Implement slope constraint for //layers, but it isn't tested yet

CHANGELOG.md

@@ -9,6 +9,7 @@ Note to self: See the bottom of this file for the release template text.
  - Add `//airapply` for applying commands only to air nodes in the defined region
  - Use [luacheck](https://github.com/mpeterv/luacheck) to find and fix a large number of bugs and other issues
  - Multiple commands: Allow using quotes (`"thing"`, `'thing'`) to quote values when splitting
+ - Add optional slope constraint to `//layers` (inspired by [WorldPainter](https://worldpainter.net/))
 
 
 ## v1.12: The selection tools update (26th June 2021)

worldeditadditions/lib/layers.lua

@@ -1,8 +1,21 @@
---- Overlap command. Places a specified node on top of each column.
--- @module worldeditadditions.layers
+-- ██       █████  ██    ██ ███████ ██████  ███████
+-- ██      ██   ██  ██  ██  ██      ██   ██ ██
+-- ██      ███████   ████   █████   ██████  ███████
+-- ██      ██   ██    ██    ██      ██   ██      ██
+-- ███████ ██   ██    ██    ███████ ██   ██ ███████
 
-function worldeditadditions.layers(pos1, pos2, node_weights)
-	pos1, pos2 = worldedit.sort_pos(pos1, pos2)
+local wea = worldeditadditions
+
+--- Replaces the non-air nodes in each column with a list of nodes from top to bottom.
+-- @param	pos1			Vector		Position 1 of the region to operate on
+-- @param	pos2			Vector		Position 2 of the region to operate on
+-- @param	node_weights	string[]	
+-- @param	min_slope		number?		
+-- @param	max_slope		number?		
+function worldeditadditions.layers(pos1, pos2, node_weights, min_slope, max_slope)
+	pos1, pos2 = wea.vector3.sort(pos1, pos2)
+	if not min_slope then min_slope = math.rad(0) end
+	if not max_slope then max_slope = math.rad(180) end
 	-- pos2 will always have the highest co-ordinates now
 	
 	-- Fetch the nodes in the specified area
@@ -11,38 +24,53 @@ function worldeditadditions.layers(pos1, pos2, node_weights)
 	
 	local node_id_ignore = minetest.get_content_id("ignore")
 	
-	local node_ids, node_ids_count = worldeditadditions.unwind_node_list(node_weights)
+	local node_ids, node_ids_count = wea.unwind_node_list(node_weights)
 	
-	-- minetest.log("action", "pos1: " .. worldeditadditions.vector.tostring(pos1))
-	-- minetest.log("action", "pos2: " .. worldeditadditions.vector.tostring(pos2))
+	local heightmap, heightmap_size = wea.make_heightmap(
+		pos1, pos2,
+		manip, area, data
+	)
+	local slopemap = wea.calculate_slopes(heightmap, heightmap_size)
+	--luacheck:ignore 311
+	heightmap = nil -- Just in case Lua wants to garbage collect it
+	
+	-- minetest.log("action", "pos1: " .. wea.vector.tostring(pos1))
+	-- minetest.log("action", "pos2: " .. wea.vector.tostring(pos2))
 	-- for i,v in ipairs(node_ids) do
 	-- 	print("[layer] i", i, "node id", v)
 	-- end
 	-- z y x is the preferred loop order, but that isn't really possible here
 	
-	local changes = { replaced = 0, skipped_columns = 0 }
+	local changes = { replaced = 0, skipped_columns = 0, skipped_columns_slope = 0 }
 	for z = pos2.z, pos1.z, -1 do
 		for x = pos2.x, pos1.x, -1 do
 			local next_index = 1 -- We use table.insert() in make_weighted
 			local placed_node = false
 			
-			for y = pos2.y, pos1.y, -1 do
-				local i = area:index(x, y, z)
+			local hi = z*heightmap_size.x + x
 			
-				local is_air = worldeditadditions.is_airlike(data[i])
-				local is_ignore = data[i] == node_id_ignore
+			-- Again, Lua 5.1 doesn't have a continue statement :-/
+			if slopemap[hi] >= min_slope and slopemap[hi] <= max_slope then
+				for y = pos2.y, pos1.y, -1 do
+					local i = area:index(x, y, z)
 					
-				if not is_air and not is_ignore then
-					-- It's not an airlike node or something else odd
-					data[i] = node_ids[next_index]
-					next_index = next_index + 1
-					changes.replaced = changes.replaced + 1
+					local is_air = wea.is_airlike(data[i])
+					local is_ignore = data[i] == node_id_ignore
 					
-					-- If we're done replacing nodes in this column, move to the next one
-					if next_index > #node_ids then
-						break
+					if not is_air and not is_ignore then
+						-- It's not an airlike node or something else odd
+						data[i] = node_ids[next_index]
+						next_index = next_index + 1
+						changes.replaced = changes.replaced + 1
+						
+						-- If we're done replacing nodes in this column, move to the next one
+						if next_index > #node_ids then
+							break
+						end
 					end
 				end
+			else
+				changes.skipped_columns_slope = changes.skipped_columns_slope + 1
 			end
 			
 			if not placed_node then

worldeditadditions/utils/terrain.lua

@@ -91,7 +91,7 @@ end
 -- @param	heightmap		table	A ZERO indexed flat heightmap. See worldeditadditions.make_heightmap().
 -- @param	heightmap_size	int[]	The size of the heightmap in the form [ z, x ]
 -- @return	Vector[]		The calculated slope map, in the same form as the input heightmap. Each element of the array is a (floating-point) number representing the slope in that cell in radians.
-function worldeditadditions.calculate_slope(heightmap, heightmap_size)
+function worldeditadditions.calculate_slopes(heightmap, heightmap_size)
 	local normals = worldeditadditions.calculate_normals(heightmap, heightmap_size)
 	local slopes = {  }
 	

worldeditadditions/utils/vector3.lua

@@ -256,7 +256,8 @@ end
 --- Sorts the components of the given vectors.
 -- pos1 will contain the minimum values, and pos2 the maximum values.
 -- Returns 2 new vectors.
--- Note that the vectors provided do not *have* to be instances of Vector3.
+-- Note that for this specific function
+-- the vectors provided do not *have* to be instances of Vector3.
 -- It is only required that they have the keys x, y, and z.
 -- Vector3 instances are always returned.
 -- This enables convenient ingesting of positions from outside.

worldeditadditions_commands/commands/layers.lua

@@ -1,11 +1,34 @@
+local function parse_slope_range(text)
+	if string.match(text, "%.%.") then
+		-- It's in the form a..b
+		local parts = worldeditadditions.split(text, "..", true)
+		if not parts then return nil end
+		if #parts ~= 2 then return false, "Error: Exactly 2 numbers may be separated by a double dot '..' (e.g. 10..45)" end
+		local min_slope = tonumber(parts[1])
+		local max_slope = tonumber(parts[2])
+		if not min_slope then return false, "Error: Failed to parse the specified min_slope '"..tostring(min_slope).."' value as a number." end
+		if not max_slope then return false, "Error: Failed to parse the specified max_slope '"..tostring(max_slope).."' value as a number." end
+		
+		-- math.rad converts degrees to radians
+		return true, math.rad(min_slope), math.rad(max_slope)
+	else
+		-- It's a single value
+		local max_slope = tonumber(text)
+		if not max_slope then return nil end
+		
+		return true, 0, math.rad(max_slope)
+	end
+end
+
+
 --  ██████  ██    ██ ███████ ██████  ██       █████  ██    ██
 -- ██    ██ ██    ██ ██      ██   ██ ██      ██   ██  ██  ██
 -- ██    ██ ██    ██ █████   ██████  ██      ███████   ████
 -- ██    ██  ██  ██  ██      ██   ██ ██      ██   ██    ██
 --  ██████    ████   ███████ ██   ██ ███████ ██   ██    ██
 worldedit.register_command("layers", {
-	params = "[<node_name_1> [<layer_count_1>]] [<node_name_2> [<layer_count_2>]] ...",
-	description = "Replaces the topmost non-airlike nodes with layers of the given nodes from top to bottom. Like WorldEdit for MC's //naturalize command. Default: dirt_with_grass dirt 3",
+	params = "[<max_slope|min_slope..max_slope>] [<node_name_1> [<layer_count_1>]] [<node_name_2> [<layer_count_2>]] ...",
+	description = "Replaces the topmost non-airlike nodes with layers of the given nodes from top to bottom. Like WorldEdit for MC's //naturalize command. Optionally takes a maximum or minimum and maximum slope value. If a column's slope value falls outside the defined range, then it's skipped. Default: dirt_with_grass dirt 3",
 	privs = { worldedit = true },
 	require_pos = 2,
 	parse = function(params_text)
@@ -13,21 +36,40 @@ worldedit.register_command("layers", {
 			params_text = "dirt_with_grass dirt 3"
 		end
 		
-		local success, node_list = worldeditadditions.parse.weighted_nodes(
-			worldeditadditions.split_shell(params_text),
+		local parts = worldeditadditions.split_shell(params_text)
+		local success, min_slope, max_slope
+		
+		if #parts > 0 then
+			success, min_slope, max_slope = parse_slope_range(parts[1])
+			if success then
+				table.remove(parts, 1) -- Automatically shifts other values down
+			end
+		end
+		
+		if not min_slope then min_slope = 0		end
+		if not max_slope then max_slope = 180	end
+		
+		
+		local node_list
+		success, node_list = worldeditadditions.parse.weighted_nodes(
+			parts,
 			true
 		)
-		return success, node_list
+		return success, node_list, min_slope, max_slope
 	end,
 	nodes_needed = function(name)
 		return worldedit.volume(worldedit.pos1[name], worldedit.pos2[name])
 	end,
-	func = function(name, node_list)
+	func = function(name, node_list, min_slope, max_slope)
 		local start_time = worldeditadditions.get_ms_time()
-		local changes = worldeditadditions.layers(worldedit.pos1[name], worldedit.pos2[name], node_list)
+		local changes = worldeditadditions.layers(
+			worldedit.pos1[name], worldedit.pos2[name],
+			node_list,
+			min_slope, max_slope
+		)
 		local time_taken = worldeditadditions.get_ms_time() - start_time
 		
-		minetest.log("action", name .. " used //layers at " .. worldeditadditions.vector.tostring(worldedit.pos1[name]) .. ", replacing " .. changes.replaced .. " nodes and skipping " .. changes.skipped_columns .. " columns in " .. time_taken .. "s")
-		return true, changes.replaced .. " nodes replaced and " .. changes.skipped_columns .. " columns skipped in " .. worldeditadditions.format.human_time(time_taken)
+		minetest.log("action", name .. " used //layers at " .. worldeditadditions.vector.tostring(worldedit.pos1[name]) .. ", replacing " .. changes.replaced .. " nodes and skipping " .. changes.skipped_columns .. " columns ("..changes.skipped_columns_slope.." due to slope constraints) in " .. time_taken .. "s")
+		return true, changes.replaced .. " nodes replaced and " .. changes.skipped_columns .. " columns skipped ("..changes.skipped_columns_slope.." due to slope constraints) in " .. worldeditadditions.format.human_time(time_taken)
 	end
 })