Camas/mods/jewels/mapgen.lua

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-- Generate jewel ore.
-- Jewel ore generated in birch tree nodes in the giga tree decorations
-- in the Deep Forest biome.
-- The algorithm uses LVM to imitate Minetest's scatter ores,
-- since ores in Minetest are generated after decorations.
-- Fields of the original ore definition:
local clust_scarcity = 11*11*11
local clust_num_ores = 3
local clust_size = 6
local y_min = 0
-- Helper variables
local gigatree_decoration_id = minetest.get_decoration_id("default:gigatree")
local biome_y = minetest.registered_biomes["Deep Forest"].y_min
local lvm_buffer = {}
local c_birch = minetest.get_content_id("default:tree_birch")
local c_jewel_ore = minetest.get_content_id("jewels:jewel_ore")
-- Generation algorithm:
if gigatree_decoration_id then
-- Helper function to find a random minimum/maxium range of length clust_size.
-- Returned numbers are offsets.
local rnd_minmax = function(pr)
local min = pr:next(- clust_size + 1, 0)
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local max = min + (clust_size - 1)
return min, max
end
minetest.set_gen_notify({decoration=true}, {gigatree_decoration_id})
minetest.register_on_generated(function(minp, maxp, blockseed)
if maxp.y < y_min then
return
end
local ores_in_mapblock = {}
local pr = PseudoRandom(blockseed)
local mgobj = minetest.get_mapgen_object("gennotify")
local deco = mgobj["decoration#"..gigatree_decoration_id]
-- If a giga tree was found anywhere in generated area, activate generation
if deco and #deco > 0 then
-- This code tries to imitate scatter ores in Minetest
local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
local area = VoxelArea:new({MinEdge=emin, MaxEdge=emax})
local data = vm:get_data(lvm_buffer)
-- Interate through all nodes and place jewel ore in birch tree nodes
-- with a low chance (1/clust_scarcity)
for z=minp.z, maxp.z do
for y=math.max(y_min, minp.y), maxp.y do
for x=minp.x, maxp.x do
local p_pos = area:index(x,y,z)
if data[p_pos] == c_birch then
local bdata = minetest.get_biome_data({x=x,y=math.max(y, biome_y),z=z})
local bname = minetest.get_biome_name(bdata.biome)
if bname == "Deep Forest" and pr:next(1, clust_scarcity) == 1 then
data[p_pos] = c_jewel_ore
table.insert(ores_in_mapblock, {x=x,y=y,z=z})
end
end
end
end
end
-- If jewel ore was placed in the first phase, also place additional near the initial ore
for o=1, #ores_in_mapblock do
local start_ore = ores_in_mapblock[o]
for n=1, clust_num_ores do
local ore = {}
local axes = {"z","y","x"}
for a=1, #axes do
local ax = axes[a]
-- New ores are placed within a randomly positioned bounding box
-- of size clust_size^3 around the initial ore
ore[ax] = start_ore[ax] + pr:next(rnd_minmax(pr))
-- Make sure we stay within minp, maxp
if ore[ax] < minp[ax] then
ore[ax] = minp[ax]
elseif ore[ax] > maxp[ax] then
ore[ax] = maxp[ax]
end
end
local p_pos = area:index(ore.x, ore.y, ore.z)
-- The new random pos must also be a birch tree to generate a jewel ore
if data[p_pos] == c_birch then
data[p_pos] = c_jewel_ore
end
end
end
-- Only write back to map when any ore was actually placed
if #ores_in_mapblock > 0 then
vm:set_data(data)
vm:write_to_map()
end
end
end)
else
minetest.log("error", "[jewels] Decoration ID for gigatree not found!")
end