private List <GlyphSphere> enableOnlyCloseGlyphs()
    {
        GPSLocation[] closeBounds = currentPlayerLocation.calculateLatLongBoundingBox(MAX_RENDER_DISTANCE);

        List <GlyphSphere> activeSpheres = new List <GlyphSphere> ();

        for (int i = 0; i < glyphSpheres.Count; i++)
        {
            GlyphSphere sphere                    = glyphSpheres [i];
            GPSLocation glyphLocation             = glyphSpheres [i].getGlyph().GetGpsLocation();
            bool        glyphSphereIsInsideBounds = glyphLocation.isInsideBounds(closeBounds);
            Debug.LogError("Bounds : " + sphere.getGlyph().GetGlyphId() + " " + glyphSphereIsInsideBounds);
            sphere.setSphereActive(glyphSphereIsInsideBounds);

            if (sphere.isSphereActive())
            {
                activeSpheres.Add(sphere);
            }
        }

        return(activeSpheres);
    }