void SetupObjectsSectors() {
_sectorsMinNumPos = IsoUtils.Vec2From(float.MaxValue);
_sectorsMaxNumPos = IsoUtils.Vec2From(float.MinValue);
var visibles_iter = _visibles.GetEnumerator();
while ( visibles_iter.MoveNext() ) {
var iso_internal = visibles_iter.Current.Internal;
iso_internal.MinSector = IsoUtils.Vec3DivFloor(iso_internal.ScreenRect.min, _sectorsSize);
iso_internal.MaxSector = IsoUtils.Vec3DivCeil (iso_internal.ScreenRect.max, _sectorsSize);
_sectorsMinNumPos = IsoUtils.Vec3Min(_sectorsMinNumPos, iso_internal.MinSector);
_sectorsMaxNumPos = IsoUtils.Vec3Max(_sectorsMaxNumPos, iso_internal.MaxSector);
}
_sectorsNumPosCount = _sectorsMaxNumPos - _sectorsMinNumPos;
}