vertices in current camera view

Questions & Answers
1

Hi,

New to Unity. Trying to get the list vertices for each object in the camera view. But not getting the correct result. Using bounding check i.e.

 Vector3 tmp_screen_point = cam.WorldToViewportPoint(transform.TransformPoint(verts[vert]));
                if (tmp_screen_point.z > 0 && (tmp_screen_point.x > 0 && tmp_screen_point.x < 1) && (tmp_screen_point.y > 0 && tmp_screen_point.y < 1))

and Ray cast method (Rays from the Camera). Using Raycast to exclude occluded vertices. Here is my code snippet:

 void Start()
    {   
        
        //Get the list of all active objetcs in the scene
        MeshFilter[] object_mesh_list = FindObjectsOfType<MeshFilter>();
        Camera cam = GameObject.Find("Main Camera").GetComponent<Camera>();
        Vector3 camera_position = cam.transform.position;
        Transform obj = transform;
        //Debug.Log(camera_position);
        RaycastHit ray_hit = new RaycastHit();
        for (int i = 0; i < object_mesh_list.Length; i++)
        {
            Mesh obj_mesh = object_mesh_list*.mesh;*

Vector3[] verts = obj_mesh.vertices;
List in_frame_verts_raycast = new List();
List in_frame_verts_bound = new List();

for (int vert = 0; vert < verts.Length; vert++)
{

//Bounding Method
Vector3 tmp_screen_point = cam.WorldToViewportPoint(transform.TransformPoint(verts[vert]));
if (tmp_screen_point.z > 0 && (tmp_screen_point.x > 0 && tmp_screen_point.x < 1) && (tmp_screen_point.y > 0 && tmp_screen_point.y < 1))
{
in_frame_verts_bound.Add(verts[vert]);
}

//Camrea Ray cast method
Ray ray = cam.ViewportPointToRay(cam.WorldToViewportPoint(transform.TransformPoint(verts[vert])));
if (Physics.Raycast(ray, out ray_hit))
{
in_frame_verts_raycast.Add(verts[vert]);
}
}

Debug.Log(“Raycast Method = Gameobject " + object_mesh_list*.gameObject.name + " has total of: " + verts.Length.ToString() + " vertice and " + in_frame_verts_raycast.Count.ToString() + " are visible to camera”);
Debug.Log("Bound Method = Gameobject " + object_mesh_list.gameObject.name + " has total of: " + verts.Length.ToString() + " vertice and " + in_frame_verts_bound.Count.ToString() + " are visible to camera");*

}

}
and following screen shots show the output. Ray-cast method seems to working but not correct. Only 3 vertices of the quad are visible but it says all 4 are visible.
Imag1:
[157220-1-1.png|157220]
Now rotate camera and resits no vertices are visible.
[157221-2-1.jpg*|157221]*
–Thanks
any suggestion or pointer to fix the issue.
*
*

2

This piece in your code makes no sense:

transform.TransformPoint(verts[vert]))

The vertices are defined in local space of the object where the renderer / MeshFilter is attached to. You treat them as if they belong to the object this script is attached to. So your positions are all over the place.

You have to use:

object_mesh_list*.transform.TransformPoint(verts[vert]))*

Also note that you should not use the mesh property as even reading that property will instantiate the mesh for this MeshFilter. This creates a lot of garbage and also could breaks batching. You should use the “sharedMesh” property.