percentage.cs

    //return visible percentage of object from camera 
    public float GetVisiblePercentage(Bounds bounds, Camera cam)
    {
        float totalVolume = bounds.size.x * bounds.size.y * bounds.size.z;

        float visibleVolume = 0f;
        Plane[] planes = GeometryUtility.CalculateFrustumPlanes(cam);
        for (int i = 0; i < planes.Length; i++)
        {
            visibleVolume += Mathf.Max(0f, Vector3.Dot(planes[i].normal, bounds.max - cam.transform.position));
        }

        float visiblePercentage = visibleVolume / totalVolume * 100f;
        return visiblePercentage;
    }