Remove trees from the terrain during runtime?

Unity Engine
1

Hello,

I have looked at several threads on how to remove a tree from a terrain (during the game), and I’ve written my own script. But I can’t figure out why my script won’t work. I should say that most of the examples are in C# (of course :roll_eyes:), and I mainly use Javascript/Unityscript. But that aside, I still am at a loss as to why it’s not working.

Here is my script:

//#pragma strict

public var amountOfWood : int = 100;

//Tree array for the terrain data
private var treeArray : TreeInstance[];
private var treeArrayJS = new Array();

private var distance : float;

private var terrain : TerrainData;
private var i : int;
private var thisTransform : Transform;

//The closest tree's position
private var closestTreePosition : float;
//Nearest tree to the collider
private var nearestTree : TreeInstance;


function Start () {

thisTransform = transform;
treeArray = Terrain.activeTerrain.terrainData.treeInstances;

treeArrayJS = new Array(treeArray);
//Debug.Log(treeArrayJS.length);

terrain = Terrain.activeTerrain.terrainData;

}

function Update () {


	if(amountOfWood <= 0) {
	
	
				// Our current closest tree initializes to far away
                var maxDistance : float = Mathf.Infinity;
                
                for (i = 0; i < treeArrayJS.length; i++)
                {
                	//Get the trees world position on the terrain
					var treePosition : Vector3 = Vector3.Scale(treeArrayJS[i].position, terrain.size);
		
                	//Check the distance between the tree collider and the tree's position
					closestTreePosition = (treePosition - thisTransform.position).sqrMagnitude;
            	
            		if(closestTreePosition < maxDistance) {
            			maxDistance = closestTreePosition;
      
                		nearestTree = treeArrayJS[i];
                		//Debug.Log(nearestTree);
                		
                					
                					
            		}
                
                }
 
                // Remove the tree from the terrain tree list
                treeArrayJS.Remove(nearestTree);
                treeArray = treeArrayJS.ToBuiltin(TreeInstance) as TreeInstance[];
	
	
	}



}

When this script executes, nothing happens. I don’t get any errors, but nothing at all happens.

Thanks for any help.

2

Throw in some Debug.Log statements at key points to make sure you’re even getting to them. If not, then figure out why.

3

When I debug.Log the Javascript array (after building it from the default treeInstances array), I get that there are 78 objects in the array. Which sounds right. 78 trees looks right to me as I look at my terrain.

Then when I Debug.Log the nearestTree variable in the “for” loop, I get about 78 logs like this:
UnityEngine.TreeInstance
UnityEngine.Debug:Log(Object)
ResourceHolder:Update() (at Assets/Scripts/ResourceHolder.js:54)

I can’t figure out why it won’t remove the closest tree to “x”.

4

Well I got it working thankfully. Took me about a day and a half to finally figure out why Unity no comprende, but thats why I hate and love programming lol.

My main stumbling block was this line at the bottom of the script:

treeArray = treeArrayJS.ToBuiltin(TreeInstance) as TreeInstance[];

For some reason, even though I referenced the actual treeInstance array at start, I actually had to “manually” reference it like this:

Terrain.activeTerrain.terrainData.treeInstances = treeArrayJS.ToBuiltin(TreeInstance) as TreeInstance[];

And then it worked. Why? I have no idea. Syntax wins again.

45 trial and error runs later…:shock::-x

5

Weird. Glad you got it sorted!

6

It’s because object variables in JS (and mostly in C#) are “references”, basically a thing which points to something else. Your “treeArray” variable is a different reference than Terrain.activeTerrain.terrainData.treeInstances. They are two different references both pointing to the same thing. When you reassign treeArray you make it point to a different array, but it doesn’t make Terrain.activeTerrain.terrainData.treeInstances point to it.