mods/rp_jewels/mapgen.lua

   1 -- Generate jewel ore.
   2
   3 -- Jewel ore generated in birch tree nodes in the giga tree decorations
   4 -- in the Deep Forest biome.
   5 -- The algorithm uses LVM to imitate Minetest's scatter ores,
   6 -- since ores in Minetest are generated after decorations.
   7
   8 -- Fields of the original ore definition:
   9 local clust_scarcity = 11*11*11
  10 local clust_num_ores = 3
  11 local clust_size = 6
  12 local y_min = 0
  13
  14 -- Helper variables
  15 local gigatree_decoration_id = minetest.get_decoration_id("rp_default:gigatree")
  16 local biome_y
  17 local biome_exists
  18 if minetest.registered_biomes["Deep Forest"] then
  19    biome_y = minetest.registered_biomes["Deep Forest"].y_min
  20    biome_exists = true
  21 else
  22    biome_y = tonumber(minetest.get_mapgen_setting("water_level")) or 1
  23    biome_exists = false
  24 end
  25
  26 local lvm_buffer = {}
  27
  28 local c_birch = minetest.get_content_id("rp_default:tree_birch")
  29 local c_jewel_ore = minetest.get_content_id("rp_jewels:jewel_ore")
  30
  31 -- Generation algorithm:
  32 do
  33
  34         -- Helper function to find a random minimum/maxium range of length clust_size.
  35         -- Returned numbers are offsets.
  36         local rnd_minmax = function(pr)
  37                 local min = pr:next(- clust_size + 1, 0)
  38                 local max = min + (clust_size - 1)
  39                 return min, max
  40         end
  41
  42         minetest.set_gen_notify({decoration=true}, {gigatree_decoration_id})
  43         minetest.register_on_generated(function(minp, maxp, blockseed)
  44                 if maxp.y < y_min then
  45                         return
  46                 end
  47                 local ores_in_mapblock = {}
  48                 local pr = PseudoRandom(blockseed)
  49                 local deco_ok = true
  50                 if gigatree_decoration_id then
  51                         -- Was a giga tree was found anywhere in generated area?
  52                         local mgobj = minetest.get_mapgen_object("gennotify")
  53                         local deco = mgobj["decoration#"..gigatree_decoration_id]
  54                         deco_ok = deco and #deco > 0
  55                 end
  56                 if deco_ok then
  57                         -- This code tries to imitate scatter ores in Minetest
  58                         local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
  59                         local area = VoxelArea:new({MinEdge=emin, MaxEdge=emax})
  60                         local data = vm:get_data(lvm_buffer)
  61                         -- Interate through all nodes and place jewel ore in birch tree nodes
  62                         -- with a low chance (1/clust_scarcity)
  63                         for z=minp.z, maxp.z do
  64                         for y=math.max(y_min, minp.y), maxp.y do
  65                         for x=minp.x, maxp.x do
  66                                 local p_pos = area:index(x,y,z)
  67                                 if data[p_pos] == c_birch then
  68                                         local bdata, bname
  69                                         if biome_exists then
  70                                                 bdata = minetest.get_biome_data({x=x,y=math.max(y, biome_y),z=z})
  71                                                 bname = minetest.get_biome_name(bdata.biome)
  72                                         end
  73                                         if ((not biome_exists) or (bname == "Deep Forest")) and pr:next(1, clust_scarcity) == 1 then
  74                                                 data[p_pos] = c_jewel_ore
  75                                                 table.insert(ores_in_mapblock, {x=x,y=y,z=z})
  76                                         end
  77                                 end
  78                         end
  79                         end
  80                         end
  81                         -- If jewel ore was placed in the first phase, also place additional near the initial ore
  82                         for o=1, #ores_in_mapblock do
  83                                 local start_ore = ores_in_mapblock[o]
  84                                 for n=1, clust_num_ores do
  85                                         local ore = {}
  86                                         local axes = {"z","y","x"}
  87                                         for a=1, #axes do
  88                                                 local ax = axes[a]
  89                                                 -- New ores are placed within a randomly positioned bounding box
  90                                                 -- of size clust_size^3 around the initial ore
  91                                                 ore[ax] = start_ore[ax] + pr:next(rnd_minmax(pr))
  92                                                 -- Make sure we stay within minp, maxp
  93                                                 if ore[ax] < minp[ax] then
  94                                                         ore[ax] = minp[ax]
  95                                                 elseif ore[ax] > maxp[ax] then
  96                                                         ore[ax] = maxp[ax]
  97                                                 end
  98                                         end
  99                                         local p_pos = area:index(ore.x, ore.y, ore.z)
 100                                         -- The new random pos must also be a birch tree to generate a jewel ore
 101                                         if data[p_pos] == c_birch then
 102                                                 data[p_pos] = c_jewel_ore
 103                                         end
 104                                 end
 105                         end
 106                         -- Only write back to map when any ore was actually placed
 107                         if #ores_in_mapblock > 0 then
 108                                 vm:set_data(data)
 109                                 vm:write_to_map()
 110                         end
 111                 end
 112         end)
 113 end