aboutsummaryrefslogtreecommitdiff
path: root/assets
diff options
context:
space:
mode:
authororwell96 <mono96.mml@gmail.com>2017-01-17 21:54:50 +0100
committerorwell96 <mono96.mml@gmail.com>2017-01-17 21:54:50 +0100
commitb6e2aeea71394431889e9b554f190dda4adb0305 (patch)
tree498b67dfaa5987143f64bfd9fe63403843758267 /assets
parent9c400f7d435b4b1c303f1dd5ac31a8a52b263355 (diff)
Add animation for steam engine
I needed to completely rewrite the animation because irrlicht couldn't handle the animation NathanS created.
Diffstat (limited to 'assets')
-rw-r--r--assets/blender/engine-with-animation_newtry.blendbin0 -> 638904 bytes
-rw-r--r--assets/blender/engine-with-animation_newtry.blend1bin0 -> 615608 bytes
2 files changed, 0 insertions, 0 deletions
diff --git a/assets/blender/engine-with-animation_newtry.blend b/assets/blender/engine-with-animation_newtry.blend
new file mode 100644
index 0000000..101dc71
--- /dev/null
+++ b/assets/blender/engine-with-animation_newtry.blend
Binary files differ
diff --git a/assets/blender/engine-with-animation_newtry.blend1 b/assets/blender/engine-with-animation_newtry.blend1
new file mode 100644
index 0000000..77d82d4
--- /dev/null
+++ b/assets/blender/engine-with-animation_newtry.blend1
Binary files differ
id='n140' href='#n140'>140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631
--advtrains by orwell96, see readme.txt

local dir_trans_tbl={
	[0]={x=0, z=1, y=0},
	[1]={x=1, z=2, y=0},
	[2]={x=1, z=1, y=0},
	[3]={x=2, z=1, y=0},
	[4]={x=1, z=0, y=0},
	[5]={x=2, z=-1, y=0},
	[6]={x=1, z=-1, y=0},
	[7]={x=1, z=-2, y=0},
	[8]={x=0, z=-1, y=0},
	[9]={x=-1, z=-2, y=0},
	[10]={x=-1, z=-1, y=0},
	[11]={x=-2, z=-1, y=0},
	[12]={x=-1, z=0, y=0},
	[13]={x=-2, z=1, y=0},
	[14]={x=-1, z=1, y=0},
	[15]={x=-1, z=2, y=0},
}

local dir_angle_tbl={}
for d,v in pairs(dir_trans_tbl) do
	local uvec = vector.normalize(v)
	dir_angle_tbl[d] = math.atan2(-uvec.x, uvec.z)
end


function advtrains.dir_to_angle(dir)
	return dir_angle_tbl[dir] or error("advtrains: in helpers.lua/dir_to_angle() given dir="..(dir or "nil"))
end

function advtrains.dirCoordSet(coord, dir)
	return vector.add(coord, advtrains.dirToCoord(dir))
end
advtrains.pos_add_dir = advtrains.dirCoordSet

function advtrains.pos_add_angle(pos, ang)
	-- 0 is +Z -> meaning of sin/cos swapped
	return vector.add(pos, {x = -math.sin(ang), y = 0, z = math.cos(ang)})
end

function advtrains.dirToCoord(dir)
	return dir_trans_tbl[dir] or error("advtrains: in helpers.lua/dir_to_vector() given dir="..(dir or "nil"))
end
advtrains.dir_to_vector = advtrains.dirToCoord

function advtrains.maxN(list, expectstart)
	local n=expectstart or 0
	while list[n] do
		n=n+1
	end
	return n-1
end

function advtrains.minN(list, expectstart)
	local n=expectstart or 0
	while list[n] do
		n=n-1
	end
	return n+1
end

function atround(number)
	return math.floor(number+0.5)
end
atfloor = math.floor


function advtrains.round_vector_floor_y(vec)
	return {x=math.floor(vec.x+0.5), y=math.floor(vec.y), z=math.floor(vec.z+0.5)}
end

function advtrains.yawToDirection(yaw, conn1, conn2)
	if not conn1 or not conn2 then
		error("given nil to yawToDirection: conn1="..(conn1 or "nil").." conn2="..(conn1 or "nil"))
	end
	local yaw1 = advtrains.dir_to_angle(conn1)
	local yaw2 = advtrains.dir_to_angle(conn2)
	local adiff1 = advtrains.minAngleDiffRad(yaw, yaw1)
	local adiff2 = advtrains.minAngleDiffRad(yaw, yaw2)
	
	if math.abs(adiff2)<math.abs(adiff1) then
		return conn2
	else
		return conn1
	end
end

function advtrains.yawToAnyDir(yaw)
	local min_conn, min_diff=0, 10
	for conn, vec in pairs(advtrains.dir_trans_tbl) do
		local yaw1 = advtrains.dir_to_angle(conn)
		local diff = math.abs(advtrains.minAngleDiffRad(yaw, yaw1))
		if diff < min_diff then
			min_conn = conn
			min_diff = diff
		end
	end
	return min_conn
end
function advtrains.yawToClosestConn(yaw, conns)
	local min_connid, min_diff=1, 10
	for connid, conn in ipairs(conns) do
		local yaw1 = advtrains.dir_to_angle(conn.c)
		local diff = math.abs(advtrains.minAngleDiffRad(yaw, yaw1))
		if diff < min_diff then
			min_connid = connid
			min_diff = diff
		end
	end
	return min_connid
end

local pi, pi2 = math.pi, 2*math.pi
function advtrains.minAngleDiffRad(r1, r2)
	while r1>pi2 do
		r1=r1-pi2
	end
	while r1<0 do
		r1=r1+pi2
	end
	while r2>pi2 do
		r2=r2-pi2
	end
	while r1<0 do
		r2=r2+pi2
	end
	local try1=r2-r1
	local try2=r2+pi2-r1
	local try3=r2-pi2-r1
	
	local minabs = math.min(math.abs(try1), math.abs(try2), math.abs(try3))
	if minabs==math.abs(try1) then
		return try1
	end
	if minabs==math.abs(try2) then
		return try2
	end
	if minabs==math.abs(try3) then
		return try3
	end
end


-- Takes 2 connections (0...AT_CMAX) as argument
-- Returns the angle median of those 2 positions from the pov
-- of standing on the cdir1 side and looking towards cdir2
-- cdir1 - >NODE> - cdir2
function advtrains.conn_angle_median(cdir1, cdir2)
	local ang1 = advtrains.dir_to_angle(advtrains.oppd(cdir1))
	local ang2 = advtrains.dir_to_angle(cdir2)
	return ang1 + advtrains.minAngleDiffRad(ang1, ang2)/2
end

function advtrains.merge_tables(a, ...)
	local new={}
	for _,t in ipairs({a,...}) do
		for k,v in pairs(t) do new[k]=v end
	end
	return new
end
function advtrains.save_keys(tbl, keys)
	local new={}
	for _,key in ipairs(keys) do
		new[key] = tbl[key]
	end
	return new
end

function advtrains.get_real_index_position(path, index)
	if not path or not index then return end
	
	local first_pos=path[math.floor(index)]
	local second_pos=path[math.floor(index)+1]
	
	if not first_pos or not second_pos then return nil end
	
	local factor=index-math.floor(index)
	local actual_pos={x=first_pos.x-(first_pos.x-second_pos.x)*factor, y=first_pos.y-(first_pos.y-second_pos.y)*factor, z=first_pos.z-(first_pos.z-second_pos.z)*factor,}
	return actual_pos
end
function advtrains.pos_median(pos1, pos2)
	return {x=pos1.x-(pos1.x-pos2.x)*0.5, y=pos1.y-(pos1.y-pos2.y)*0.5, z=pos1.z-(pos1.z-pos2.z)*0.5}
end
function advtrains.abs_ceil(i)
	return math.ceil(math.abs(i))*math.sign(i)
end

function advtrains.serialize_inventory(inv)
	local ser={}
	local liszts=inv:get_lists()
	for lisztname, liszt in pairs(liszts) do
		ser[lisztname]={}
		for idx, item in ipairs(liszt) do
			local istring=item:to_string()
			if istring~="" then
				ser[lisztname][idx]=istring
			end
		end
	end
	return minetest.serialize(ser)
end
function advtrains.deserialize_inventory(sers, inv)
	local ser=minetest.deserialize(sers)
	if ser then
		inv:set_lists(ser)
		return true
	end
	return false
end

--is_protected wrapper that checks for protection_bypass privilege
function advtrains.is_protected(pos, name)
	if not name then
		error("advtrains.is_protected() called without name parameter!")
	end
	if minetest.check_player_privs(name, {protection_bypass=true}) then
		--player can bypass protection
		return false
	end
	return minetest.is_protected(pos, name)
end

function advtrains.is_creative(name)
	if not name then
		error("advtrains.is_creative() called without name parameter!")
	end
	if minetest.check_player_privs(name, {creative=true}) then
		return true
	end
	return minetest.settings:get_bool("creative_mode")
end

function advtrains.is_damage_enabled(name)
	if not name then
		error("advtrains.is_damage_enabled() called without name parameter!")
	end
	if minetest.check_player_privs(name, "train_admin") then
		return false
	end
	return minetest.settings:get_bool("enable_damage")
end

function advtrains.ms_to_kmh(speed)
	return speed * 3.6
end

-- 4 possible inputs:
-- integer: just do that modulo calculation
-- table with c set: rotate c
-- table with tables: rotate each
-- table with integers: rotate each (probably no use case)
function advtrains.rotate_conn_by(conn, rotate)
	if tonumber(conn) then
		return (conn+rotate)%AT_CMAX
	elseif conn.c then
		return { c = (conn.c+rotate)%AT_CMAX, y = conn.y}
	end
	local tmp={}
	for connid, data in ipairs(conn) do
		tmp[connid]=advtrains.rotate_conn_by(data, rotate)
	end
	return tmp
end


function advtrains.oppd(dir)
	return advtrains.rotate_conn_by(dir, AT_CMAX/2)
end
--conn_to_match like rotate_conn_by
--other_conns have to be a table of conn tables!
function advtrains.conn_matches_to(conn, other_conns)
	if tonumber(conn) then
		for connid, data in ipairs(other_conns) do
			if advtrains.oppd(conn) == data.c then return connid end
		end
		return false
	elseif conn.c then
		for connid, data in ipairs(other_conns) do
			local cmp = advtrains.oppd(conn)
			if cmp.c == data.c and (cmp.y or 0) == (data.y or 0) then return connid end
		end
		return false
	end
	local tmp={}
	for connid, data in ipairs(conn) do
		local backmatch = advtrains.conn_matches_to(data, other_conns)
		if backmatch then return backmatch, connid end --returns <connid of other rail> <connid of this rail>
	end
	return false
end

-- Going from the rail at pos (does not need to be rounded) along connection with id conn_idx, if there is a matching rail, return it and the matching connid
-- returns: <adjacent pos>, <conn index of adjacent>, <my conn index>, <railheight of adjacent>, (adjacent conns table), (adjacent connmap table)
-- parameter this_conns_p is connection table of this rail and is optional, is determined by get_rail_info_at if not provided.
function advtrains.get_adjacent_rail(this_posnr, this_conns_p, conn_idx)
	local this_pos = advtrains.round_vector_floor_y(this_posnr)
	local this_conns = this_conns_p
	local _
	if not this_conns then
		_, this_conns = advtrains.get_rail_info_at(this_pos)
	end
	if not conn_idx then
		for coni, _ in ipairs(this_conns) do
			local adj_pos, adj_conn_idx, _, nry, nco, ncm = advtrains.get_adjacent_rail(this_pos, this_conns, coni)
			if adj_pos then return adj_pos,adj_conn_idx,coni,nry, nco, ncm end
		end
		return nil
	end
	
	local conn = this_conns[conn_idx]
	local conn_y = conn.y or 0
	local adj_pos = advtrains.dirCoordSet(this_pos, conn.c);
	
	while conn_y>=1 do
		conn_y = conn_y - 1
		adj_pos.y = adj_pos.y + 1
	end
	
	local nextnode_ok, nextconns, nextrail_y, nextconnmap=advtrains.get_rail_info_at(adj_pos)
	if not nextnode_ok then
		adj_pos.y = adj_pos.y - 1
		conn_y = conn_y + 1
		nextnode_ok, nextconns, nextrail_y, nextconnmap=advtrains.get_rail_info_at(adj_pos)
		if not nextnode_ok then
			return nil
		end
	end
	local adj_connid = advtrains.conn_matches_to({c=conn.c, y=conn_y}, nextconns)
	if adj_connid then
		return adj_pos, adj_connid, conn_idx, nextrail_y, nextconns, nextconnmap
	end
	return nil
end

-- when a train enters a rail on connid 'conn', which connid will it go out?
-- Since 2.5: This mapping is contained in the conn_map table in the node definition!
-- returns: connid_out
function advtrains.get_matching_conn(conn, conn_map)
	if tonumber(conn_map) then
		error("Legacy call to get_matching_conn! Instead of nconns, conn_map needs to be provided!")
	end
	if not conn_map then
		--OK for two-conn rails, just return the other
		if conn==1 then return 2 end
		if conn==2 then return 1 end
		error("get_matching_conn: For connid >=3, conn_map must not be nil!")
	end
	local cout = conn_map[conn]
	if not cout then
		error("get_matching_conn: Connid "..conn.." not found in conn_map which is "..atdump(conn_map))
	end
	return cout
end

function advtrains.random_id(lenp)
	local idst=""
	local len = lenp or 6
	for i=1,len do
		idst=idst..(math.random(0,9))
	end
	return idst
end
-- Shorthand for pos_to_string and round_vector_floor_y
function advtrains.roundfloorpts(pos)
	return minetest.pos_to_string(advtrains.round_vector_floor_y(pos))
end

-- insert an element into a table if it does not yet exist there
-- equalfunc is a function to compare equality, defaults to ==
-- returns true if the element was inserted
function advtrains.insert_once(tab, elem, equalfunc)
	for _,e in pairs(tab) do
		if equalfunc and equalfunc(elem, e) or e==elem then return false end
	end
	tab[#tab+1] = elem
	return true
end

local hext = { [0]="0",[1]="1",[2]="2",[3]="3",[4]="4",[5]="5",[6]="6",[7]="7",[8]="8",[9]="9",[10]="A",[11]="B",[12]="C",[13]="D",[14]="E",[15]="F"}
local dect = { ["0"]=0,["1"]=1,["2"]=2,["3"]=3,["4"]=4,["5"]=5,["6"]=6,["7"]=7,["8"]=8,["9"]=9,["A"]=10,["B"]=11,["C"]=12,["D"]=13,["E"]=14,["F"]=15}

local f = atfloor

local function hex(i)
	local x=i+32768
	local c4 = x % 16
	x = f(x / 16)
	local c3 = x % 16
	x = f(x / 16)
	local c2 = x % 16
	x = f(x / 16)
	local c1 = x % 16
	return (hext[c1]) .. (hext[c2]) .. (hext[c3]) .. (hext[c4])
end

local function c(s,i) return dect[string.sub(s,i,i)] end

local function dec(s)
	return (c(s,1)*4096 + c(s,2)*256 + c(s,3)*16 + c(s,4))-32768
end
-- Takes a position vector and outputs a encoded value suitable as table index
-- This is essentially a hexadecimal representation of the position (+32768)
-- Order (YYY)YXXXXZZZZ
function advtrains.encode_pos(pos)
	return hex(pos.y) .. hex(pos.x) .. hex(pos.z)
end

-- decodes a position encoded with encode_pos
function advtrains.decode_pos(pts)
	if not pts or not #pts==6 then return nil end
	local stry = string.sub(pts, 1,4)
	local strx = string.sub(pts, 5,8)
	local strz = string.sub(pts, 9,12)
	return vector.new(dec(strx), dec(stry), dec(strz))
end

--[[ Benchmarking code
local tdt = {}
local tlt = {}
local tet = {}

for i=1,1000000 do
	tdt[i] = vector.new(math.random(-65536, 65535), math.random(-65536, 65535), math.random(-65536, 65535))
	if i%1000 == 0 then
		tlt[#tlt+1] = tdt[i]
	end
end

local t1=os.clock()
for i=1,1000000 do
	local pe = advtrains.encode_pos(tdt[i])
	local pb = advtrains.decode_pos(pe)
	tet[pe] = i
end
for i,v in ipairs(tlt) do
	local lk = tet[advtrains.encode_pos(v)]
end
atdebug("endec",os.clock()-t1,"s")

tet = {}

t1=os.clock()
for i=1,1000000 do
	local pe = minetest.pos_to_string(tdt[i])
	local pb = minetest.string_to_pos(pe)
	tet[pe] = i
end
for i,v in ipairs(tlt) do
	local lk = tet[minetest.pos_to_string(v)]
end
atdebug("pts",os.clock()-t1,"s")

--Results:
--2018-11-29 16:57:08: ACTION[Main]: [advtrains]endec 1.786451 s 
--2018-11-29 16:57:10: ACTION[Main]: [advtrains]pts 2.566377 s 
]]


-- Function to check whether a position is near (within range of) any player
function advtrains.position_in_range(pos, range)
	if not pos then
		return true
	end
	for _,p in pairs(minetest.get_connected_players()) do
		if vector.distance(p:get_pos(),pos)<=range then
			return true
		end
	end
	return false
end

local active_node_range = tonumber(minetest.settings:get("active_block_range"))*16 + 16
-- Function to check whether node at position(pos) is "loaded"/"active"
-- That is, whether it is within the active_block_range to a player
if minetest.is_block_active then -- define function differently whether minetest.is_block_active is available or not
	advtrains.is_node_loaded = minetest.is_block_active
else
	function advtrains.is_node_loaded(pos)
		if advtrains.position_in_range(pos, active_node_range) then
			return true
		end
	end
end


-- TrackIterator interface --

-- Metatable:
local trackiter_mt = {
	-- Internal State:
	-- branches: A list of {pos, connid, limit} for where to restart
	-- pos: The *next* position that the track iterator will return
	-- bconnid: The connid of the connection of the rail at pos that points backward
	-- tconns: The connections of the rail at pos
	-- limit: the current limit
	-- visited: a key-boolean table of already visited rails
	
	-- get whether there are still unprocessed branches
	has_next_branch = function(self)
		return #self.branches > 0
	end,
	-- go to the next unprocessed branch
	-- returns track_pos, track_connid of the switch/crossing node where the track branches off
	next_branch = function(self)
		local br = table.remove(self.branches, 1)
		-- Advance internal state
		local adj_pos, adj_connid, _, _, adj_conns, adj_connmap = advtrains.get_adjacent_rail(br.pos, nil, br.connid)
		self.pos = adj_pos
		self.bconnid = adj_connid
		self.tconns = adj_conns
		self.tconnmap = adj_connmap
		self.limit = br.limit - 1
		self.visited[advtrains.encode_pos(br.pos)] = true
		self.last_track_already_visited = false
		return br.pos, br.connid
	end,
	-- get the next track along the current branch,
	-- potentially adding branching tracks to the unprocessed branches list
	-- returns track_pos, track_connid, track_backwards_connid
	-- On error, returns nil, reason; reason is one of "track_end", "limit_hit", "already_visited"
	next_track = function(self)
		if self.last_track_already_visited then
			-- see comment below
			return nil, "already_visited"
		end
		local pos = self.pos
		if not pos then
			-- last run found track end. Return false
			return false, "track_end"
		end
		-- if limit hit, return nil to signal this
		if self.limit <= 0 then
			return nil, "limit_hit"
		end
		-- select next conn (main conn to follow is the associated connection)
		local old_bconnid = self.bconnid
		local mconnid = advtrains.get_matching_conn(self.bconnid, self.tconnmap)
		if self.visited[advtrains.encode_pos(pos)] then
			-- node was already seen
			-- Due to special requirements for the track section updater, return this first already visited track once
			-- but do not process any further rails on this branch
			-- The next call will then throw already_visited error
			self.last_track_already_visited = true
			return pos, mconnid, old_bconnid
		end
		-- If there are more connections, add these to branches
		for nconnid,_ in ipairs(self.tconns) do
			if nconnid~=mconnid and nconnid~=self.bconnid then
				table.insert(self.branches, {pos = self.pos, connid = nconnid, limit=self.limit})
			end
		end
		-- Advance internal state
		local adj_pos, adj_connid, _, _, adj_conns, adj_connmap = advtrains.get_adjacent_rail(pos, self.tconns, mconnid)
		self.pos = adj_pos
		self.bconnid = adj_connid
		self.tconns = adj_conns
		self.tconnmap = adj_connmap
		self.limit = self.limit - 1
		self.visited[advtrains.encode_pos(pos)] = true
		self.last_track_already_visited = false
		return pos, mconnid, old_bconnid
	end,

	add_branch = function(self, pos, connid)
		table.insert(self.branches, {pos = pos, connid = connid, limit=self.limit})
	end,

	is_visited = function(self, pos)
		return self.visited[advtrains.encode_pos(pos)]
	end,
}

-- Returns a new TrackIterator object

-- Parameters:
-- initial_pos: the initial track position of the track iterator
-- initial_connid: the connection index in which to traverse. If nil, adds a "branch" for every connection of the track (traverse in all directions)
-- limit: maximum distance from the start point after which the traverser stops
-- follow_all: NOT IMPLEMENTED (supposed: if true, follows all branches at multi-connection tracks, even the ones pointing backwards or the crossing track on crossings. If false, follows only switches in driving direction.)

-- Functions of the returned TrackIterator can be called via the Lua : notation, such as ti:next_track()
-- If only the main track needs to be followed, use only the ti:next_track() function and do not call ti:next_branch().
function advtrains.get_track_iterator(initial_pos, initial_connid, limit, follow_all)
	local ti = {
		visited = {}
	}
	if initial_connid then
		ti.branches = { {pos = initial_pos, connid = initial_connid, limit=limit} }
	else
		-- get track info here
		local node_ok, conns, rail_y=advtrains.get_rail_info_at(initial_pos)
		assert(node_ok, "get_track_iterator called with non-track node!")
		ti.branches = {}
		for coni, _ in pairs(conns) do
			table.insert(ti.branches, {pos = initial_pos, connid = coni, limit=limit})
		end
	end
	ti.limit = limit -- safeguard if someone adds a branch before calling anything
	setmetatable(ti, {__index=trackiter_mt})
	return ti
end

--[[
Example TrackIterator usage structure:

local ti, pos, connid, ok
ti = advtrains.get_track_iterator(initial_pos, initial_connid, 500, true)
while ti:has_next_branch() do
	pos, connid = ti:next_branch() -- in first iteration, this will be the node at initial_pos. In subsequent iterations this will be the switch node from which we are branching off
	repeat
		<do something with the track>
		if <track satisfies an abort condition> then break end --for example, when traversing should stop at TCBs this can check if there is a tcb here
		pos, connid = ti:next_track()
	until not pos -- this stops the loop when either the track end is reached or the limit is hit
	-- while loop continues with the next branch ( diverging branch of one of the switches/crossings) until no more are left
end

Example for walking only a single track (without branching):

local ti, pos, connid, ok
ti = advtrains.get_track_iterator(initial_pos, initial_connid, 500, true)

pos, connid = ti:next_branch() -- this always needs to be done at least one time, and gets the track at initial_pos
repeat
	<do something with the track>
	if <track satisfies an abort condition> then break end --for example, when traversing should stop at TCBs this can check if there is a tcb here
	ok, pos, connid = ti:next_track()
until not ok -- this stops the loop when either the track end is reached or the limit is hit
]]