if (_music_fade)
{
    if (global.flag[20] == 1)
    {
        if (_music_alt[0] == -4)
        {
            _music_alt[0] = snd_init("shop_3.ogg");
            _music_alt[1] = mus_loop_ext(_music_alt[0], global.flag[17], 0.5);
        }
    }
    else if (global.flag[20] == 2)
    {
        if (!_music_fade_out)
        {
            _music_fade_out = true;
            mus_volume(_music_alt[1], 0, 30);
        }
    }
    else if (global.flag[20] == 3)
    {
        _music_fade = false;
        mus_volume(global.currentsong[1], 1, 30);
    }
}