temperature affected by latitude, non-linearly

ReadMe.md

@@ -23,4 +23,7 @@ Using the heightmap generator from here: https://github.com/TangentFoxy/heightma
 - [ ] Do all terrain generation within a radius check so unnecessary work isn't done and discarded.
   - [ ] Terrain generation steps should happen within a single loop wherever possible?
 
+## Reference
+- Out of 52 seeds randomly tested, the current code creates a temperature range between -80.64 and 33.78 C.
+
 (Tasks/Issues are stored in the ReadMe instead of using a webUI issue tracker due to how using such a tracker negatively influences portability of the project.)

src/lib/running_average.lua

@@ -0,0 +1,27 @@
+local running_average = {
+  trackers = {}
+}
+
+local trackers = running_average.trackers
+
+running_average.track = function(name, value)
+  if not trackers[name] then
+    trackers[name] = { running_total = 0, count = 0, }
+  end
+  local track = trackers[name]
+
+  track.running_total = track.running_total + value
+  track.count = track.count + 1
+
+  return track.running_total / track.count
+end
+
+running_average.average = function(name)
+  return trackers[name] and trackers[name].running_total / trackers[name].count
+end
+
+running_average.count = function(name)
+  return trackers[name] and trackers[name].count
+end
+
+return running_average

src/main.lua

@@ -3,6 +3,7 @@ math.randomseed(os.time())
 local map_generator = require "map_nextgen"
 local lovebird = require "lib.lovebird"
 local lume = require "lib.lume"
+local running_average = require "lib.running_average"
 local simplex_map = require "lib.simplex_map"
 
 local map
@@ -11,7 +12,8 @@ love.load = function()
   map = map_generator.generate()
   map.temperature.min = simplex_map.min(map.temperature)
   map.temperature.max = simplex_map.max(map.temperature)
-  print("Temperature Range", map.temperature.min, map.temperature.max)
+  print("Min Temperature", map.temperature.min, "Average", running_average.track("minT", map.temperature.min))
+  print("Max Temperature", map.temperature.max, "Average", running_average.track("maxT", map.temperature.max))
 
   -- if true then return end
 

src/map_nextgen.lua

@@ -102,6 +102,11 @@ local generate = function()
         else
           temperature = temperature + altitude / 1000 -- -1 C / km (deep water adjustment)
         end
+        -- modify temperature by latitude
+        local polar_distance = math.abs(y - (map.size / 2))^1.1 -- experimenting with slight non-linearity
+        local max_temperature_delta = 40
+        temperature = temperature - (polar_distance / map.size * 2 * max_temperature_delta)
+        -- 'save' temperature changes
         map.temperature[x][y] = temperature
 
         -- choose biome