From 2a90a1d235182c7dd81e094c3f03ed983f0ce39c Mon Sep 17 00:00:00 2001
From: HybridDog <ovvv@web.de>
Date: Wed, 12 Feb 2020 19:35:51 +0100
Subject: [PATCH] Add a hollowcuboid iteration helper

---
 worldedit/common.lua     | 69 ++++++++++++++++++++++++++++++++++++++++
 worldedit/primitives.lua | 32 ++++++++-----------
 2 files changed, 82 insertions(+), 19 deletions(-)

diff --git a/worldedit/common.lua b/worldedit/common.lua
index 71b43eb..2617985 100644
--- a/worldedit/common.lua
+++ b/worldedit/common.lua
@@ -122,3 +122,72 @@ function mh.finish(manip, data)
 	manip:update_map()
 end
 
+
+-- returns an iterator that returns voxelarea indices for a hollow cuboid
+function mh.iter_hollowcuboid(area, minx, miny, minz, maxx, maxy, maxz)
+	local i = area:index(minx, miny, minz) - 1
+	local xrange = maxx - minx + 1
+	local nextaction = i + 1 + xrange
+	local do_hole = false
+
+	local y = 0
+	local ydiff = maxy - miny
+	local ystride = area.ystride
+	local ymultistride = ydiff * ystride
+
+	local z = 0
+	local zdiff = maxz - minz
+	local zstride = area.zstride
+	local zcorner = true
+
+	return function()
+		-- continue i until it needs to jump ystride
+		i = i + 1
+		if i ~= nextaction then
+			return i
+		end
+
+		-- add the x offset if y (and z) are not 0 or maxy (or maxz)
+		if do_hole then
+			do_hole = false
+			i = i + xrange - 2
+			nextaction = i + 1
+			return i
+		end
+
+		-- continue y until maxy is exceeded
+		y = y+1
+		if y ~= ydiff + 1 then
+			i = i + ystride - xrange
+			if zcorner
+			or y == ydiff then
+				nextaction = i + xrange
+			else
+				nextaction = i + 1
+				do_hole = true
+			end
+			return i
+		end
+
+		-- continue z until maxz is exceeded
+		z = z+1
+		if z == zdiff + 1 then
+			-- hollowcuboid finished, return nil
+			return
+		end
+
+		-- set i to index(minx, miny, minz + z) - 1
+		i = i + zstride - (ymultistride + xrange)
+		zcorner = z == zdiff
+
+		-- y is 0, so traverse the xs
+		y = 0
+		nextaction = i + xrange
+		return i
+	end
+end
+
+function mh.iterp_hollowcuboid(area, minp, maxp)
+	return mh.iter_hollowcuboid(area, minp.x, minp.y, minp.z,
+		maxp.x, maxp.y, maxp.z)
+end
diff --git a/worldedit/primitives.lua b/worldedit/primitives.lua
index fee1682..4c86c3f 100644
--- a/worldedit/primitives.lua
+++ b/worldedit/primitives.lua
@@ -14,31 +14,25 @@ local mh = worldedit.manip_helpers
 -- @return The number of nodes added.
 function worldedit.cube(pos, width, height, length, node_name, hollow)
 	-- Set up voxel manipulator
-	local basepos = vector.subtract(pos, {x=math.floor(width/2), y=0, z=math.floor(length/2)})
-	local manip, area = mh.init(basepos, vector.add(basepos, {x=width, y=height, z=length}))
+	local basepos = vector.subtract(pos,
+		{x = math.floor(width / 2), y = 0, z = math.floor(length / 2)})
+	local endpos = vector.add(basepos, {x=width, y=height, z=length})
+	local manip, area = mh.init(basepos, endpos)
 	local data = mh.get_empty_data(area)
 
 	-- Add cube
 	local node_id = minetest.get_content_id(node_name)
-	local stride = vector.new(1, area.ystride, area.zstride)
-	local offset = vector.subtract(basepos, area.MinEdge)
 	local count = 0
+	local iterfunc
+	if hollow then
+		iterfunc = mh.iterp_hollowcuboid(area, basepos, endpos)
+	else
+		iterfunc = area:iter(basepos, endpos)
+	end
 
-	for z = 0, length-1 do
-		local index_z = (offset.z + z) * stride.z + 1 -- +1 for 1-based indexing
-		for y = 0, height-1 do
-			local index_y = index_z + (offset.y + y) * stride.y
-			for x = 0, width-1 do
-				local is_wall = z == 0 or z == length-1
-					or y == 0 or y == height-1
-					or x == 0 or x == width-1
-				if not hollow or is_wall then
-					local i = index_y + (offset.x + x)
-					data[i] = node_id
-					count = count + 1
-				end
-			end
-		end
+	for vi in iterfunc do
+		data[vi] = node_id
+		count = count+1
 	end
 
 	mh.finish(manip, data)