110 lines
3.1 KiB
Lua
110 lines
3.1 KiB
Lua
--- Procedural generation methods
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function init_mapgen()
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uid_seed = 2229 -- arbitrarily chosen number
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block_size = 64
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biome_size = 128
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-- Metadata for different biomes
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-- frequencies don't have to add up to 100, but they should by convention
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--
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-- Sprites are:
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-- * 2 - grass
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-- * 3 - bush
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-- * 4 - tree
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-- * 5 - red flowers
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-- * 6 - pink flowers
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-- * 7 - mushrooms
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-- * 8 - big mushroom
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-- * 9 - sand
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-- * 10 - cactus with flower
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-- * 11 - pebbles
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-- * 12 - rock
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-- * 13 - cactus
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biome_data = {
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grassland = {
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biome_frequency = 75,
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tile_frequencies = { {40, 2}, {28, 5}, {28, 6}, {3, 3}, {1, 4} }
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},
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forest = {
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biome_frequency = 20,
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tile_frequencies = { {60, 2}, {20, 4}, {5, 3}, {5, 5}, {4, 7}, {5, 6}, {1, 8} }
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},
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desert = {
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biome_frequency = 5,
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tile_frequencies = { {80, 9}, {10, 11}, {6, 13}, {3, 12}, {1, 10} },
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}
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}
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init_biomes()
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end
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function init_biomes()
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-- this is the frequency list for the biomes themselves
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biome_metadata = {}
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for k,v in pairs(biome_data) do
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-- add the biome's name N times to the biome metadata 'hat'
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for i=1,v["biome_frequency"] do
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add(biome_metadata, k)
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end
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build_biome(k, v)
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end
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end
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-- build the lookup table for a given biome, based on the biome_meta data for
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-- that string.
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function build_biome(biome_name, data)
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local meta_frequencies = data["tile_frequencies"]
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local tile_lookup = {}
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for i=1,#meta_frequencies do
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local tuple = meta_frequencies[i]
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for j=1,tuple[1] do
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add(tile_lookup, tuple[2])
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end
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end
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data["tile_lookup"] = tile_lookup
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end
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-- generates a unique identifier for a position
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-- uses srand() and rand() to get an unpredictable value (is this too slow?)
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function generate_uid(pos)
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srand((pos[1] + uid_seed) * (pos[2] + (uid_seed^2)))
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return flr(rnd(-1))
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end
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-- determines which biome a given world map position should be,
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-- returns the object out of the biome_data table
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function get_biome(pos)
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local biome_pos = {flr(pos[1] / biome_size), flr(pos[2] / biome_size)}
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local uid = generate_uid(biome_pos)
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local biome_name = biome_metadata[(uid % #biome_metadata) + 1]
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return biome_data[biome_name]
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end
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-- determine what sprite to render for a given position.
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-- todo: this needs the ability to have a list of 'changed' tiles to check against.
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function get_tile(pos)
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local biome = get_biome(pos)
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local uid = generate_uid(pos)
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return biome["tile_lookup"][(uid % #biome["tile_lookup"]) + 1]
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end
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-- generate the map and writes to the map area from 0 - block_size,
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-- assuming 'start' as the top-left corner of the map area to generate.
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-- writes block_size x block_size tiles
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-- after a call to generate_map you should always center the camera/player over the map, i.e.
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-- camera at { (block_size / 2) - 8, (block_size / 2) - 8 }
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function generate_map(start)
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for x=0,block_size-1 do
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for y=0,block_size-1 do
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mset(x, y, get_tile({start[1]+x, start[2]+y}))
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end
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end
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end
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