pub struct Config {
    pub sea_level: f32,
    pub mountain_scale: f32,
    pub snow_temp: f32,
    pub tropical_temp: f32,
    pub desert_temp: f32,
    pub desert_hum: f32,
    pub forest_hum: f32,
    pub jungle_hum: f32,
    /// Rainfall (in meters) per chunk per minute.  Default is set to make it approximately
    /// 1 m rainfall / year uniformly across the whole land area, which is the average rainfall
    /// on Earth.
    pub rainfall_chunk_rate: f32,
    /// Roughness coefficient is an empirical value that controls the rate of energy loss of water
    /// in a river.  The higher it is, the more water slows down as it flows downhill, which
    /// consequently leads to lower velocities and higher river area for the same flow rate.
    ///
    /// See https://wwwrcamnl.wr.usgs.gov/sws/fieldmethods/Indirects/nvalues/index.htm.
    ///
    /// The default is set to over 0.06, which is pretty high but still within a reasonable range for
    /// rivers.  The higher this is, the quicker rivers appear, and since we often will have high
    /// slopes we want to give rivers as much of a chance as possible.  In the future we can set
    /// this dynamically.
    ///
    /// NOTE: The values in the link are in seconds / (m^(-1/3)), but we use them without
    /// conversion as though they are in minutes / (m^(-1/3)).  The idea here is that our clock
    /// speed has time go by at approximately 1 minute per second, but since velocity depends on
    /// this parameter, we want flow rates to still "look" natural at the second level.  The way we
    /// are cheating is that we still allow the refill rate (via rainfall) of rivers and lakes to
    /// be specified as though minutes are *really* minutes.  This reduces the amount of water
    /// needed to form a river of a given area by 60, but hopefully this should not feel too
    /// unnatural since the refill rate is still below what people should be able to perceive.
    pub river_roughness: f32,
    /// Maximum width of rivers, in terms of a multiple of the horizontal chunk size.
    ///
    /// Currently, not known whether setting this above 1.0 will work properly.  Please use with
    /// care!
    pub river_max_width: f32,
    /// Minimum height at which rivers display.
    pub river_min_height: f32,
    /// Rough desired river width-to-depth ratio (in terms of horizontal chunk width / m, for some
    /// reason).  Not exact.
    pub river_width_to_depth: f32,
}

pub const CONFIG: Config = Config {
    sea_level: 140.0,
    mountain_scale: 2048.0,
    snow_temp: -0.6,
    tropical_temp: 0.2,
    desert_temp: 0.6,
    desert_hum: 0.15,
    forest_hum: 0.5,
    jungle_hum: 0.85,
    rainfall_chunk_rate: 1.0 / 512.0,
    river_roughness: 0.06125,
    river_max_width: 2.0,
    river_min_height: 0.25,
    river_width_to_depth: 1.0,
};