depth = -2000;
_opacity = 0;
_opacity_min = 0;
_opacity_interval = 0;
_opacity_speed = 0;

proceed = function(arg0)
{
    _opacity = _opacity_min;
    _opacity_speed = 0.02 / (arg0 / 30);
    _opacity_min = clamp(_opacity_min + 0.02, 0, 0.33);
};