Hi everyone,
a lot of people have a lot of thoughts and opinions on when to use references to GameObjects, scriptable objects, static classes, Singletons etc. and I, too, have some practices I usually folllow. However, as my perspective on Game development with Unity is that of a C# programmer in non-game development, I sometimes wonder how things actually work.
I quickly understood that GameObjects are actually objects in the sense of C# that inherit from classes in the UnityEngine namespaces, as are components, the latter most importantly inheriting from the ubiquitous MonoBehaviour class. That means every component I attach to a game object will become an instance of the corresponding class at runtime and every game object will be an instance, too.
Now what I would like to understand is: When and how are these instances created? Note I mean instance in the OOP sense, not like instantiating a prefab (even though those are related). I especially wonder how the ubiquitous fields in my classes are set that I use to fill in from the inspector at edit time, typically like this:
public class Something : MonoBehaviour {
public MyClass someStuff;
...
How do my components I dragged across the editor end up in the someStuff field of my Something’s instance? And what is the difference between that and doing a GetComponent() in Start() at runtime?
It is generally advised to not use GetComponent() in Update() which seems obvious to me. It seems, however, to be more controversial, if it is a good idea to avoid the usage of GetComponent() entirely. Often you can avoid it by using a field you can fill from the inspector, but that comes with other problems, so I wonder if it’s worth it - and why.
Please help me understand what happens inside the engine. If possible, I would appreciate links to the corresponding parts of the Unity reference source code. If there’s documentation or articles about it that are official and reliable, I’d appreciate those, too.
Thank you!
Edit: I already came across a link this blog post in another topic where someone asked something similar but it’s down. Apparently a lot of it comes down to serialization.