Procedural Terrain for Unity

ProceduralTerrain.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ProceduralTerrain : MonoBehaviour
{
    Vector3[] vertices;
    int[] triangles;
    Mesh mesh;

    public int xSize = 20;
    public int zSize = 20;
    MeshCollider meshCollider;

    float timer = 0f;
    bool done = false;

    // Start is called before the first frame update
    void Start()
    {
        mesh = new Mesh();
        GetComponent<MeshFilter>().mesh = mesh;
        meshCollider = gameObject.AddComponent<MeshCollider>();

        CreateShape(0f);
        UpdateMesh();

    }

    void CreateShape(float h){
        vertices = new Vector3[(xSize+1) * (zSize +1)];
        int i = 0;
        for(int z=0; z <= zSize; z++){
            for(int x=0; x <= xSize; x++){
                float y = Mathf.PerlinNoise(x*.3f, z*.3f) * h;
                vertices[i] = new Vector3(x,y,z);
                i++;
            }   
        }

        triangles = new int[xSize * zSize * 6];

        int vert = 0;
        int tris = 0;

        for(int z=0; z< zSize; z++){
            for(int x=0; x < xSize; x++){
                triangles[tris + 0] = vert + 0;
                triangles[tris + 1] = vert + xSize + 1;
                triangles[tris + 2] = vert + 1;
                triangles[tris + 3] = vert + 1;
                triangles[tris + 4] = vert + xSize + 1;
                triangles[tris + 5] = vert + xSize + 2;

                vert++;
                tris += 6;
            }
            vert++;
        }
    }

    void UpdateMesh(){
        mesh.Clear();
        mesh.vertices = vertices;
        mesh.triangles = triangles;
        mesh.RecalculateNormals();

// update collider?
        meshCollider.sharedMesh = mesh;

    }

    // Update is called once per frame
    void Update()
    {
        timer += Time.deltaTime;
        
         if(timer > 10f){
            CreateShape(0f);
            UpdateMesh();
        }
        else if(timer > 5f){
            done = true;
            CreateShape(2f);
            UpdateMesh();
        }


    }

    void OnDrawGizmos(){

    }
}