implement initial //spline, but it isn't finished yet

worldeditadditions/lib/spline.lua

@@ -0,0 +1,80 @@
+local wea_c = worldeditadditions_core
+local Vector3 = wea_c.Vector3
+
+-- ███████ ██████  ██      ██ ███    ██ ███████ 
+-- ██      ██   ██ ██      ██ ████   ██ ██      
+-- ███████ ██████  ██      ██ ██ ██  ██ █████   
+--      ██ ██      ██      ██ ██  ██ ██ ██      
+-- ███████ ██      ███████ ██ ██   ████ ███████ 
+
+--- Creates a spline that follows the given list of points.
+-- @param	pos_list		Vector3[]	The list of points that define the path the spline should follow. Minimum: 2
+-- @param	width_start		number	The width of the spline at the start.
+-- @param	width_end		number	The width of the spline at the end. If nil, then width_start is used.
+-- @param	steps			number		The number of smoothing passes to apply to the list of points.
+-- @param	target_node		Vector3		The *normalised* name of the node to use to build the square spiral with.
+-- @returns	bool,number|string			A success boolean value, followed by either the number of the nodes set or an error message string.
+function worldeditadditions.spline(pos_list, width_start, width_end, steps, target_node)
+	if #pos_list < 2 then return false, "Error: At least 2 positions are required to make a spline." end
+	if not width_end then width_end = width_start end
+	
+	---
+	-- 0: Find bounding box
+	---
+	-- We can't use wea_c.pos.get_bounds 'cause that requires a player name
+	local pos1, pos2 = pos_list[1], pos_list[2]
+	for _, pos in pairs(pos_list) do
+		pos1, pos2 = Vector3.expand_region(pos, pos1, pos2)
+	end
+	local max_width = math.max(width_start, width_end)
+	pos1 = pos1 - max_width
+	pos2 = pos2 + max_width
+	
+	
+	---
+	-- 1: Interpolate points & widths
+	---
+	local pos_list_chaikin = wea_c.chaikin(pos_list, steps)
+	
+	local widths_lerped = {}
+	for i = 1, #pos_list_chaikin do
+		table.insert(
+			widths_lerped,
+			wea_c.lerp(width_start, width_end, (1/#pos_list_chaikin)*(i-1))
+		)
+	end
+	
+	---
+	-- 2: Fetch VoxelManipulator, prepare for replacement
+	---
+	local manip, area = worldedit.manip_helpers.init(pos1, pos2)
+	local data = manip:get_data()
+	
+	local node_id = minetest.get_content_id(target_node)
+	
+	local count = 0 -- The number of nodes replaced
+	
+	---
+	-- 3: Replace nodes
+	---
+	
+	for i = 1, #pos_list_chaikin do
+		local pos_next = pos_list_chaikin[i]
+		local width_next = widths_lerped[i]
+		
+		-- For now, just plot a point at each node
+		local index_node = area:index(pos_next.x, pos_next.y, pos_next.z)
+		data[index_node] = node_id
+		
+		count = count + 1
+	end
+	
+	---
+	-- 4: Save changes and return
+	---
+	
+	-- Save the modified nodes back to disk & return
+	worldedit.manip_helpers.finish(manip, data)
+	
+	return true, count
+end

worldeditadditions_commands/commands/spline.lua

@@ -0,0 +1,91 @@
+local wea_c = worldeditadditions_core
+local Vector3 = wea_c.Vector3
+
+-- ███████ ██████  ██      ██ ███    ██ ███████ 
+-- ██      ██   ██ ██      ██ ████   ██ ██      
+-- ███████ ██████  ██      ██ ██ ██  ██ █████   
+--      ██ ██      ██      ██ ██  ██ ██ ██      
+-- ███████ ██      ███████ ██ ██   ████ ███████ 
+
+
+worldeditadditions_core.register_command("spline", {
+	params = "<replace_node> <width_start> [<width_end=width_start> [<steps=6>]]",
+	description = "Draws a spline through the defined points. NOTE: Uses the NEW worldeditadditions position system, not the existing WorldEdit one!",
+	privs = { worldedit = true },
+	require_pos = 3,
+	parse = function(params_text)
+		local parts = wea_c.split_shell(params_text)
+		
+		local replace_node
+		local width_start
+		local width_end
+		local steps = 6
+		
+		if #parts < 1 then
+			return false, "Error: The replace_node (e.g. dirt) was not specified."
+		end
+		if #parts < 2 then
+			return false, "Error: The starting width wasn't specified."
+		end
+		
+		replace_node = worldedit.normalize_nodename(parts[1])
+		if not replace_node then
+			return false, "Error: Unknown node name '"..parts[1].."."
+		end
+		
+		width_start = tonumber(parts[2])
+		if not width_start then
+			return false, "Error: width_start must be an integer greater than or  equal to 1."
+		end
+		if width_start < 1 then
+			return false, "Error: width_start must be an integer greater than 0, but you passed '"..parts[2].."'."
+		end
+		
+		if #parts >= 3 then
+			width_end = tonumber(parts[3])
+			if not width_end then
+				return false, "Error: width_end must be an integer greater than or  equal to 1."
+			end
+			if width_end < 1 then
+				return false, "Error: width_end must be an integer greater than 0, but you passed '"..parts[3].."'."
+			end
+		else
+			width_end = width_start
+		end
+		
+		if #parts >= 4 then
+			steps = tonumber(parts[4])
+			if not steps then
+				return false, "Error: steps must be an integer greater than or equal to 0."
+			end
+			if steps < 0 then
+				return false, "Error: steps must be an integer greater than or equal to 0, but you passed '"..parts[3].."'."
+			end
+		end
+		
+		return true, replace_node, width_start, width_end, steps
+	end,
+	nodes_needed = function(player_name, _replace_node, _width_start, _width_end, steps)
+		if steps > 10 then return "may result in a large number of interpolated points" end
+		-- //overlay only modifies up to 1 node per column in the selected region
+		local pos1, pos2 = wea_c.pos.get_bounds(player_name)
+		return Vector3.volume(pos1, pos2)
+	end,
+	func = function(player_name, replace_node, width_start, width_end, steps)
+		local start_time = wea_c.get_ms_time()
+		local pos_list = wea_c.pos.get_all(player_name)
+		
+		local success, nodes_replaced = worldeditadditions.spline(
+			pos_list,
+			width_start,
+			width_end,
+			replace_node
+		)
+		if not success then return success, nodes_replaced end
+		local time_taken = wea_c.format.human_time(wea_c.get_ms_time() - start_time)
+		
+		
+		minetest.log("action", player_name.." used //spline with "..#pos_list.." initial points and "..steps.." steps, replacing "..nodes_replaced.." nodes in "..time_taken)
+		return true, nodes_replaced.." nodes replaced in "..time_taken
+	end
+})

worldeditadditions_commands/init.lua

@@ -36,6 +36,7 @@ dofile(wea_cmd.modpath.."/commands/dome.lua")
 dofile(wea_cmd.modpath.."/commands/metaball.lua")
 dofile(wea_cmd.modpath.."/commands/count.lua")
 dofile(wea_cmd.modpath.."/commands/sculpt.lua")
+dofile(wea_cmd.modpath.."/commands/spline.lua")
 
 -- Meta Commands
 dofile(wea_cmd.modpath.."/commands/meta/init.lua")

worldeditadditions_core/init.lua

@@ -41,6 +41,10 @@ wea_c.bit = dofile(wea_c.modpath.."/utils/bit.lua")
 
 wea_c.terrain = dofile(wea_c.modpath.."/utils/terrain/init.lua")
 
+local chaikin = dofile(wea_c.modpath.."/utils/chaikin.lua")
+wea_c.chaikin = chaikin.chaikin
+wea_c.lerp = chaikin.linear_interpolate
+
 dofile(wea_c.modpath.."/utils/strings/init.lua")
 dofile(wea_c.modpath.."/utils/format/init.lua")
 dofile(wea_c.modpath.."/utils/parse/init.lua")
@@ -57,7 +61,6 @@ dofile(wea_c.modpath.."/utils/player.lua") -- Player info functions
 
 
 
-
 wea_c.pos = dofile(modpath.."/core/pos.lua") -- AFTER EventEmitter
 wea_c.register_command = dofile(modpath.."/core/register_command.lua")
 wea_c.fetch_command_def = dofile(modpath.."/core/fetch_command_def.lua")

worldeditadditions_core/utils/chaikin.lua

@@ -0,0 +1,43 @@
+local wea_c = worldeditadditions_core
+
+--- Interpolates between the 2 given points
+-- @param	a		Vector3|number		The starting point.
+-- @param	b		Vector3|number		The ending point.
+-- @param	time	number				The percentage between 0 and 1 to interpolate to.
+-- @returns	Vector3|number				The interpolated point.
+local function linear_interpolate(a, b, time)
+	return ((b - a) * time) + a
+end
+
+--- Chaikin curve smoothing implementation.
+-- This algorithm works by taking a list of points that define a segmented line,
+-- and then interpolating between them to smooth the line.
+-- @source Ported from https://git.starbeamrainbowlabs.com/sbrl-GitLab/Chaikin-Generator/src/branch/master/ChaikinGenerator/ChaikinCurve.cs
+-- @param	arr_pos		Vector3[]	A list of points to interpolate.
+-- @param	steps		number		The number of interpolatioon passes to do.
+-- @returns	Vector3[]	A (longer) list of interpolated points.
+local function chaikin(arr_pos, steps)
+	
+	local result = wea_c.table.shallowcopy(arr_pos)
+	for pass = 1, steps do
+		local pos_start = result[1]
+		local pos_end = result[#result]
+				
+		for i = 1,#result-1,2 do
+			result[i] = linear_interpolate(result[i], result[i+1], 0.25)
+			table.insert(result, i+1, linear_interpolate(result[i], result[i+2]))
+		end
+		-- table.remove(result, #result-1) -- In the original, but I don't know why
+		
+		-- Keep the starting & ending positions the same
+		result[1] = pos_start
+		result[#result] = pos_end
+	end
+	
+	return result
+end
+
+return {
+	chaikin = chaikin,
+	linear_interpolate = linear_interpolate
+}