RedMew/map_gen/maps/danger_ores/modules/water.lua

local Perlin = require 'map_gen.shared.perlin_noise'
local seed_provider = require 'map_gen.maps.danger_ores.modules.seed_provider'
local b = require 'map_gen.shared.builders'

local perlin_noise = Perlin.noise

return function(config)
    local scale = config.water_scale or 1 / 96
    local water_threshold = config.water_threshold or 0.5
    local deepwater_threshold = config.deepwater_threshold or 0.55

    local scale_function
    if type(scale) == 'function' then
        scale_function = scale
    else
        scale_function = function()
            return scale
        end
    end

    local no_water_shape = config.no_water_shape or b.circle(96)
    local seed = config.water_seed or seed_provider()

    return function(x, y, world)
        if no_water_shape(x, y, world) then
            return false
        end

        local s = scale_function(x, y, world)

        local water_noise = perlin_noise(x * s, y * s, seed)
        if water_noise >= deepwater_threshold then
            return 'deepwater'
        elseif water_noise >= water_threshold then
            return 'water'
        end

        return false
    end
end