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

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