mods/CORE/mcl_mapgen/init.lua

@@ -30,6 +30,7 @@ mcl_mapgen.LAST_BLOCK         = mcl_mapgen.CS - 1
 mcl_mapgen.LAST_NODE_IN_BLOCK = mcl_mapgen.BS - 1
 mcl_mapgen.LAST_NODE_IN_CHUNK = mcl_mapgen.CS_NODES - 1
 mcl_mapgen.HALF_CS_NODES      = math_floor(mcl_mapgen.CS_NODES / 2)
+mcl_mapgen.HALF_BS            = math_floor(mcl_mapgen.BS / 2)
 mcl_mapgen.CS_3D              = mcl_mapgen.CS^3
 mcl_mapgen.CHUNK_WITH_SHELL   = mcl_mapgen.CS + 2
 mcl_mapgen.CHUNK_WITH_SHELL_3D = mcl_mapgen.CHUNK_WITH_SHELL^3

mods/ITEMS/mcl_amethyst/geode.lua

@@ -0,0 +1,50 @@
+local radius_min = 3
+local radius_max = mcl_mapgen.HALF_BS
+local layers = {
+	{
+		[100] = "mcl_core:andesite",
+	},
+	{
+		[100] = "mcl_amethyst:calcite",
+	},
+	{
+		[95] = "mcl_amethyst:amethyst_block",
+		[5] = "mcl_amethyst:budding_amethyst_block",
+	},
+	{
+		[100] = "air",
+	}
+}
+
+local function place(pos, rotation, pr)
+	local radius = pr:next(radius_min, radius_max)
+	local pos = vector.add(pos, radius)
+	for x = pos.x - radius, pos.x + radius do
+		for y = pos.y - radius, pos.y + radius do
+			for z = pos.z - radius, pos.z + radius do
+				local node_pos = vector.new(x, y, z)
+				local inverted_layer = vector.round(vector.distance(node_pos, pos))
+				if inverted_layer <= radius then
+					local layer = math.max(radius - inverted_layer + 1, #layers)
+					local node_candidates = layers[layer]
+					local node_name
+					local chance_index = pr:next(1, 100)
+					local current_weight = 0
+					for chance, node_name_iterated in pairs(node_candidates) do
+						if chance_index < current_weight + chance then
+							node_name = node_name_iterated
+							break
+						end
+						current_weight = current_weight + chance
+					end
+					minetest.swap_node(node_pos, {name = node_name})
+				end
+			end
+		end
+	end
+end
+
+mcl_structures.register_structure({
+	name = "amethyst_geode",
+	place_function = place,
+})

mods/ITEMS/mcl_amethyst/init.lua

@@ -1,4 +1,6 @@
 local S = minetest.get_translator(minetest.get_current_modname())
+local modname = minetest.get_current_modname()
+local modpath = minetest.get_modpath(modname)
 mcl_amethyst = {}
 
 -- Amethyst block
@@ -208,5 +210,5 @@ if minetest.get_modpath("mcl_spyglass") then
 	end
 end
 
--- Amethyst Growing
-dofile(minetest.get_modpath(minetest.get_current_modname()) .. "/grow.lua")
+dofile(modpath .. "/grow.lua")
+dofile(modpath .. "/geode.lua")

mods/ITEMS/mcl_amethyst/mod.conf

@@ -1,5 +1,5 @@
 name = mcl_amethyst
 author = Emojiminetest
 description = Amethyst related stuff for MCL5
-depends = mcl_init, mcl_core, mcl_wip
+depends = mcl_init, mcl_core, mcl_wip, mcl_mapgen, mcl_structures
 optional_depends = mcl_spyglass, mcl_copper