MineClone2/mods/MAPGEN/mcl_structures/geode.lua

local adjacents = {
	vector.new(1, 0, 0),
	vector.new(-1, 0, 0),
	vector.new(0, 0, 1),
	vector.new(0, 0, -1),
	vector.new(0, 1, 0),
	vector.new(0, -1, 0)
}

---@param pos Vector
---@param node node
local function set_node_no_bedrock(pos, node)
	if minetest.get_node(pos).name == "mcl_core:bedrock" then return end
	minetest.set_node(pos, node)
end

local function makegeode(pos, def, pr)
	local size = pr:next(5, 7)
	local p1 = vector.offset(pos, -size, -size, -size)
	local p2 = vector.offset(pos, size, size, size)
	minetest.emerge_area(p1, p2, function(blockpos, action, calls_remaining, param)
		if calls_remaining ~= 0 then return end
		local calcite = {}
		local nn = minetest.find_nodes_in_area(p1, p2, { "group:material_stone", "group:dirt", "mcl_core:gravel" })
		table.sort(nn, function(a, b)
			return vector.distance(pos, a) < vector.distance(pos, b)
		end)
		if not nn[1] then return end

		for i = 1, pr:next(1, math.max(2, #nn - math.ceil(#nn / 5))) do
			set_node_no_bedrock(nn[i], { name = "mcl_amethyst:amethyst_block" })
		end

		for k, v in pairs(minetest.find_nodes_in_area(p1, p2, { "mcl_amethyst:amethyst_block" })) do
			local all_amethyst = true
			for kk, vv in pairs(adjacents) do
				local pp = vector.add(v, vv)
				local an = minetest.get_node(pp)
				if an.name ~= "mcl_amethyst:amethyst_block" then
					if minetest.get_item_group(an.name, "material_stone") > 0 then
						set_node_no_bedrock(pp, { name = "mcl_amethyst:calcite" })
						table.insert(calcite, pp)
						if pr:next(1, 5) == 1 then
							set_node_no_bedrock(v, { name = "mcl_amethyst:budding_amethyst_block" })
						end
						all_amethyst = false
					elseif an.name ~= "mcl_amethyst:amethyst_block" and an.name ~= "air" and
						an.name ~= "mcl_amethyst:budding_amethyst_block" then
						all_amethyst = false
					end
				end
			end
			if all_amethyst then set_node_no_bedrock(v, { name = "air" }) end
		end

		for _, v in pairs(calcite) do
			for _, vv in pairs(minetest.find_nodes_in_area(vector.offset(v, -1, -1, -1), vector.offset(v, 1, 1, 1),
				{ "group:material_stone" })) do
				set_node_no_bedrock(vv, { name = "mcl_blackstone:basalt_smooth" })
			end
		end

		for k, v in pairs(minetest.find_nodes_in_area_under_air(p1, p2,
			{ "mcl_amethyst:amethyst_block", "mcl_amethyst:budding_amethyst_block" })) do
			local r = pr:next(1, 50)
			if r < 10 then
				set_node_no_bedrock(vector.offset(v, 0, 1, 0), { name = "mcl_amethyst:amethyst_cluster", param2 = 1 })
			end
		end
	end)
	return true
end

mcl_structures.register_structure("geode", {
	place_on = { "group:material_stone" },
	noise_params = {
		offset = 0,
		scale = 0.00022,
		spread = { x = 250, y = 250, z = 250 },
		seed = 7894353,
		octaves = 3,
		persist = 0.001,
		flags = "absvalue",
	},
	flags = "force_placement",
	terrain_feature = true,
	y_max = -24,
	y_min = mcl_vars.mg_overworld_min,
	y_offset = function(pr) return pr:next(-4, -2) end,
	place_func = makegeode,
})