if (y > y_end)
{
    if (sprite_index != spr_dunes_10_pebbles_fall)
    {
        sprite_index = spr_dunes_10_pebbles_fall
        image_index = 0
        vspeed = 0
    }
    else if on_animation_end()
    {
        image_index = image_number - 1
        image_speed = 0
        if (!alarm[0])
            alarm[0] = 10
    }
    return;
}
vspeed += 0.1