Question How to deform mesh and mesh collider with another collider

Hi, I am trying to make an trench there is a ground which has mesh and mesh collider i want to make an dent which is same size with trench trench will have box collider. i did with terrain but i couldn't make with mesh. I was thinking i can make a dent with collision points. I am having problem with setting triangles

 

Mesh manipulation is very complicated. As you would need to recreate an array of all the verts, triangles, and UVs, then modify the verts where you want them, and then reapply the mesh.

This an example of just 5 vertices:

Code (CSharp):

1. void Start()
2. {
3.     mesh = new Mesh();
4.     GetComponent<MeshFilter>().mesh = mesh;
5.  
6.     CreateMesh();
7.     UpdateMesh();
8. }
9.  
10. void CreateMesh()
11. {
12.     verts = new Vector3[5];
13.     verts[0] = leftBottom;
14.     verts[1] = leftTop;
15.     verts[2] = center;
16.     verts[3] = rightTop;
17.     verts[4] = rightBottom;
18.  
19.     tris = new int[12];
20.     tris[0] = 0;
21.     tris[1] = 1;
22.     tris[2] = 2;
23.     tris[3] = 1;
24.     tris[4] = 3;
25.     tris[5] = 2;
26.     tris[6] = 3;
27.     tris[7] = 4;
28.     tris[8] = 2;
29.     tris[9] = 4;
30.     tris[10] = 0;
31.     tris[11] = 2;
32.  
33.     uvs = new Vector2[5];
34.     uvs[0] = new Vector2(0, 0);
35.     uvs[1] = new Vector2(0, 2);
36.     uvs[2] = new Vector2(1, 1);
37.     uvs[3] = new Vector2(2, 2);
38.     uvs[4] = new Vector2(2, 0);
39. }
40.  
41. public void UpdateMesh()
42. {
43.     mesh.Clear();
44.  
45.     mesh.vertices = verts;
46.     mesh.triangles = tris;
47.  
48.     mesh.uv = uvs;
49.     mesh.RecalculateNormals();
50. }

 

I was afraid of that . I subdivided my plane to 1000 polygon. Instead of creating new vertices i modify vertices that inside of the box collider