Initial commit.

mapgen.lua

@@ -0,0 +1,64 @@
+--- Procedural generation methods
+
+function init_mapgen()
+   uid_seed = 1229 -- arbitrarily chosen number
+   block_size = 128
+
+   -- Sprite ratios for different biomes, of the form { "biome_name": {frequency, sprite index} ... } }
+   -- frequencies don't have to add up to 100, but they should by convention
+   --
+   -- Sprites are:
+   --  * 2 - grass
+   --  * 3 - bush
+   --  * 4 - tree
+   --  * 5 - red flowers
+   --  * 6 - pink flowers
+   --  * 7 - mushrooms
+   biomes = { grassland = { {40, 2}, {28, 5}, {28, 6}, {3, 3}, {1, 4} },
+              forest = { {40, 2}, {50, 4}, {5, 3}, {4, 5}, {1, 7} } }
+   
+   build_biome("forest")
+end
+
+-- use biome1
+function build_biome(biome1, biome2, mix)
+   if mix == true then
+   else
+      frequencies = biomes[biome1]
+   end
+
+   -- global variable used for lookup during mapgen
+   biome_lookup = {}
+   for i=1,#frequencies do
+      local tuple=frequencies[i]
+      for j=1,tuple[1] do
+         add(biome_lookup, tuple[2])
+      end
+   end
+end
+
+-- generates a unique identifier for a position
+-- uses srand() and rand() to get an unpredictable value (is this too slow?)
+function generate_uid(pos)
+   srand((pos[1] + uid_seed) * (pos[2] + (uid_seed^2)))
+   return flr(rnd(-1))
+end
+
+-- determine what sprite to render for a given position
+function get_tile(pos)
+   return biome_lookup[(generate_uid(pos) % #biome_lookup) + 1]
+end
+
+-- generate the map and writes to the map area from 0 - block_size,
+-- assuming 'start' as the top-left corner of the map area to generate.
+-- writes block_size x block_size tiles
+-- after a call to generate_map you should always center the camera/player over the map, i.e.
+-- camera at { (block_size / 2) - 8, (block_size / 2) - 8 }
+function generate_map(start)
+   for x=0,block_size-1 do
+      for y=0,block_size-1 do
+         mset(x, y, get_tile({start[1]+x, start[2]+y}))
+      end
+   end
+end
+