Merge branch 'master' of yunohost.local:mtcontrib/vector_extras into nalc-1.2-dev

http://www.adammil.net/blog/v126_A_More_Efficient_Flood_Fill.html

LICENSE.txt

@@ -1 +1 @@
-WTFPL
+CC0, except for code copied from e.g. minetest's builtin

adammil_flood_fill.lua

@@ -0,0 +1,116 @@
+-- http://www.adammil.net/blog/v126_A_More_Efficient_Flood_Fill.html
+
+local can_go
+local marked_places
+local function calc_2d_index(x, y)
+	return (y + 32768) * 65536 + x + 32768
+end
+local function mark(x, y)
+	marked_places[calc_2d_index(x, y)] = true
+end
+
+local _fill
+local function fill(x, y)
+	if can_go(x, y) then
+		_fill(x, y)
+	end
+end
+
+local corefill
+function _fill(x, y)
+	while true do
+		local ox = x
+		local oy = y
+		while can_go(x, y-1) do
+			y = y-1
+		end
+		while can_go(x-1, y) do
+			x = x-1
+		end
+		if x == ox
+		and y == oy then
+			break
+		end
+	end
+	corefill(x, y)
+end
+
+function corefill(x, y)
+	local lastcnt = 0
+	repeat
+		local cnt = 0
+		local sx = x
+		if lastcnt ~= 0
+		and not can_go(y, x) then
+			-- go right to find the x start
+			repeat
+				lastcnt = lastcnt-1
+				if lastcnt == 0 then
+					return
+				end
+				x = x+1
+			until can_go(x, y)
+			sx = x
+		else
+			-- go left if possible, and mark and _fill above
+			while can_go(x-1, y) do
+				x = x-1
+				mark(x, y)
+				if can_go(x, y-1) then
+					_fill(x, y-1)
+				end
+				cnt = cnt+1
+				lastcnt = lastcnt+1
+			end
+		end
+
+		-- go right if possible, and mark
+		while can_go(sx, y) do
+			mark(sx, y)
+			cnt = cnt+1
+			sx = sx+1
+		end
+
+		if cnt < lastcnt then
+			local e = x + lastcnt
+			sx = sx+1
+			while sx < e do
+				if can_go(sx, y) then
+					corefill(sx, y)
+				end
+				sx = sx+1
+			end
+		elseif cnt > lastcnt then
+			local ux = x + lastcnt + 1
+			while ux < sx do
+				if can_go(ux, y-1) then
+					_fill(ux, y-1)
+				end
+				ux = ux+1
+			end
+		end
+		lastcnt = cnt
+		y = y+1
+	until lastcnt == 0
+end
+
+local function apply_fill(go_test, x0, y0, allow_revisit)
+	if allow_revisit then
+		can_go = go_test
+	else
+		local visited = {}
+		can_go = function(x, y)
+			local vi = calc_2d_index(x, y)
+			if visited[vi] then
+				return false
+			end
+			visited[vi] = true
+			return go_test(x, y)
+		end
+	end
+	marked_places = {}
+	fill(x0, y0)
+	return marked_places
+end
+
+return apply_fill

fill_3d.lua

@@ -0,0 +1,53 @@
+-- Algorithm created by sofar and changed by others:
+-- https://github.com/minetest/minetest/commit/d7908ee49480caaab63d05c8a53d93103579d7a9
+
+local function search(go, p, apply_move, moves)
+	local num_moves = #moves
+
+	-- We make a stack, and manually maintain size for performance.
+	-- Stored in the stack, we will maintain tables with pos, and
+	-- last neighbor visited. This way, when we get back to each
+	-- node, we know which directions we have already walked, and
+	-- which direction is the next to walk.
+	local s = {}
+	local n = 0
+	-- The neighbor order we will visit from our table.
+	local v = 1
+
+	while true do
+		-- Push current pos onto the stack.
+		n = n + 1
+		s[n] = {p = p, v = v}
+		-- Select next node from neighbor list.
+		p = apply_move(p, moves[v])
+		-- Now we check out the node. If it is in need of an update,
+		-- it will let us know in the return value (true = updated).
+		if not go(p) then
+			-- If we don't need to "recurse" (walk) to it then pop
+			-- our previous pos off the stack and continue from there,
+			-- with the v value we were at when we last were at that
+			-- node
+			repeat
+				local pop = s[n]
+				p = pop.p
+				v = pop.v
+				s[n] = nil
+				n = n - 1
+				-- If there's nothing left on the stack, and no
+				-- more sides to walk to, we're done and can exit
+				if n == 0 and v == num_moves then
+					return
+				end
+			until v < num_moves
+			-- The next round walk the next neighbor in list.
+			v = v + 1
+		else
+			-- If we did need to walk the neighbor, then
+			-- start walking it from the walk order start (1),
+			-- and not the order we just pushed up the stack.
+			v = 1
+		end
+	end
+end
+
+return search

init.lua

@@ -1,4 +1,4 @@
-local load_time_start = minetest.get_us_time()
+local path = minetest.get_modpath"vector_extras"
 
 local funcs = {}
 
@@ -399,6 +399,66 @@ function funcs.from_number(i)
 	return {x=i, y=i, z=i}
 end
 
+local adammil_fill = dofile(path .. "/adammil_flood_fill.lua")
+function funcs.search_2d(go_test, x0, y0, allow_revisit, give_map)
+	marked_places = adammil_fill(go_test, x0, y0, allow_revisit)
+	if give_map then
+		return marked_places
+	end
+	local l = {}
+	for vi in pairs(marked_places) do
+		local x = (vi % 65536) - 32768
+		local y = (math.floor(x / 65536) % 65536) - 32768
+		l[#l+1] = {x, y}
+	end
+	return l
+end
+
+local fallings_search = dofile(path .. "/fill_3d.lua")
+local moves_touch = {
+	{x = -1, y = 0, z = 0},
+	{x = 0, y = 0, z = 0},
+	{x = 1, y = 0, z = 0},
+	{x = 0, y = -1, z = 0},
+	{x = 0, y = 1, z = 0},
+	{x = 0, y = 0, z = -1},
+	{x = 0, y = 0, z = 1},
+}
+local moves_near = {}
+for z = -1,1 do
+	for y = -1,1 do
+		for x = -1,1 do
+			moves_near[#moves_near+1] = {x = x, y = y, z = z}
+		end
+	end
+end
+
+function funcs.search_3d(can_go, startpos, apply_move, moves)
+	local visited = {}
+	local found = {}
+	local function on_visit(pos)
+		local vi = minetest.hash_node_position(pos)
+		if visited[vi] then
+			return false
+		end
+		visited[vi] = true
+		local valid_pos = can_go(pos)
+		if valid_pos then
+			found[#found+1] = pos
+		end
+		return valid_pos
+	end
+	if apply_move == "touch" then
+		apply_move = vector.add
+		moves = moves_touch
+	elseif apply_move == "near" then
+		apply_move = vector.add
+		moves = moves_near
+	end
+	fallings_search(on_visit, startpos, apply_move, moves)
+end
+
+
 local explosion_tables = {}
 function funcs.explosion_table(r)
 	local table = explosion_tables[r]
@@ -961,7 +1021,6 @@ end
 
 vector_extras_functions = funcs
 
-local path = minetest.get_modpath"vector_extras"
 dofile(path .. "/legacy.lua")
 --dofile(minetest.get_modpath("vector_extras").."/vector_meta.lua")
 
@@ -977,7 +1036,6 @@ for name,func in pairs(funcs) do
 	end
 end
 
-
 local time = (minetest.get_us_time() - load_time_start) / 1000000
 local msg = "[vector_extras] loaded after ca. " .. time .. " seconds."
 if time > 0.01 then