control.lua

require("smallRuins")
require("mediumRuins")
require("largeRuins")

local DEBUG = false --used for debug, users should not enable

--function that will return true 'percent' of the time.
function probability(percent)
    return math.random() <= percent
end

script.on_event({defines.events.on_chunk_generated},
    function (e)
        local center = {x=(e.area.left_top.x+e.area.right_bottom.x)/2, y=(e.area.left_top.y+e.area.right_bottom.y)/2}
        if math.abs(center.x) < settings.global["ruins-min-distance-from-spawn"].value and math.abs(center.y) < settings.global["ruins-min-distance-from-spawn"].value then return end --too close to spawn

        if probability(settings.global["ruins-small-ruin-chance"].value) then
            --spawn small ruin
            if DEBUG then
                game.print("A small ruin was spawned at " .. center.x .. "," .. center.y)
            end

            --random variance so they aren't always chunk aligned
            center.x = center.x + math.random(-10,10)
            center.y = center.y + math.random(-10,10)

            spawnSmallRuins(center, e.surface)
        elseif probability(settings.global["ruins-medium-ruin-chance"].value) then
            --spawn medium ruin
            if DEBUG then
                game.print("A medium ruin was spawned at " .. center.x .. "," .. center.y)
            end

            --random variance so they aren't always chunk aligned
            center.x = center.x + math.random(-5,5)
            center.y = center.y + math.random(-5,5)

            spawnMediumRuins(center, e.surface)
        elseif probability(settings.global["ruins-large-ruin-chance"].value) then
            --spawn large ruin
            if DEBUG then
                game.print("A large ruin was spawned at " .. center.x .. "," .. center.y)
            end
            spawnLargeRuins(center, e.surface)
        end
    end
)

script.on_init(
    function()
        math.randomseed(game.surfaces[1].map_gen_settings.seed) --set the random seed to the map seed, so ruins are the same-ish with each generation.
    end
)