many worldgen mods and gonna try technic now

mods/dfcaverns/mapgen_helper/voxelarea_iterator.lua

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+-- These functions are a minor modification of the voxel area iterator defined in the built in voxelarea.lua lua code.
+-- As such, this file is separately licened under the LGPL as follows:
+
+-- License of Minetest source code
+-------------------------------
+
+--Minetest
+--Copyright (C) 2010-2018 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+--This program is free software; you can redistribute it and/or modify
+--it under the terms of the GNU Lesser General Public License as published by
+--the Free Software Foundation; either version 2.1 of the License, or
+--(at your option) any later version.
+
+--This program is distributed in the hope that it will be useful,
+--but WITHOUT ANY WARRANTY; without even the implied warranty of
+--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--GNU Lesser General Public License for more details.
+
+--You should have received a copy of the GNU Lesser General Public License along
+--with this program; if not, write to the Free Software Foundation, Inc.,
+--51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+function VoxelArea:iter_xyz(minx, miny, minz, maxx, maxy, maxz)
+	local i = self:index(minx, miny, minz) - 1
+	
+	local x = minx - 1 -- subtracting one because x gets incremented before it gets returned the first time.
+	local xrange = maxx - minx + 1
+	local nextaction = i + 1 + xrange
+
+	local y = 0
+	local yrange = maxy - miny + 1
+	local yreqstride = self.ystride - xrange
+
+	local z = 0
+	local zrange = maxz - minz + 1
+	local multistride = self.zstride - ((yrange - 1) * self.ystride + xrange)
+
+	return function()
+		-- continue i until it needs to jump
+		i = i + 1
+		x = x + 1
+		if i ~= nextaction then
+			return i, x, y+miny, z+minz
+		end
+
+		-- continue y until maxy is exceeded
+		y = y + 1
+		x = minx -- new line
+		if y ~= yrange then
+			-- set i to index(minx, miny + y, minz + z) - 1
+			i = i + yreqstride
+			nextaction = i + xrange
+			return i, x, y+miny, z+minz
+		end
+
+		-- continue z until maxz is exceeded
+		z = z + 1
+		if z == zrange then
+			-- cuboid finished, return nil
+			return
+		end
+
+		-- set i to index(minx, miny, minz + z) - 1
+		i = i + multistride
+
+		y = 0
+		nextaction = i + xrange
+		return i, x, y+miny, z+minz
+	end
+end
+
+function VoxelArea:iterp_xyz(minp, maxp)
+	return self:iter_xyz(minp.x, minp.y, minp.z, maxp.x, maxp.y, maxp.z)
+end