Implement multiple biomes.

mapgen.lua

@@ -3,8 +3,9 @@
 function init_mapgen()
    uid_seed = 2229 -- arbitrarily chosen number
    block_size = 64
+   biome_size = 128
 
-   -- Sprite ratios for different biomes, of the form { "biome_name": {frequency, sprite index} ... } }
+   -- Metadata for different biomes
    -- frequencies don't have to add up to 100, but they should by convention
    --
    -- Sprites are:
@@ -14,31 +15,58 @@ function init_mapgen()
    --  * 5 - red flowers
    --  * 6 - pink flowers
    --  * 7 - mushrooms
-   biomes = { grassland = { {40, 2}, {28, 5}, {28, 6}, {3, 3}, {1, 4} },
-              forest = { {55, 2}, {25, 4}, {5, 3}, {5, 5}, {5, 7}, {5, 6} },
-            }
-   
-   build_biome("forest")
+   --  * 8 - big mushroom
+   --  * 9 - sand
+   --  * 10 - cactus with flower
+   --  * 11 - pebbles
+   --  * 12 - rock
+   --  * 13 - cactus
+   biome_data = {
+      grassland = {
+         biome_frequency = 75,
+         tile_frequencies = { {40, 2}, {28, 5}, {28, 6}, {3, 3}, {1, 4} }
+      },
+      forest = {
+         biome_frequency = 20,
+         tile_frequencies = { {60, 2}, {20, 4}, {5, 3}, {5, 5}, {4, 7}, {5, 6}, {1, 8} }
+      },
+      desert = {
+         biome_frequency = 5,
+         tile_frequencies = { {80, 9}, {10, 11}, {6, 13}, {3, 12}, {1, 10} },
+      }
+   }
+
+   init_biomes()
 end
 
--- use biome1 if mix == false
-function build_biome(biome1, biome2, mix)
-   if mix == true then
-   else
-      frequencies = biomes[biome1]
-   end
+function init_biomes()
+   -- this is the frequency list for the biomes themselves
+   biome_metadata = {}
 
-   -- global variable used for lookup during mapgen
-   -- build_biome() writes the biome_lookup table such
-   -- that biome_lookup[uid] returns a sprite index,
-   -- weighted by the frequency information for current biome.
-   biome_lookup = {}
-   for i=1,#frequencies do
-      local tuple=frequencies[i]
+   for k,v in pairs(biome_data) do
+      -- add the biome's name N times to the biome metadata 'hat'
+      for i=1,v["biome_frequency"] do
+         add(biome_metadata, k)
+      end
+
+      build_biome(k, v)
+   end
+end
+
+-- build the lookup table for a given biome, based on the biome_meta data for
+-- that string.
+function build_biome(biome_name, data)
+   local meta_frequencies = data["tile_frequencies"]
+   local tile_lookup = {}
+
+   for i=1,#meta_frequencies do
+      local tuple = meta_frequencies[i]
       for j=1,tuple[1] do
-         add(biome_lookup, tuple[2])
+         add(tile_lookup, tuple[2])
       end
    end
+
+   data["tile_lookup"] = tile_lookup
 end
 
 -- generates a unique identifier for a position
@@ -48,9 +76,22 @@ function generate_uid(pos)
    return flr(rnd(-1))
 end
 
--- determine what sprite to render for a given position
+-- determines which biome a given world map position should be,
+-- returns the object out of the biome_data table
+function get_biome(pos)
+   local biome_pos = {flr(pos[1] / biome_size), flr(pos[2] / biome_size)}
+   local uid = generate_uid(biome_pos)
+   local biome_name = biome_metadata[(uid % #biome_metadata) + 1]
+   return biome_data[biome_name]
+end
+
+-- determine what sprite to render for a given position.
+-- todo: this needs the ability to have a list of 'changed' tiles to check against.
 function get_tile(pos)
-   return biome_lookup[(generate_uid(pos) % #biome_lookup) + 1]
+   local biome = get_biome(pos)
+   local uid = generate_uid(pos)
+
+   return biome["tile_lookup"][(uid % #biome["tile_lookup"]) + 1]
 end
 
 -- generate the map and writes to the map area from 0 - block_size,