From 660023553b48cae4f91bd749b1dc62156adb8486 Mon Sep 17 00:00:00 2001
From: Duane Robertson <duane@duanerobertson.com>
Date: Thu, 26 May 2016 07:07:14 -0500
Subject: [PATCH] Initial fortress work (mazes).

---
 fortress.lua  | 125 ++++++++++++++++++++++++++++++++++++++++++++
 init.lua      |   2 +
 mapgen.lua    | 140 ++++++++++++++++++++++++++------------------------
 unionfind.lua |  48 +++++++++++++++++
 4 files changed, 248 insertions(+), 67 deletions(-)
 create mode 100644 fortress.lua
 create mode 100644 unionfind.lua

diff --git a/fortress.lua b/fortress.lua
new file mode 100644
index 0000000..4d5efa0
--- /dev/null
+++ b/fortress.lua
@@ -0,0 +1,125 @@
+
+fun_caves.fortress = function(node, data, area, minp, maxp, level)
+	for z = minp.z, maxp.z do
+		for x = minp.x, maxp.x do
+			ivm = area:index(x, minp.y, z)
+			for y = minp.y, maxp.y do
+				if x == minp.x or x == maxp.x or z == minp.z or z == maxp.z then
+					data[ivm] = node('default:steelblock')
+				elseif (y - minp.y) % 5 == 0 then
+					data[ivm] = node('default:steelblock')
+				else
+					data[ivm] = node('air')
+				end
+				ivm = ivm + area.ystride
+			end
+		end
+	end
+
+	local n = 16
+	local walls = {}
+
+	for y2 = 0, n-1 do
+		for i = 1, 2 * n * n do
+			walls[i] = i
+		end
+		table.shuffle(walls)
+
+		local set = unionfind(n * n)
+		local a, b, c, i, j, u, v
+
+		for m = 1, #walls do
+			c = walls[m] - 1
+			a = math.floor(c / 2)
+			i = a % n
+			j = math.floor(a / n)
+			u = c % 2 == 0 and 1 or 0
+			v = c % 2 == 1 and 1 or 0
+			b = a + u + n * v
+			if i < n - u and j < n - v and set:find(a+1) ~= set:find(b+1) then
+				set:union(a+1, b+1)
+				x = (i + u) * 5 + minp.x
+				y = minp.y + y2 * 5
+				z = (j + v) * 5 + minp.z
+				if y > minp.y and math.random(20) == 1 then
+					for z1 = z + 1, z + 4 do
+						ivm = area:index(x+1, y, z1)
+						for x1 = x + 1, x + 4 do
+							data[ivm] = node("air")
+							ivm = ivm + 1
+						end
+					end
+				end
+
+				for z1 = z, z + (1-v) * 5 do
+					for y1 = y + 1, y + 4 do
+						ivm = area:index(x, y1, z1)
+						for x1 = x, x + (1-u) * 5 do
+							data[ivm] = node("default:sandstone")
+							ivm = ivm + 1
+						end
+					end
+				end
+			end
+		end
+	end
+
+	--local n = 16
+	--local walls = {}
+	--for i = 1, 3 * n * n * n do
+	--	walls[i] = i
+	--end
+	--table.shuffle(walls)
+
+	--local set = unionfind(n * n * n)
+	--local a, b, c, i, j, k, u, v, w
+
+	--for m = 1, #walls do
+	--	c = walls[m] - 1
+	--	a = math.floor(c / 3)
+	--	i = a % n
+	--	j = math.floor(a / n) % n
+	--	k = math.floor(math.floor(a / n) / n)
+	--	u = c % 3 == 0 and 1 or 0
+	--	v = c % 3 == 1 and 1 or 0
+	--	w = c % 3 == 2 and 1 or 0
+	--	b = a + u + n * (v + n * w)
+	--	if i < n - u and j < n - v and k < n - w and set:find(a+1) ~= set:find(b+1) then
+	--		set:union(a+1, b+1)
+	--		x = (i + u) * 5 + minp.x
+	--		y = (j + v) * 5 + minp.y
+	--		z = (k + w) * 5 + minp.z
+	--		for z1 = z, z + (1-w) * 5 do
+	--			for y1 = y, y + (1-v) * 5 do
+	--				ivm = area:index(x, y1, z1)
+	--				for x1 = x, x + (1-u) * 5 do
+	--					data[ivm] = node("default:steelblock")
+	--					ivm = ivm + 1
+	--				end
+	--			end
+	--		end
+	--	end
+	--end
+
+	--local index = 0
+	--local index3d = 0
+	--for z = minp.z, maxp.z do
+	--	for x = minp.x, maxp.x do
+	--		index = index + 1
+	--		--index3d = noise_area:index(x - minp.x, 0, z - minp.z)
+	--		ivm = area:index(x, minp.y, z)
+	--		for y = minp.y, maxp.y do
+	--			if x == minp.x or x == maxp.x or z == minp.z or z == maxp.z or y == minp.y or y == maxp.y then
+	--				data[ivm] = node("default:steelblock")
+	--			elseif (y - minp.y) % 5 == 0 then
+	--				data[ivm] = node("default:stone")
+	--			else
+	--				data[ivm] = node("air")
+	--			end
+
+	--			ivm = ivm + area.ystride
+	--			--index3d = index3d + csize.x
+	--		end
+	--	end
+	--end
+end
diff --git a/init.lua b/init.lua
index 49111b6..6abea99 100644
--- a/init.lua
+++ b/init.lua
@@ -49,8 +49,10 @@ function fun_caves.clone_node(name)
 end
 
 
+dofile(path .. "/unionfind.lua")
 dofile(path .. "/nodes.lua")
 dofile(path .. "/deco.lua")
 dofile(path .. "/fungal_tree.lua")
+dofile(path .. "/fortress.lua")
 dofile(path .. "/mapgen.lua")
 dofile(path .. "/mobs.lua")
diff --git a/mapgen.lua b/mapgen.lua
index 184c39c..3c7d177 100644
--- a/mapgen.lua
+++ b/mapgen.lua
@@ -120,89 +120,95 @@ local function generate(p_minp, p_maxp, seed)
 	-- use the same seed (based on perlin noise).
 	math.randomseed(minetest.get_perlin(seed_noise):get2d({x=minp.x, y=minp.z}))
 
-	local cave_1 = minetest.get_perlin_map(cave_noise_1, csize):get3dMap_flat(minp)
-	local cave_2 = minetest.get_perlin_map(cave_noise_2, csize):get3dMap_flat(minp)
-	local cave_3 = minetest.get_perlin_map(cave_noise_3, {x=csize.x, y=csize.z}):get2dMap_flat({x=minp.x, y=minp.z})
-	local biome_n = minetest.get_perlin_map(biome_noise, csize):get3dMap_flat(minp)
+	local fortress = maxp.y / 3100
+	if maxp.y < -250 and (DEBUG or math.random(200) == 1) then
+		fun_caves.fortress(node, data, area, minp, maxp, math.ceil(maxp.y / 3100))
+		write = true
+	else
+		local cave_1 = minetest.get_perlin_map(cave_noise_1, csize):get3dMap_flat(minp)
+		local cave_2 = minetest.get_perlin_map(cave_noise_2, csize):get3dMap_flat(minp)
+		local cave_3 = minetest.get_perlin_map(cave_noise_3, {x=csize.x, y=csize.z}):get2dMap_flat({x=minp.x, y=minp.z})
+		local biome_n = minetest.get_perlin_map(biome_noise, csize):get3dMap_flat(minp)
 
-	local ivm, ivm2, height, new_node
+		local ivm, ivm2, height, new_node
 
-	local index = 0
-	local index3d = 0
-	for z = minp.z, maxp.z do
-		for x = minp.x, maxp.x do
-			index = index + 1
-			index3d = noise_area:index(x - minp.x, 0, z - minp.z)
-			ivm = area:index(x, minp.y, z)
+		local index = 0
+		local index3d = 0
+		for z = minp.z, maxp.z do
+			for x = minp.x, maxp.x do
+				index = index + 1
+				index3d = noise_area:index(x - minp.x, 0, z - minp.z)
+				ivm = area:index(x, minp.y, z)
 
-			height = heightmap[index]
-			if height >= maxp.y - 1 and data[area:index(x, maxp.y, z)] ~= node('air') then
-				height = 31000
-				heightmap[index] = height
-			elseif height <= minp.y then
-				height = -31000
-				heightmap[index] = height
-			end
+				height = heightmap[index]
+				if height >= maxp.y - 1 and data[area:index(x, maxp.y, z)] ~= node('air') then
+					height = 31000
+					heightmap[index] = height
+				elseif height <= minp.y then
+					height = -31000
+					heightmap[index] = height
+				end
 
-			for y = minp.y, maxp.y do
-				if data[ivm] ~= node('air') and y < height - cave_3[index] and cave_1[index3d] * cave_2[index3d] > 0.05 then
-					data[ivm] = node("air")
-					write = true
+				for y = minp.y, maxp.y do
+					if data[ivm] ~= node('air') and y < height - cave_3[index] and cave_1[index3d] * cave_2[index3d] > 0.05 then
+						data[ivm] = node("air")
+						write = true
 
-					if y > 0 and cave_3[index] < 1 and y == height then
-						-- Clear the air above a cave mouth.
-						ivm2 = ivm
-						for y2 = y + 1, maxp.y + 8 do
-							ivm2 = ivm2 + area.ystride
-							if data[ivm2] ~= node("default:water_source") then
-								data[ivm2] = node("air")
+						if y > 0 and cave_3[index] < 1 and y == height then
+							-- Clear the air above a cave mouth.
+							ivm2 = ivm
+							for y2 = y + 1, maxp.y + 8 do
+								ivm2 = ivm2 + area.ystride
+								if data[ivm2] ~= node("default:water_source") then
+									data[ivm2] = node("air")
+								end
 							end
 						end
 					end
-				end
 
-				ivm = ivm + area.ystride
-				index3d = index3d + csize.x
+					ivm = ivm + area.ystride
+					index3d = index3d + csize.x
+				end
 			end
 		end
-	end
 
-	-- Air needs to be placed prior to decorations.
-	local index = 0
-	local index3d = 0
-	local pn, biome
-	for z = minp.z, maxp.z do
-		for x = minp.x, maxp.x do
-			index = index + 1
-			index3d = noise_area:index(x - minp.x, 0, z - minp.z)
-			ivm = area:index(x, minp.y, z)
+		-- Air needs to be placed prior to decorations.
+		local index = 0
+		local index3d = 0
+		local pn, biome
+		for z = minp.z, maxp.z do
+			for x = minp.x, maxp.x do
+				index = index + 1
+				index3d = noise_area:index(x - minp.x, 0, z - minp.z)
+				ivm = area:index(x, minp.y, z)
 
-			height = heightmap[index]
+				height = heightmap[index]
 
-			for y = minp.y, maxp.y do
-				if y <= height - deco_depth and (height < 31000 or y < 0) then
-					new_node = fun_caves.decorate_cave(node, data, area, minp, y, ivm, biome_n[index3d])
-					if new_node then
-						data[ivm] = new_node
-						write = true
-					end
-				elseif y < height then
-					if data[ivm] == node("air") and (data[ivm - area.ystride] == node('default:stone') or data[ivm - area.ystride] == node('default:sandstone')) then
-						data[ivm - area.ystride] = node("dirt")
-						write = true
-					end
-				else
-					pn = minetest.get_perlin(plant_noise):get2d({x=x, y=z})
-					biome = biome_ids[biomemap[index]]
-					new_node = fun_caves.decorate_water(node, data, area, minp, maxp, {x=x,y=y,z=z}, ivm, biome, pn)
-					if new_node then
-						data[ivm] = new_node
-						write = true
+				for y = minp.y, maxp.y do
+					if y <= height - deco_depth and (height < 31000 or y < 0) then
+						new_node = fun_caves.decorate_cave(node, data, area, minp, y, ivm, biome_n[index3d])
+						if new_node then
+							data[ivm] = new_node
+							write = true
+						end
+					elseif y < height then
+						if data[ivm] == node("air") and (data[ivm - area.ystride] == node('default:stone') or data[ivm - area.ystride] == node('default:sandstone')) then
+							data[ivm - area.ystride] = node("dirt")
+							write = true
+						end
+					else
+						pn = minetest.get_perlin(plant_noise):get2d({x=x, y=z})
+						biome = biome_ids[biomemap[index]]
+						new_node = fun_caves.decorate_water(node, data, area, minp, maxp, {x=x,y=y,z=z}, ivm, biome, pn)
+						if new_node then
+							data[ivm] = new_node
+							write = true
+						end
 					end
+
+					ivm = ivm + area.ystride
+					index3d = index3d + csize.x
 				end
-
-				ivm = ivm + area.ystride
-				index3d = index3d + csize.x
 			end
 		end
 	end
diff --git a/unionfind.lua b/unionfind.lua
new file mode 100644
index 0000000..ada55bc
--- /dev/null
+++ b/unionfind.lua
@@ -0,0 +1,48 @@
+function table.shuffle(self)
+	local j
+	local t = self
+
+	for i = #t, 2, -1 do
+		j = math.random(i)
+		t[i], t[j] = t[j], t[i]
+	end
+end
+
+
+function unionfind(max)
+	local u = { _parent = {}, _rank = {} }
+
+	for i = 1, max do
+		u._parent[i] = i
+		u._rank[i] = 1
+	end
+
+	u.find = function(self, i)
+		local p = self._parent[i]
+		if i == p then
+			return i
+		end
+		self._parent[i] = self:find(p)
+		return self._parent[i]
+	end
+
+	u.union = function(self, i, j)
+		local root1 = self:find(i)
+		local root2 = self:find(j)
+
+		if root1 == root2 then
+			return
+		end
+
+		if self._rank[root1] > self._rank[root2] then
+			self._parent[root2] = root1
+		elseif self._rank[root2] > self._rank[root1] then
+			self._parent[root1] = root2
+		else
+			self._parent[root2] = root1
+			self._rank[root1] = self._rank[root1] + 1
+		end
+	end
+
+	return u
+end