Unity C# generated mesh is offset why is it not in the correct location?

Question

I am attempting to generate a mesh in unity from script. The mesh is generated by raycasting out in a particular direction. Then getting the vertices from the hit point or from where the ray terminates. The mesh generates fine and is working well, however the mesh generates approximately 5 to 10 unity units above the location of the object with the attached script. I will attach me script below.

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

public class Torch : MonoBehaviour {

    public GameObject  lightmeshholder;

    private int RaysToShoot = 128;
    private float distance = 50;
    private Vector3[] vertices;
    private Vector2[] vertices2d;
    private int[] triangles;

    private Mesh mesh;

    private Texture2D texture;
    private int screenwidth;
    private int screenheight;
    private int grab = 0;

    private RaycastHit hit;


    // Use this for initialization
    void Start () {
    screenwidth = Screen.width;
    screenheight = Screen.height;
    texture = new Texture2D (screenwidth, screenheight, TextureFormat.RGB24, false);

    vertices = new Vector3[RaysToShoot];
    vertices2d = new Vector2[RaysToShoot];
    triangles = new int[(RaysToShoot) +1 ];

    mesh= lightmeshholder.GetComponent<MeshFilter>().mesh;

    }

    // Update is called once per frame
    void Update () {

        float angle =0;

            for(int i=0;i<RaysToShoot;i++){

                        float x = Mathf.Sin(0);
                        x=-5;
            if(Input.GetKey(KeyCode.P)){
                    x = 5;
            }
                        float y = Mathf.Cos(angle);
            if (angle <= 90){
                        angle += 2*Mathf.PI/RaysToShoot;
            }

            Vector3 dir = new Vector3(x,y,0);
        if (Physics.Raycast (this.transform.position, dir,out hit, distance)) 
        {
                Debug.DrawLine (this.transform.position, hit.point,new Color(1,1,0,1));
            Vector3 tmp = lightmeshholder.transform.InverseTransformPoint(hit.point);
            vertices2d[i] = new Vector2(tmp.x,tmp.y);

            }else{
            Vector3 tmp = lightmeshholder.transform.InverseTransformPoint(this.transform.position + dir*distance);
            vertices2d[i] = new Vector2(tmp.x,tmp.y);
            Debug.DrawLine(this.transform.position,dir * distance,Color.red,0); 
            }



        }

        // build mesh

    Vector2[] uvs = new Vector2[vertices2d.Length +1];
    Vector3[] newvertices = new Vector3[vertices2d.Length+1];


    for (int n = 0; n<newvertices.Length-1 ;n++) 
    {


            if(n==0){
            newvertices[0]=this.transform.position; 
                newvertices[1] = vertices2d[0];
                uvs[0] = new Vector2(this.transform.position.x,this.transform.position.y);
                uvs[1] = vertices2d[0];
            }else{
            newvertices[n+1] = vertices2d[n];   
                uvs[n+1] = vertices2d[n];
            }

            if(n==0){
                triangles[0] = 0;   
                triangles[1] = 1;
                triangles[2] = 2;
            }else if(n<newvertices.Length/3){
                triangles[n*3] = 0; 
                triangles[1+n*3] = n+1;
                triangles[2+n*3] = n+2;
            }

    }
        Mesh mesh = new Mesh(); 
        GetComponent<MeshFilter>().mesh = mesh; 
        mesh.Clear();
        mesh.vertices = newvertices;        
        mesh.uv = uvs;  
        mesh.triangles = triangles;
        mesh.RecalculateNormals();          
    }
}  

Answer 1

When you are assigning vertices back to mesh they are calculated in local coordinates with respect to object root. So if you want to bring it back "where it should be" process them with .TransformPoint() call to get proper offsets. This should fix your problem with them being in different location than you expect. I had same problem.

Answer 2

The hitpoints you're getting from the raycasts are global. You can either:

1) Make sure the mesh is in a gameobject that is positioned at 0,0,0. Whenever I create a dynamic mesh based on ray hitpoints I usually create a new parent-less gameobject at 0,0,0 and add the mesh to it. (instead of getting a container GameObject externally)

2) Call lightmeshholder.transform.InverseTransformPoint on the hitpoints from the raycast before building the mesh