diff --git a/src/main.lua b/src/main.lua
index 93a9037..29a000d 100644
--- a/src/main.lua
+++ b/src/main.lua
@@ -1,139 +1,11 @@
-local heightmap = require "lib.heightmap"
+local map_generator = require "map_generator"
 local lovebird = require "lib.lovebird"
 local lume = require "lib.lume"
 
-local map = {}
-
-local biomes = {
-  -- [5] = {
-  --   name = "ocean",
-  --   altitude = {min = 0, max = 0.2}, -- bottom of world is the only part that matters
-  --   temperature = {min = 0, max = 1},
-  --   humidity = {min = 0, max = 1},
-  --   color = {0, 0, 0.67, 1},
-  -- },
-  -- [6] = {
-  --   name = "beach",
-  --   altitude = {min = 0.2, max = 0.205}, -- just above ocean
-  --   temperature = {min = 0, max = 1},
-  --   humidity = {min = 0, max = 0.8}, -- excluding upper humidity for swamp
-  --   color = {1, 1, 0.33, 1}, -- brighter yellow to distinguish from sand
-  -- },
-  -- [8] = {
-  --   name = "swamp", -- fun idea, but generates between ocean and water too often?
-  --   altitude = {min = 0, max = 1},
-  --   temperature = {min = 0.5, max = 1},
-  --   humidity = {min = 0.95, max = 1},
-  --   color = {0, 0.5, 0.33, 1},
-  -- },
-  -- [10] = {
-  --   name = "water",
-  --   altitude = {min = 0, max = 0.9}, -- top excluded because it should've gone downhill
-  --   temperature = {min = 0.1, max = 0.9}, -- bottom should be ice, top should evaporate
-  --   humidity = {min = 0.8, max = 1}, -- only the wettest places
-  --   color = {0, 0, 1, 1},
-  -- },
-  -- [20] = {
-  --   name = "sand",
-  --   altitude = {min = 0.2, max = 0.9}, -- top falls down, bottom is underwater
-  --   temperature = {min = 0, max = 1},
-  --   humidity = {min = 0, max = 0.2}, -- only where dry makes more sense for a desert
-  --   color = {1, 1, 0, 1},
-  -- },
-  -- [30] = {
-  --   name = "grass",
-  --   altitude = {min = 0.3, max = 0.9}, -- top of the world not enough air, bottom too wet / leaving space for others
-  --   temperature = {min = 0.2, max = 0.8}, -- not very sensitive to temperature
-  --   humidity = {min = 0.2, max = 0.6}, -- not very sensitive to humidity; but excluded from the worst
-  --   color = {0, 1, 0, 1},
-  -- },
-  -- [40] = {
-  --   name = "trees",
-  --   altitude = {min = 0.4, max = 0.7}, -- more sensitive than grass
-  --   temperature = {min = 0, max = 0.7},
-  --   humidity = {min = 0.3, max = 0.8}, -- these are not desert trees, they need more water
-  --   color = {0, 0.67, 0, 1},
-  -- },
-  -- [60] = {
-  --   name = "stone",
-  --   altitude = {min = 0, max = 1},
-  --   temperature = {min = 0, max = 1},
-  --   humidity = {min = 0, max = 1},
-  --   color = {0.67, 0.67, 0.67, 1},
-  -- },
-  -- [50] = {
-  --   name = "ice",
-  --   altitude = {min = 0, max = 1},
-  --   temperature = {min = 0, max = 0.01},
-  --   humidity = {min = 0.2, max = 1},
-  --   color = {1, 1, 1, 1},
-  -- },
-  [900] = {
-    name = "deep ocean",
-    altitude = {min = -math.huge, max = -400},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {0, 0, 0.25, 1},
-  },
-  [1000] = {
-    name = "ocean (definition, 0 meters)",
-    altitude = {min = -math.huge, max = 0},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {0, 0, 0.5, 1},
-  },
-  [2000] = {
-    name = "snowline (middle estimate)",
-    altitude = {min = 4000, max = math.huge},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {1, 1, 1, 1},
-  },
-  [2100] = {
-    name = "alpine zone",
-    altitude = {min = 3500, max = math.huge},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {0.8, 0.8, 0.8, 1},
-  },
-  [2200] = {
-    name = "subalpine zone",
-    altitude = {min = 3000, max = math.huge},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {0.67, 0.67, 0.67, 1},
-  },
-  [2300] = {
-    name = "montane zone",
-    altitude = {min = 2500, max = math.huge},
-    temperature = {min = -math.huge, max = math.huge},
-    humidity = {min = -math.huge, max = math.huge},
-    color = {0.67, 0.67, 0.5, 1},
-  },
-}
+local map
 
 love.load = function()
-  map.size = 500
-  map.tile_size = 1
-  map.altitude = heightmap.create(map.size, map.size, -440, 8849) -- meters
-  map.temperature = heightmap.create(map.size, map.size, -89.2, 56.7) -- celsius
-  map.humidity = heightmap.create(map.size, map.size, 18, 3240) -- millimeters rainfall
-
-  local function altitude_ocean_bias(altitude)
-    local bias = 3.5 -- higher -> more ocean
-    local normalized_altitude = (altitude - -400) / (8849 - -440)
-    return -440 + normalized_altitude^bias * (8849 - -440)
-  end
-  local min, max = math.huge, -math.huge
-  for x = 0, map.size do
-    for y = 0, map.size do
-      local value = altitude_ocean_bias(map.altitude[x][y])
-      if value > max then max = value end
-      if value < min then min = value end
-      map.altitude[x][y] = value
-    end
-  end
-  print("Altitude", "Min: ", min, "Max:", max)
+  map = map_generator.generate()
 
   -- if true then return end
 
@@ -165,38 +37,6 @@ love.load = function()
   --   end
   -- end
   -- heightmap.normalize(map.humidity, 18, 3240)
-
-  -- planetizer!
-  local biome_order = {}
-  for order in pairs(biomes) do
-    biome_order[#biome_order + 1] = order
-  end
-  table.sort(biome_order)
-
-  map.terrain = {w = map.size, h = map.size}
-  local radius = (map.size / 2)^2
-  for x = 0, map.size do
-    map.terrain[x] = {}
-    for y = 0, map.size do
-      if lume.distance(x, y, map.size / 2, map.size / 2, true) < radius then
-        -- for _, biome in ipairs(biomes) do
-        for _, order in ipairs(biome_order) do
-          local biome = biomes[order]
-          local altitude = map.altitude[x][y]
-          if altitude >= biome.altitude.min and altitude <= biome.altitude.max then
-            local temperature = map.temperature[x][y]
-            if temperature >= biome.temperature.min and temperature <= biome.temperature.max then
-              local humidity = map.humidity[x][y]
-              if humidity >= biome.humidity.min and humidity <= biome.humidity.max then
-                map.terrain[x][y] = biome.color
-                break
-              end
-            end
-          end
-        end
-      end
-    end
-  end
 end
 
 local camera = {
diff --git a/src/map_generator.lua b/src/map_generator.lua
new file mode 100644
index 0000000..8df32b6
--- /dev/null
+++ b/src/map_generator.lua
@@ -0,0 +1,174 @@
+local heightmap = require "lib.heightmap"
+local lume = require "lib.lume"
+
+local biomes = {
+  -- [5] = {
+  --   name = "ocean",
+  --   altitude = {min = 0, max = 0.2}, -- bottom of world is the only part that matters
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 1},
+  --   color = {0, 0, 0.67, 1},
+  -- },
+  -- [6] = {
+  --   name = "beach",
+  --   altitude = {min = 0.2, max = 0.205}, -- just above ocean
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 0.8}, -- excluding upper humidity for swamp
+  --   color = {1, 1, 0.33, 1}, -- brighter yellow to distinguish from sand
+  -- },
+  -- [8] = {
+  --   name = "swamp", -- fun idea, but generates between ocean and water too often?
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0.5, max = 1},
+  --   humidity = {min = 0.95, max = 1},
+  --   color = {0, 0.5, 0.33, 1},
+  -- },
+  -- [10] = {
+  --   name = "water",
+  --   altitude = {min = 0, max = 0.9}, -- top excluded because it should've gone downhill
+  --   temperature = {min = 0.1, max = 0.9}, -- bottom should be ice, top should evaporate
+  --   humidity = {min = 0.8, max = 1}, -- only the wettest places
+  --   color = {0, 0, 1, 1},
+  -- },
+  -- [20] = {
+  --   name = "sand",
+  --   altitude = {min = 0.2, max = 0.9}, -- top falls down, bottom is underwater
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 0.2}, -- only where dry makes more sense for a desert
+  --   color = {1, 1, 0, 1},
+  -- },
+  -- [30] = {
+  --   name = "grass",
+  --   altitude = {min = 0.3, max = 0.9}, -- top of the world not enough air, bottom too wet / leaving space for others
+  --   temperature = {min = 0.2, max = 0.8}, -- not very sensitive to temperature
+  --   humidity = {min = 0.2, max = 0.6}, -- not very sensitive to humidity; but excluded from the worst
+  --   color = {0, 1, 0, 1},
+  -- },
+  -- [40] = {
+  --   name = "trees",
+  --   altitude = {min = 0.4, max = 0.7}, -- more sensitive than grass
+  --   temperature = {min = 0, max = 0.7},
+  --   humidity = {min = 0.3, max = 0.8}, -- these are not desert trees, they need more water
+  --   color = {0, 0.67, 0, 1},
+  -- },
+  -- [60] = {
+  --   name = "stone",
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 1},
+  --   color = {0.67, 0.67, 0.67, 1},
+  -- },
+  -- [50] = {
+  --   name = "ice",
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0, max = 0.01},
+  --   humidity = {min = 0.2, max = 1},
+  --   color = {1, 1, 1, 1},
+  -- },
+  [900] = {
+    name = "deep ocean",
+    altitude = {min = -math.huge, max = -400},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.25, 1},
+  },
+  [1000] = {
+    name = "ocean (definition, 0 meters)",
+    altitude = {min = -math.huge, max = 0},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.5, 1},
+  },
+  [2000] = {
+    name = "snowline (middle estimate)",
+    altitude = {min = 4000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {1, 1, 1, 1},
+  },
+  [2100] = {
+    name = "alpine zone",
+    altitude = {min = 3500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.8, 0.8, 0.8, 1},
+  },
+  [2200] = {
+    name = "subalpine zone",
+    altitude = {min = 3000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.67, 1},
+  },
+  [2300] = {
+    name = "montane zone",
+    altitude = {min = 2500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.5, 1},
+  },
+}
+
+local function generate()
+  local map = {}
+
+  map.size = 500
+  map.tile_size = 1
+  map.altitude = heightmap.create(map.size, map.size, -440, 8849) -- meters
+  map.temperature = heightmap.create(map.size, map.size, -89.2, 56.7) -- celsius
+  map.humidity = heightmap.create(map.size, map.size, 18, 3240) -- millimeters rainfall
+
+  local function altitude_ocean_bias(altitude)
+    local bias = 3.5 -- higher -> more ocean
+    local normalized_altitude = (altitude - -400) / (8849 - -440)
+    return -440 + normalized_altitude^bias * (8849 - -440)
+  end
+  local min, max = math.huge, -math.huge
+  for x = 0, map.size do
+    for y = 0, map.size do
+      local value = altitude_ocean_bias(map.altitude[x][y])
+      if value > max then max = value end
+      if value < min then min = value end
+      map.altitude[x][y] = value
+    end
+  end
+  print("Altitude", "Min: ", min, "Max:", max)
+
+  -- planetizer!
+  local biome_order = {}
+  for order in pairs(biomes) do
+    biome_order[#biome_order + 1] = order
+  end
+  table.sort(biome_order)
+
+  map.terrain = {w = map.size, h = map.size}
+  local radius = (map.size / 2)^2
+  for x = 0, map.size do
+    map.terrain[x] = {}
+    for y = 0, map.size do
+      if lume.distance(x, y, map.size / 2, map.size / 2, true) < radius then
+        -- for _, biome in ipairs(biomes) do
+        for _, order in ipairs(biome_order) do
+          local biome = biomes[order]
+          local altitude = map.altitude[x][y]
+          if altitude >= biome.altitude.min and altitude <= biome.altitude.max then
+            local temperature = map.temperature[x][y]
+            if temperature >= biome.temperature.min and temperature <= biome.temperature.max then
+              local humidity = map.humidity[x][y]
+              if humidity >= biome.humidity.min and humidity <= biome.humidity.max then
+                map.terrain[x][y] = biome.color
+                break
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+
+  return map
+end
+
+return {
+  generate = generate,
+}