PositionViewer/Assets/Scripts/Controllers/ShowMousePosition.cs

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

public class ShowMousePosition : MonoBehaviour
{
    public GameObject mousePointer;
    // Start is called before the first frame update
    void Start()
    {

    }

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

        mousePointer.transform.position = snapPosition(getWorldPoint());
    }

    public Vector3 getWorldPoint()
    {
        Camera cam = GetComponent<Camera>();
        Ray ray = cam.ScreenPointToRay(Input.mousePosition);
        RaycastHit hit;
        if(Physics.Raycast(ray, out hit)) {
            return hit.point;
        }
        return Vector3.zero;
    }

    public Vector3 snapPosition(Vector3 original)
    {
        Vector3 snapped;
        snapped.x = Mathf.Floor(original.x + 0.5f);
        snapped.y = Mathf.Floor(original.y + 0.5f);
        snapped.z = Mathf.Floor(original.z + 0.5f);
        return snapped;
    }
}