Editing custom class' variable in IENumerable

Questions & Answers
1

I am current writing a terrain generator that creates terrain using unity’s inbuild terrain manager. I have, however run into problems with creating the individual chunks. All of the chunks work and generate, but there is a small line between them. I know this to be my problem, and i started to organise a system for saving each individual chunk that has been generated in an array, so that I can connect them together using Terrain.SetNeighbors. So I created a custom class to organise this, the class Chunk.

You can see this code I have here this is the code with the creation of the chunks, and the pass through to the individual chunk generators. This code doesn’t work.

function ChunkAtPos(Position : Vector2)
	{
	var ChunkObject = Instantiate(ChunkPrefab, Vector3(Position.x*256, 0, Position.y*256), Quaternion.identity);
	
	ChunkObject.transform.parent = transform;
	var CurrentChunk : Chunk;

    CurrentChunk.Position = Position;
	
	yield ChunkObject.GetComponentInChildren(TerrainGen).GenerateTerrain(Position);
	}

class Chunk
	{
	var Position : Vector2;
	var ChunkObject : GameObject;
	}

I get an error:

NullReferenceException: Object reference not set to an instance of an object
ChunkGen+$ChunkAtPos$113+$.MoveNext () (at Assets/Scripts/ChunkGen.js:59)
UnityEngine.MonoBehaviour:StartCoroutine_Auto(IEnumerator)
$:MoveNext() (at Assets/Scripts/ChunkGen.js:24)

So, if I remove line 59,

CurrentChunk.Position = Position;

The code runs fine and my terrain generates.
This also happens if i try edit any other part of my CurrentChunk variable. I have also tried having a constructor inside my class, among other things.

tl;dr:
Editing the class of a custom variable in my terrain generation script, which uses yields and IENumerables gives an error

Thanks for your help!

2

You don’t initialize your currentChunk, so it gets its default value. The default value for reference types is null.

Because Chunk is not a MonoBehaviour class, you have a constructor in it (default is empty constructor) and can create a new instance of Chunk by

var CurrentChunk : Chunk = new Chunk();

I think in UnityScript the new keyword is optional.

Another thing I noticed worth mentioning is that you don’t (seem to) store your CurrentChunk anywhere, as CurrentChunk is created as a local variale. Essentially you’re just creating needless garbage on the heap every time you call this function, which will cause Garbage Collection to run more frequently, decreasing performance.