How do I change vertices of a tree from Terrain in Unity3d with script?

Question

I have placed some trees onto the terrain via editor. I have an object which is passing throuh trees and when this object collides with certain tree I want to change its vertices.

void OnTriggerEnter (Collider col) {
    DestroyableTree tree = col.gameObject.GetComponent<DestroyableTree>();

    if (tree == null)
        return;

    Mesh mesh = tree.GetComponent<MeshFilter>().mesh;
    Vector3[] vertices = mesh.vertices;

    for (var i = 0; i < 100; i++){  // 100 just random number, as well as 50 bellow
        vertices[i].x = 50;
        vertices[i].z = 50;
    }
    mesh.vertices = vertices;
    mesh.RecalculateBounds ();
    mesh.RecalculateNormals ();
    tree.GetComponent<MeshFilter> ().mesh = mesh;

    //tree.UpdadeMesh(tree, mesh);
    //tree.Delete();
}

DestroyableTree is from http://rene.klacan.sk/unity3d/games/2014/10/28/destroyable-terrain-trees-in-unity/

When uncommented tree.Delete() lets me be sure that I was trying to edit correct tree. When I debug I can see that vertices of mesh have changed but why they won't update during runtime of game scene?

EDIT: it is probably because I am accesing capsule component's mesh but not of the tree itself. Still how do I access mesh of trees on the terrain (not necessarily with the code displayed above)?

Answer 1

Using code provided in the link above and having it modified a bit worked. Although it didn't solve the very root issue why I had to ask this question in the first place :(

So here it is how I did it, simple: in the class DestroyableTree that René Klačan wrote I added additional field public TreeInstance treeInstance; which gets initialized after marked statement (in the picture bellow) by adding tree.treeInstance = treeInstance; : After that I had to reach mesh of the tree using tree.treeInstance.GetComponent<MeshFilter>().mesh; in my code at the beggining of the question. I hope someone will find this useful.