.
Avoiding Expensive Finds
Finding GameObjects or Components at run time using Unity’s built-in methods like FindObjectOfType is convenient, but extremely inefficient. These lookups traverse the entire scene hierarchy, compare names or tags, and cast to the desired Component type – an expensive set of operations that is fine for Setup, but disastrous if done every frame.
Optimizing Performance
Caching references during Start or Awake allows interacting with GameObjects and Components directly, bypassing expensive lookups. This keeps performance smooth, preventing frame rate spikes and instability. Building games that run fast and smooth is only possible with optimized reference handling.
Maintaining Organized Code
Thoughtfully organizing references also keeps code sane as projects grow in complexity. Define clear access patterns based on access needs, group together related references, use descriptive names – treat references as first-class citizens vital to clean code.
Referencing GameObjects
Finding by Name
Finding a GameObject by name using GameObject.Find can be convenient, but iterates through every object in the scene. Use this only for single-time setup logic, not per-frame update loops:
public GameObject player;
void Start() {
player = GameObject.Find("Player");
}
Finding by Tag
Finding by tag avoids string comparisons but still traverses the entire scene. This is faster than name lookups but should not be used frequently at runtime either:
public GameObject player;
void Start() {
player = GameObject.FindWithTag("Player");
}
Finding by Layer
Pre-layering GameObjects and finding by Layer uses GameObject.LayerMask for targeted traversals. This leverages Unity’s optimized layer handling and avoids all name comparisons:
public GameObject player;
void Start () {
player = GameObject.FindGameObjectsWithTag(LayerMask.NameToLayer("Player"));
}
Caching References
For frequent access, search once and cache the reference for reuse. Here, the player GameObject reference is cached on Start for use in Update each frame:
public GameObject player;
void Start() {
player = GameObject.Find("Player");
}
void Update() {
// Access cached player reference
player.GetComponent<PlayerController>().Move();
}
Referencing Components
Getting the Component
Accessing Components should leverage the GameObject GetComponent method, avoiding expensive lookups. GetComponent also caches the result internally, for even better performance:
void Start() {
PlayerController controller = player.GetComponent<PlayerController>();
}
Caching the Component Reference
Frequently accessed Components should be cached for maximum efficiency:
public PlayerController controller;
void Start() {
controller = player.GetComponent<PlayerController>();
}
void Update() {
// Access cached reference
controller.Move();
}
Null Checking
GetComponent can return null if the GameObject lacks the specified Component. Always check for null to avoid errors:
PlayerController controller = player.GetComponent<PlayerController>();
if(controller != null) {
// Use the controller reference
}
Organizing References
Private Fields
References only needed internally should be declared as private fields, encapsulating usage:
private PlayerController controller;
Public Properties
References needing external access can expose properties for get/set access:
public PlayerController Controller { get; private set; }
Folders by Type
Group references together in folders by type for easy understanding and modification:
MyGameObject
- Components
- PlayerController
- Helpers
- InputHelper
- Managers
- AudioManager
Naming Conventions
Use descriptive names clearly conveying context and purpose: playerController vs playerCntrlr. Avoid redundant prefixes: controllerController is confusing.
Common Reference Issues
Memory Leaks
Neglecting to clear references for destroyed GameObjects causes them to remain in memory indefinitely. Always reset references on destruction.
Null Reference Exceptions
Assuming a reference is assigned without null checking causes exceptions at runtime. Check for null before usage.
Broken References
Refactoring code can lead to missed reference updates, breaking functionality. Review all references carefully when refactoring.
Strategies for Avoiding Issues
Adopt consistent reference patterns, favor caching over frequent finds, encapsulate references as private fields with public properties, and add existence checks before using references.
Referencing Hierarchically
Parents and Children
GameObjects often have hierarchical relationships for aggregated control. Children can find parents and vice versa:
public GameObject parent;
parent = this.gameObject.transform.parent.gameObject;
Tree Traversal Strategies
Traverse object trees breadth-first for shallow hierarchies or depth-first for deep nested structures. Cache visited references to avoid redundant traversals.
Example Traversal Code
void TraverseChildren() {
Queue children = new Queue();
foreach (Transform child in transform) {
children.Enqueue(child);
}
while (children.Count > 0) {
Transform child = children.Dequeue();
// Process child
foreach (Transform grandChild in child) {
children.Enqueue(grandChild);
}
}
}
Advanced Referencing Patterns
Dependency Injection
Externalizing reference handling into a dedicated class allows swapping implementations. Useful for testing and mocking.
Singletons
Centralizing global references in a singleton class provides unified access. But avoid overusing singletons, as they introduce hidden dependencies.
Object Pools
Pooling reusable object references avoids repetitively instantiating/destroying. Great for effects like particles or bullets.
