Bugfixes part 1

There's something wrong with the new paths, next time build a path validity checker to trace the issue

9 files changed, 227 insertions, 184 deletions

diff --git a/advtrains/helpers.lua b/advtrains/helpers.lua
index 70afadd..9ad5a8e 100644
--- a/advtrains/helpers.lua
+++ b/advtrains/helpers.lua
@@ -103,8 +103,8 @@ function advtrains.yawToClosestConn(yaw, conns)
 end

 

 function advtrains.dir_to_angle(dir)

-	local uvec = vector.normalize(advtrains.dirToCoord())

-	local yaw1 = math.atan2(uvec.z, -uvec.x)

+	local uvec = vector.normalize(advtrains.dirToCoord(dir))

+	return math.atan2(uvec.z, -uvec.x)

 end

 

 

@@ -304,8 +304,8 @@ function advtrains.get_adjacent_rail(this_posnr, this_conns_p, conn_idx, drives_
 	end

 	if not conn_idx then

 		for coni, _ in ipairs(this_conns) do

-			local adj_pos, adj_conn_idx, _, nry = advtrains.get_adjacent_rail(this_pos, this_conns, coni)

-			if adj_pos then return adj_pos,adj_conn_idx,coni,nry end

+			local adj_pos, adj_conn_idx, _, nry, nco = advtrains.get_adjacent_rail(this_pos, this_conns, coni)

+			if adj_pos then return adj_pos,adj_conn_idx,coni,nry, nco end

 		end

 		return nil

 	end

@@ -330,7 +330,7 @@ function advtrains.get_adjacent_rail(this_posnr, this_conns_p, conn_idx, drives_
 	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

+		return adj_pos, adj_connid, conn_idx, nextrail_y, nextconns

 	end

 	return nil

 end

diff --git a/advtrains/init.lua b/advtrains/init.lua
index 0043c22..69b482d 100644
--- a/advtrains/init.lua
+++ b/advtrains/init.lua
@@ -1,3 +1,7 @@
+
+local lot = os.clock()
+minetest.log("action", "[advtrains] Loading...")
+
 -- Boilerplate to support localized strings if intllib mod is installed.
 if minetest.get_modpath("intllib") then
     attrans = intllib.Getter()
@@ -10,7 +14,7 @@ end
 --Constant for maximum connection value/division of the circle
 AT_CMAX = 16
 
-advtrains = {trains={}, wagon_save={}, player_to_train_mapping={}}
+advtrains = {trains={}, player_to_train_mapping={}}
 
 --pcall
 local no_action=false
@@ -34,24 +38,16 @@ end
 function advtrains.pcall(fun)
 	if no_action then return end
 	
-	local succ, return1, return2, return3, return4=xpcall(fun, function(err)
-			if advtrains.atprint_context_tid then
-				local train=advtrains.trains[advtrains.atprint_context_tid_full]
-				advtrains.dumppath(train.path)
-				atwarn("Dumping last debug outputs: ", err)
-				atprint("Train state: index",train.index,"end_index", train.end_index,"| max_iot", train.max_index_on_track, "min_iot", train.min_index_on_track, "<> pe_min", train.path_extent_min,"pe_max", train.path_extent_max)
-				if minetest.settings:get_bool("advtrains_enable_debugging") then
-					advtrains.drb_dump(advtrains.atprint_context_tid)
-				end
-			end
-			atwarn("Lua Error occured: ", err)
-			atwarn(debug.traceback())
-		end)
-	if not succ then
-		reload_saves()
-	else
-		return return1, return2, return3, return4
-	end
+	--local succ, return1, return2, return3, return4=xpcall(fun, function(err)
+	--		atwarn("Lua Error occured: ", err)
+	--		atwarn(debug.traceback())
+	--	end)
+	--if not succ then
+	--	reload_saves()
+	--else
+	--	return return1, return2, return3, return4
+	--end
+	return fun()
 end
 
 
@@ -149,6 +145,7 @@ dofile(advtrains.modpath.."/trainlogic.lua")
 dofile(advtrains.modpath.."/trainhud.lua")
 dofile(advtrains.modpath.."/trackplacer.lua")
 dofile(advtrains.modpath.."/tracks.lua")
+dofile(advtrains.modpath.."/occupation.lua")
 dofile(advtrains.modpath.."/atc.lua")
 dofile(advtrains.modpath.."/wagons.lua")
 dofile(advtrains.modpath.."/protection.lua")
@@ -282,10 +279,6 @@ advtrains.avt_save = function(remove_players_from_wagons)
 			"atc_brake_target", "atc_wait_finish", "atc_command", "atc_delay", "door_open",
 			"text_outside", "text_inside", "couple_lck_front", "couple_lck_back", "line"
 		})
-		--then invalidate
-		if train.index then
-			v.restore_add_index=train.index-math.floor(train.index+1)
-		end
 		--then save it
 		tmp_trains[id]=v
 	end
@@ -294,7 +287,7 @@ advtrains.avt_save = function(remove_players_from_wagons)
 	-- 1 - Initial new save format.
 	local save_tbl={
 		trains = tmp_trains,
-		wagon_save = advtrains.wagon_save,
+		wagon_save = advtrains.wagons,
 		ptmap = advtrains.player_to_train_mapping,
 		atc = advtrains.atc.save_data(),
 		ndb = advtrains.ndb.save_data(),
@@ -351,7 +344,7 @@ minetest.register_globalstep(function(dtime_mt)
 		if save_timer<=0 then
 			local t=os.clock()
 			--save
-			advtrains.save()
+			--advtrains.save()
 			save_timer=save_interval
 			atprintbm("saving", t)
 		end
@@ -390,7 +383,7 @@ function advtrains.save(remove_players_from_wagons)
 	end
 	atprint("[save_all]Saved advtrains save files")
 end
-minetest.register_on_shutdown(advtrains.save)
+--minetest.register_on_shutdown(advtrains.save)
 
 -- This chat command provides a solution to the problem known on the LinuxWorks server
 -- There are many players that joined a single time, got on a train and then left forever
@@ -422,3 +415,5 @@ minetest.register_chatcommand("at_reroute",
         end,
 })
 
+local tot=(os.clock()-lot)*1000
+minetest.log("action", "[advtrains] Loaded in "..tot.."ms")
diff --git a/advtrains/nodedb.lua b/advtrains/nodedb.lua
index 592e730..6695eba 100644
--- a/advtrains/nodedb.lua
+++ b/advtrains/nodedb.lua
@@ -210,7 +210,7 @@ ndb.run_lbm = function(pos, node)
 			end
 		else
 			--if not in database, take it.
-			atlog("Node Database:", pos, "was not found in the database, have you used worldedit?")
+			--atlog("Node Database:", pos, "was not found in the database, have you used worldedit?")
 			ndb.update(pos, node)
 		end
 		return false
@@ -256,7 +256,7 @@ ndb.restore_all = function()
 			end
 		end
 	end
-	local text="Restore node database: Replaced"..cnt.."nodes, removed"..dcnt.."ghost nodes."
+	local text="Restore node database: Replaced "..cnt.." nodes, removed "..dcnt.." ghost nodes."
 	atlog(text)
 	return text
 end
diff --git a/advtrains/occupation.lua b/advtrains/occupation.lua
index f6fa6fc..7af4a3d 100644
--- a/advtrains/occupation.lua
+++ b/advtrains/occupation.lua
@@ -64,7 +64,7 @@ Composition of a step:
 4. we iterate our change lists and determine what to do
 
 ]]--
-local o
+local o = {}
 
 o.restore_required = true
 
@@ -74,6 +74,8 @@ local seqnum = 0
 local occ = {}
 local occ_chg = {}
 
+local addchg, handle_chg
+
 
 local function occget(p)
 	local t = occ[p.y]
@@ -81,10 +83,11 @@ local function occget(p)
 		occ[p.y] = {}
 		t = occ[p.y]
 	end
+	local s = t
 	t = t[p.x]
 	if not t then
-		t[p.x] = {}
-		t = t[p.x]
+		s[p.x] = {}
+		t = s[p.x]
 	end
 	return t[p.z]
 end
@@ -94,15 +97,17 @@ local function occgetcreate(p)
 		occ[p.y] = {}
 		t = occ[p.y]
 	end
+	local s = t
 	t = t[p.x]
 	if not t then
-		t[p.x] = {}
-		t = t[p.x]
+		s[p.x] = {}
+		t = s[p.x]
 	end
+	s = t
 	t = t[p.z]
 	if not t then
-		t[p.z] = {}
-		t = t[p.z]
+		s[p.z] = {}
+		t = s[p.z]
 	end
 	return t
 end
@@ -119,7 +124,7 @@ end
 function o.init_occupation(train_id, pos, oid)
 	local t = occgetcreate(pos)
 	local i = 1
-	while t[i]
+	while t[i] do
 		if t[i]==train_id then
 			break
 		end
@@ -132,7 +137,7 @@ end
 function o.set_occupation(train_id, pos, oid)
 	local t = occgetcreate(pos)
 	local i = 1
-	while t[i]
+	while t[i] do
 		if t[i]==train_id then
 			break
 		end
@@ -171,7 +176,7 @@ function o.clear_occupation(train_id, pos)
 	end
 end
 
-local function addchg(pos, train_id, old, new)
+function addchg(pos, train_id, old, new)
 	occ_chg[#occ_chg + 1] = {
 		pos = pos,
 		train_id = train_id,
@@ -196,7 +201,7 @@ function o.end_step()
 	seqnum = seqnum + 1
 end
 
-local function handle_chg(t, pos, train_id, old, new)
+function handle_chg(t, pos, train_id, old, new)
 	-- Handling the actual "change" is only necessary on_train_enter (change to 1) and on_train_leave (change from 1)
 	if new==1 then
 		o.call_enter_callback(pos, train_id)
diff --git a/advtrains/path.lua b/advtrains/path.lua
index a98a1b5..039085c 100644
--- a/advtrains/path.lua
+++ b/advtrains/path.lua
@@ -113,8 +113,8 @@ function advtrains.path_create(train, pos, connid, rel_index)
 	train.path_dist = {}
 	
 	train.path_dir = {
-		[ 0] = conns[connid],
-		[-1] = conns[mconnid]
+		[1] = conns[connid].c,
+		[0] = advtrains.oppd(conns[mconnid].c)
 	}
 	
 	train.path_ext_f=0
@@ -123,31 +123,49 @@ function advtrains.path_create(train, pos, connid, rel_index)
 	train.path_trk_b=0
 	train.path_req_f=0
 	train.path_req_b=0
+	atdebug("path_create",train)
 	
 end
 
+function advtrains.path_invalidate(train)
+	train.path = nil
+	train.path_dist = nil
+	train.path_cp = nil
+	train.path_cn = nil
+	train.path_dir = nil
+	train.path_ext_f=0
+	train.path_ext_b=0
+	train.path_trk_f=0
+	train.path_trk_b=0
+	train.path_req_f=0
+	train.path_req_b=0
+end
+
 -- Function to get path entry at a position. This function will automatically calculate more of the path when required.
 -- returns: pos, on_track
 function advtrains.path_get(train, index)
+	if not train.path then
+		error("For train "..train.id..": path_get called but there's no path set yet!")
+	end
 	if index ~= atfloor(index) then
 		error("For train "..train.id..": Called path_get() but index="..index.." is not a round number")
 	end
 	while index > train.path_ext_f do
 		local pos = train.path[train.path_ext_f]
 		local connid = train.path_cn[train.path_ext_f]
-		local node_ok, this_conns, adj_pos, adj_connid, conn_idx, nextrail_y
+		local node_ok, this_conns, adj_pos, adj_connid, conn_idx, nextrail_y, next_conns
 		if train.path_ext_f == train.path_trk_f then
-			node_ok, this_conns = advtrains.get_rail_info_at(this_pos)
+			node_ok, this_conns = advtrains.get_rail_info_at(pos)
 			if not node_ok then error("For train "..train.id..": Path item "..train.path_ext_f.." on-track but not a valid node!") end
-			adj_pos, adj_connid, conn_idx, nextrail_y = advtrains.get_adjacent_rail(pos, this_conns, connid, train.drives_on)
+			adj_pos, adj_connid, conn_idx, nextrail_y, next_conns = advtrains.get_adjacent_rail(pos, this_conns, connid, train.drives_on)
 		end
 		train.path_ext_f = train.path_ext_f + 1
 		if adj_pos then
 			adj_pos.y = adj_pos.y + nextrail_y
 			train.path_cp[train.path_ext_f] = adj_connid
-			local mconnid = advtrains.get_matching_conn(adj_connid)
+			local mconnid = advtrains.get_matching_conn(adj_connid, #next_conns)
 			train.path_cn[train.path_ext_f] = mconnid
-			train.path_dir[train.path_ext_f] = this_conns[mconnid]
+			train.path_dir[train.path_ext_f+1] = this_conns[mconnid].c
 			train.path_trk_f = train.path_ext_f
 		else
 			-- off-track fallback behavior
@@ -160,19 +178,21 @@ function advtrains.path_get(train, index)
 	while index < train.path_ext_b do
 		local pos = train.path[train.path_ext_b]
 		local connid = train.path_cp[train.path_ext_b]
-		local node_ok, this_conns, adj_pos, adj_connid, conn_idx, nextrail_y
+		local node_ok, this_conns, adj_pos, adj_connid, conn_idx, nextrail_y, next_conns
 		if train.path_ext_b == train.path_trk_b then
-			node_ok, this_conns = advtrains.get_rail_info_at(this_pos)
+			node_ok, this_conns = advtrains.get_rail_info_at(pos)
 			if not node_ok then error("For train "..train.id..": Path item "..train.path_ext_f.." on-track but not a valid node!") end
-			adj_pos, adj_connid, conn_idx, nextrail_y = advtrains.get_adjacent_rail(pos, this_conns, connid, train.drives_on)
+			adj_pos, adj_connid, conn_idx, nextrail_y, next_conns = advtrains.get_adjacent_rail(pos, this_conns, connid, train.drives_on)
 		end
 		train.path_ext_b = train.path_ext_b - 1
 		if adj_pos then
 			adj_pos.y = adj_pos.y + nextrail_y
-			train.path_cp[train.path_ext_b] = adj_connid
-			local mconnid = advtrains.get_matching_conn(adj_connid)
-			train.path_cn[train.path_ext_b] = mconnid
-			train.path_dir[train.path_ext_b] = advtrains.oppd(this_conns[mconnid]) --we need to rotate this here so that it points in positive path direction
+			train.path_cn[train.path_ext_b] = adj_connid
+			local mconnid = advtrains.get_matching_conn(adj_connid, #next_conns)
+			train.path_cp[train.path_ext_b] = mconnid
+			
+			train.path_dir[train.path_ext_b] = advtrains.oppd(this_conns[mconnid].c)
+			
 			train.path_trk_b = train.path_ext_b
 		else
 			-- off-track fallback behavior
@@ -200,7 +220,7 @@ function advtrains.path_get_interpolated(train, index)
 	local i_floor = atfloor(index)
 	local i_ceil = i_floor + 1
 	local frac = index - i_floor
-	local p_floor,  = advtrains.path_get(train, i_floor)
+	local p_floor = advtrains.path_get(train, i_floor)
 	local p_ceil = advtrains.path_get(train, i_ceil)
 	-- Note: minimal code duplication to path_get_adjacent, for performance
 	
@@ -211,7 +231,7 @@ function advtrains.path_get_interpolated(train, index)
 	
 	local ang = advtrains.minAngleDiffRad(a_floor, a_ceil)
 	
-	return vector.add(p_floor, vector.multiply(vector.subtract(npos2, npos), frac), (a_floor + frac * ang)%(2*math.pi), p_floor, p_ceil -- TODO does this behave correctly?
+	return vector.add(p_floor, vector.multiply(vector.subtract(p_ceil, p_floor), frac)), (a_floor + frac * ang)%(2*math.pi), p_floor, p_ceil -- TODO does this behave correctly?
 end
 -- returns the 2 path positions directly adjacent to index and the fraction on how to interpolate between them
 -- returns: pos_floor, pos_ceil, fraction
@@ -219,26 +239,43 @@ function advtrains.path_get_adjacent(train, index)
 	local i_floor = atfloor(index)
 	local i_ceil = i_floor + 1
 	local frac = index - i_floor
-	local p_floor,  = advtrains.path_get(train, i_floor)
+	local p_floor = advtrains.path_get(train, i_floor)
 	local p_ceil = advtrains.path_get(train, i_ceil)
 	return p_floor, p_ceil, frac
 end
 
 function advtrains.path_get_index_by_offset(train, index, offset)
-	local pos_in_train_left=pit
-	local index=train.index
-	if pos_in_train_left>(index-math.floor(index))*(train.path_dist[math.floor(index)] or 1) then
-		pos_in_train_left=pos_in_train_left - (index-math.floor(index))*(train.path_dist[math.floor(index)] or 1)
-		index=math.floor(index)
-		while pos_in_train_left>(train.path_dist[index-1] or 1) do
-			pos_in_train_left=pos_in_train_left - (train.path_dist[index-1] or 1)
-			index=index-1
+	local off = offset
+	local idx = atfloor(index)
+	-- go down to floor. Calculate required path_dist
+	advtrains.path_get_adjacent(train, idx)
+	off = off + ((index-idx) * train.path_dist[idx])
+	--atdebug("pibo: 1 off=",off,"idx=",idx,"  index=",index)
+	
+	-- then walk the path back until we overshoot (off becomes >=0)
+	while off<0 do
+		idx = idx - 1
+		advtrains.path_get_adjacent(train, idx)
+		off = off + train.path_dist[idx]
+	end
+	--atdebug("pibo: 2 off=",off,"idx=",idx)
+	-- then walk the path forward until we would overshoot
+	while off - train.path_dist[idx] >= 0 do
+		idx = idx - 1
+		advtrains.path_get_adjacent(train, idx)
+		if not train.path_dist[idx] then
+			atdebug("second while",idx)
+			for i=-5,5 do
+				atdebug(idx+i,train.path_dist[idx+i])
+			end
 		end
-		index=index-(pos_in_train_left/(train.path_dist[index-1] or 1))
-	else
-		index=index-(pos_in_train_left/(train.path_dist[math.floor(index-1)] or 1))
+		off = off - train.path_dist[idx]
 	end
-	return index
+	--atdebug("pibo: 3 off=",off,"idx=",idx," returns:",idx + (off / train.path_dist[idx]))
+	-- we should now be on the floor of the index we actually want.
+	-- give them the rest!
+	
+	return idx + (off / train.path_dist[idx])
 end
 
 local PATH_CLEAR_KEEP = 2
@@ -246,14 +283,14 @@ local PATH_CLEAR_KEEP = 2
 function advtrains.path_clear_unused(train)
 	for i = train.path_ext_b, train.path_req_b - PATH_CLEAR_KEEP do
 		train.path[i] = nil
-		train.path_dist[i] = nil
+		train.path_dist[i-1] = nil
 		train.path_cp[i] = nil
 		train.path_cn[i] = nil
 		train.path_dir[i] = nil
 	end
 	for i = train.path_req_f + PATH_CLEAR_KEEP, train.path_ext_f do
 		train.path[i] = nil
-		train.path_dist[i-1] = nil
+		train.path_dist[i] = nil
 		train.path_cp[i] = nil
 		train.path_cn[i] = nil
 		train.path_dir[i+1] = nil
diff --git a/advtrains/textures/advtrains_wagon_placeholder.png b/advtrains/textures/advtrains_wagon_placeholder.png
new file mode 100644
index 0000000..383c181
--- /dev/null
+++ b/advtrains/textures/advtrains_wagon_placeholder.png
diff --git a/advtrains/trainhud.lua b/advtrains/trainhud.lua
index e48e3e4..26af2a1 100644
--- a/advtrains/trainhud.lua
+++ b/advtrains/trainhud.lua
@@ -60,7 +60,7 @@ function advtrains.on_control_change(pc, train, flip)
 				end
 				act=true
 			else
-				train.movedir = -train.movedir
+				--train.movedir = -train.movedir
 			end
 		end
 		if pc.left then
diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
index 110d3f6..12ec8b5 100644
--- a/advtrains/trainlogic.lua
+++ b/advtrains/trainlogic.lua
@@ -70,24 +70,26 @@ advtrains.mainloop_trainlogic=function(dtime)
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=sid(k)
 		advtrains.atprint_context_tid_full=k
-		train_ensure_clean(k, v, dtime)
+		advtrains.train_ensure_clean(k, v, dtime, advtrains.occ.restore_required)
 	end
 	
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=sid(k)
 		advtrains.atprint_context_tid_full=k
-		train_step_b(k, v, dtime)
+		advtrains.train_step_b(k, v, dtime)
 	end
 	
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=sid(k)
 		advtrains.atprint_context_tid_full=k
-		train_step_c(k, v, dtime)
+		advtrains.train_step_c(k, v, dtime)
 	end
 	
 	advtrains.atprint_context_tid=nil
 	advtrains.atprint_context_tid_full=nil
 	
+	advtrains.occ.end_step()
+	
 	atprintbm("trainsteps", t)
 	endstep()
 end
@@ -216,7 +218,7 @@ local function write_occupation(win, train_id, train, write_mode)
 	local c_index = math.ceil(win[1])
 	while win[n_window] do
 		local winix = win[n_window]
-		local oid = WINDOW_ZONE_IDS[n_windows - 1]
+		local oid = WINDOW_ZONE_IDS[n_window - 1]
 		while winix > c_index do
 			local pos = advtrains.path_get(train, c_index)
 			if write_mode == 1 then
@@ -242,7 +244,7 @@ end
 -- - the train's path got cleared
 -- - the occupation table got cleared
 -- Additionally, this gets called outside the step cycle to initialize and/or remove a train, then occ_write_mode is set.
-local function train_ensure_clean(id, train, dtime, report_occupations, occ_write_mode)
+function advtrains.train_ensure_clean(id, train, dtime, report_occupations, occ_write_mode)
 	train.dirty = true
 	if train.no_step then return end
 
@@ -258,29 +260,31 @@ local function train_ensure_clean(id, train, dtime, report_occupations, occ_writ
 	--restore path
 	if not train.path then
 		if not train.last_pos then
-			atwarn("Train",id": Restoring path failed, no last_pos set! Train will be disabled. You can try to fix the issue in the save file.")
+			atwarn("Train",id,": Restoring path failed, no last_pos set! Train will be disabled. You can try to fix the issue in the save file.")
 			train.no_step = true
 			return
 		end
 		if not train.last_connid then
-			atwarn("Train",id": Restoring path failed, no last_connid set! Will assume 1")
+			atwarn("Train",id,": Restoring path: no last_connid set! Will assume 1")
 		end
 		
-		local result = advtrains.path_create(train, train.last_pos, train.last_connid, train.last_frac or 0)
+		local result = advtrains.path_create(train, train.last_pos, train.last_connid or 1, train.last_frac or 0)
 		
 		if result==false then
-			atwarn("Train",id": Restoring path failed, node at",train.last_pos,"is gone! Train will be disabled. You can try to fix the issue in the save file.")
+			atwarn("Train",id,": Restoring path failed, node at",train.last_pos,"is gone! Train will be disabled. You can try to fix the issue in the save file.")
 			train.no_step = true
 			return
 		elseif result==nil then
 			if not train.wait_for_path then
-				atwarn("Train",id": Can't initialize: Waiting for the (yet unloaded) node at",train.last_pos," to be loaded.")
+				atwarn("Train",id,": Can't initialize: Waiting for the (yet unloaded) node at",train.last_pos," to be loaded.")
 			end
 			train.wait_for_path = true
 		end
 		-- by now, we should have a working initial path
+		train.wait_for_path = false
 		train.occwindows = nil
 		advtrains.update_trainpart_properties(id)
+		atdebug("Train",id,": Successfully restored path at",train.last_pos," connid",train.last_connid," frac",train.last_frac)
 		-- TODO recoverposition?!
 	end
 	
@@ -289,18 +293,18 @@ local function train_ensure_clean(id, train, dtime, report_occupations, occ_writ
 		train.occwindows = calc_occwindows(id, train)
 	end
 	if report_occupations then
-		write_occupation(train.occwindows, train, occ_write_mode)
+		write_occupation(train.occwindows, id, train, occ_write_mode)
 	end
 	
 	train.dirty = false -- TODO einbauen!
 end
 
-local function train_step_b(id, train, dtime)
+function advtrains.train_step_b(id, train, dtime)
 	if train.no_step or train.wait_for_path then return end
 	
 	-- in this code, we check variables such as path_trk_? and path_dist. We need to ensure that the path is known for the whole 'Train' zone
-	advtrains.path_get(train, train.index + 1)
-	advtrains.path_get(train, train.end_index - 1)
+	advtrains.path_get(train, atfloor(train.index + 2))
+	advtrains.path_get(train, atfloor(train.end_index - 1))
 	
 	--- 3. handle velocity influences ---
 	local train_moves=(train.velocity~=0)
@@ -318,7 +322,7 @@ local function train_step_b(id, train, dtime)
 	end
 	
 	--- 3a. this can be useful for debugs/warnings and is used for check_trainpartload ---
-	local t_info, train_pos=sid(id), advtrains.path_get(atfloor(train.index))
+	local t_info, train_pos=sid(id), advtrains.path_get(train, atfloor(train.index))
 	if train_pos then
 		t_info=t_info.." @"..minetest.pos_to_string(train_pos)
 		--atprint("train_pos:",train_pos)
@@ -416,13 +420,13 @@ local function train_step_b(id, train, dtime)
 
 end
 
-local function train_recalc_occupation()
+local function train_recalc_occupation(id, train)
 	local new_occwindows = calc_occwindows(id, train)
 	apply_occupation_changes(train.occwindows, new_occwindows, id)
 	train.occwindows = new_occwindows
 end
 
-local function train_step_c(id, train, dtime)
+function advtrains.train_step_c(id, train, dtime)
 if train.no_step or train.wait_for_path then return end
 	
 	-- all location/extent-critical actions have been done.
@@ -433,7 +437,7 @@ if train.no_step or train.wait_for_path then return end
 	
 	-- Set our path restoration position
 	local fli = atfloor(train.index)
-	train.last_pos = advtrains.path_get(fli)
+	train.last_pos = advtrains.path_get(train, fli)
 	train.last_connid = train.path_cn[fli]
 	train.last_frac = train.index - fli
 	
@@ -453,7 +457,8 @@ if train.no_step or train.wait_for_path then return end
 		
 		local collpos
 		local coll_grace=1
-		collpos=advtrains.path_get_index_by_offset(train, train.index-coll_grace)
+		local collindex = advtrains.path_get_index_by_offset(train, train.index, coll_grace)
+		collpos = advtrains.path_get(train, atround(collindex))
 		if collpos then
 			local rcollpos=advtrains.round_vector_floor_y(collpos)
 			for x=-train.extent_h,train.extent_h do
@@ -509,8 +514,8 @@ function advtrains.create_new_train_at(pos, connid, ioff, trainparts)
 	local new_id=advtrains.random_id()
 	while advtrains.trains[new_id] do new_id=advtrains.random_id() end--ensure uniqueness
 	
-	t={}
-	t.id = newtrain_id
+	local t={}
+	t.id = new_id
 	
 	t.last_pos=pos
 	t.last_connid=connid
@@ -520,22 +525,24 @@ function advtrains.create_new_train_at(pos, connid, ioff, trainparts)
 	t.velocity=0
 	t.trainparts=trainparts
 	
-	
 	advtrains.trains[new_id] = t
+	atdebug("Created new train:",t)
 	
 	advtrains.update_trainpart_properties(new_id)
 	
-	train_ensure_clean(new_id, advtrains.trains[new_id], 0, true, 1)
+	advtrains.train_ensure_clean(new_id, advtrains.trains[new_id], 0, true, 1)
 	
-	return newtrain_id
+	return new_id
 end
 
 function advtrains.remove_train(id)
 	local train = advtrains.trains[id]
 	
+	advtrains.train_ensure_clean(id, train)
+	
 	advtrains.update_trainpart_properties(id)
 	
-	train_ensure_clean(id, train, 0, true, 2)
+	advtrains.train_ensure_clean(id, train, 0, true, 2)
 	
 	local tp = train.trainparts
 	
@@ -549,7 +556,7 @@ end
 function advtrains.add_wagon_to_train(wagon_id, train_id, index)
 	local train=advtrains.trains[train_id]
 	
-	train_ensure_clean(train_id, train)
+	advtrains.train_ensure_clean(train_id, train)
 	
 	if index then
 		table.insert(train.trainparts, index, wagon_id)
@@ -578,10 +585,10 @@ function advtrains.update_trainpart_properties(train_id, invert_flipstate)
 		
 		-- 1st: update wagon data (pos_in_train a.s.o)
 		if data then
-			local wagon = minetest.registered_luaentites[data.type]
+			local wagon = advtrains.wagon_prototypes[data.type]
 			if not wagon then
 				atwarn("Wagon '",data.type,"' couldn't be found. Please check that all required modules are loaded!")
-				wagon = minetest.registered_luaentites["advtrains:wagon_placeholder"]
+				wagon = advtrains.wagon_prototypes["advtrains:wagon_placeholder"]
 			end
 			
 			rel_pos=rel_pos+wagon.wagon_span
@@ -608,6 +615,8 @@ function advtrains.update_trainpart_properties(train_id, invert_flipstate)
 			train.extent_h = math.max(train.extent_h, wagon.extent_h or 1);
 		end
 	end
+	train.trainlen = rel_pos
+	train.locomotives_in_train = count_l
 end
 
 -- This function checks whether entities need to be spawned for certain wagons, and spawns them.
@@ -624,13 +633,11 @@ function advtrains.spawn_wagons(train_id)
 				
 				if minetest.get_node_or_nil(pos) then
 					local wt = advtrains.get_wagon_prototype(data)
-					wagon=minetest.add_entity(pos, wt):get_luaentity()
+					local wagon = minetest.add_entity(pos, wt):get_luaentity()
 					wagon:set_id(w_id)
 				end
 			end
 		end
-		
-		
 	end
 end
 		
@@ -641,7 +648,7 @@ function advtrains.split_train_at_wagon(wagon_id)
 	local train=advtrains.trains[data.train_id]
 	local _, wagon = advtrains.get_wagon_prototype(data)
 	
-	train_ensure_clean(data.train_id, train)
+	advtrains.train_ensure_clean(data.train_id, train)
 	
 	local index=advtrains.path_get_index_by_offset(train, train.index, -(data.pos_in_train + wagon.wagon_span))
 	
@@ -901,21 +908,8 @@ end
 function advtrains.invalidate_path(id)
 	local v=advtrains.trains[id]
 	if not v then return end
-	--TODO duplicate code in init.lua avt_save()!
-	if v.index then
-		v.restore_add_index=v.index-math.floor(v.index+1)
-	end
-	v.path=nil
-	v.path_dist=nil
-	v.index=nil
-	v.end_index=nil
-	v.min_index_on_track=nil
-	v.max_index_on_track=nil
-	v.path_extent_min=nil
-	v.path_extent_max=nil
-
-	v.detector_old_index=nil
-	v.detector_old_end_index=nil
+	advtrains.path_invalidate(v)
+	v.dirty = true
 end
 
 --not blocking trains group
diff --git a/advtrains/wagons.lua b/advtrains/wagons.lua
index 83f919e..c3217e2 100644
--- a/advtrains/wagons.lua
+++ b/advtrains/wagons.lua
@@ -2,24 +2,27 @@
 -- Holds all logic related to wagons

 -- From now on, wagons are, just like trains, just entries in a table

 -- All data that is static is stored in the entity prototype (self).

---   A copy of the entity prototype is always available inside minetest.registered_luaentities

+--   A copy of the entity prototype is always available inside wagon_prototypes

 -- All dynamic data is stored in the (new) wagons table

 -- An entity is ONLY spawned by update_trainpart_properties when it finds it useful.

 -- Only data that are only important to the entity itself are stored in the luaentity

 

 advtrains.wagons = {}

+advtrains.wagon_prototypes = {}

+

 

 --

-function advtrains.create_wagon(type, owner)

+function advtrains.create_wagon(wtype, owner)

 	local new_id=advtrains.random_id()

 	while advtrains.wagons[new_id] do new_id=advtrains.random_id() end

 	local wgn = {}

-	wgn.type = type

+	wgn.type = wtype

 	wgn.seatp = {}

 	wgn.owner = owner

 	wgn.id = new_id

 	---wgn.train_id = train_id   --- will get this via update_trainpart_properties

 	advtrains.wagons[new_id] = wgn

+	atdebug("Created new wagon:",wgn)

 	return new_id

 end

 

@@ -59,6 +62,9 @@ function wagon:set_id(wid)
 	

 	local data = advtrains.wagons[self.id]

 	

+	data.object = self.object

+	atdebug("Created wagon entity:",self.name," w_id",wid," t_id",data.train_id)

+	

 	if self.has_inventory then

 		--to be used later

 		local inv=minetest.create_detached_inventory("advtrains_wgn_"..self.id, {

@@ -89,20 +95,27 @@ function wagon:set_id(wid)
 	if self.custom_on_activate then

 		self:custom_on_activate(dtime_s)

 	end

+end

 

 function wagon:get_staticdata()

 	return "STATIC"

 end

 

 function wagon:ensure_init()

-	if self.initialized then

-		if self.noninitticks then self.noninitticks=nil end

-		return true

+			-- Note: A wagon entity won't exist when there's no train, because the train is

+			-- the thing that actually creates the entity

+			-- Train not being set just means that this will happen as soon as the train calls update_trainpart_properties.

+	if self.initialized and self.id then

+		local data = advtrains.wagons[self.id]

+		if data.train_id then

+			if self.noninitticks then self.noninitticks=nil end

+			return true

+		end

 	end

 	if not self.noninitticks then self.noninitticks=0 end

 	self.noninitticks=self.noninitticks+1

 	if self.noninitticks>20 then

-		self.object:remove()

+		self:destroy()

 	else

 		self.object:setvelocity({x=0,y=0,z=0})

 	end

@@ -110,7 +123,8 @@ function wagon:ensure_init()
 end

 

 function wagon:train()

-	return advtrains.trains[self.train_id]

+	local data = advtrains.wagons[self.id]

+	return advtrains.trains[data.train_id]

 end

 

 -- Remove the wagon

@@ -158,26 +172,28 @@ function wagon:destroy()
 	-- single left-click shows warning

 	-- shift leftclick destroys

 	-- not when a driver is inside

-	local data = advtrains.wagons[self.id]

-	

-	if self.custom_on_destroy then

-		self.custom_on_destroy(self)

-	end

-	

-	for seat,_ in pairs(data.seatp) do

-		self:get_off(seat)

+	if self.id then

+		local data = advtrains.wagons[self.id]

+		

+		if self.custom_on_destroy then

+			self.custom_on_destroy(self)

+		end

+		

+		for seat,_ in pairs(data.seatp) do

+			self:get_off(seat)

+		end

+		

+		if data.train_id and self:train() then

+			table.remove(self:train().trainparts, data.pos_in_trainparts)

+			advtrains.update_trainpart_properties(self.train_id)

+			advtrains.wagons[self.id]=nil

+			if self.discouple then self.discouple.object:remove() end--will have no effect on unloaded objects

+			return true

+		end

 	end

-	

 	atprint("[wagon ", self.id, "]: destroying")

 	

 	self.object:remove()

-	

-	if self.train_id and self:train() then

-	table.remove(self:train().trainparts, data.pos_in_trainparts)

-	advtrains.update_trainpart_properties(self.train_id)

-	advtrains.wagons[self.id]=nil

-	if self.discouple then self.discouple.object:remove() end--will have no effect on unloaded objects

-	return true

 end

 

 

@@ -190,16 +206,10 @@ function wagon:on_step(dtime)
 		local data = advtrains.wagons[self.id]

 		

 		if not pos then

-			atprint("["..self.unique_id.."][fatal] missing position (object:getpos() returned nil)")

+			atdebug("["..self.id.."][fatal] missing position (object:getpos() returned nil)")

 			return

 		end

 		

-		--is my train still here

-		if not self.train_id or not self:train() then

-			atprint("[wagon "..self.unique_id.."] missing train_id, destroying")

-			self:destroy()

-			return

-		end

 		if not data.seatp then

 			data.seatp={}

 		end

@@ -331,7 +341,7 @@ function wagon:on_step(dtime)
 		if data.pos_in_trainparts and data.pos_in_trainparts>1 then

 			if train.velocity==0 and not data.dcpl_lock then

 				if not self.discouple or not self.discouple.object:getyaw() then

-					atprint(self.unique_id,"trying to spawn discouple")

+					atprint(self.id,"trying to spawn discouple")

 					local yaw = self.object:getyaw()

 					local flipsign=data.wagon_flipped and -1 or 1

 					local dcpl_pos = vector.add(pos, {y=0, x=-math.sin(yaw)*self.wagon_span*flipsign, z=math.cos(yaw)*self.wagon_span*flipsign})

@@ -342,7 +352,7 @@ function wagon:on_step(dtime)
 						--box is hidden when attached, so unuseful.

 						--object:set_attach(self.object, "", {x=0, y=0, z=self.wagon_span*10}, {x=0, y=0, z=0})

 						self.discouple=le

-						atprint(self.unique_id,"success")

+						atprint(self.id,"success")

 					else

 						atprint("Couldn't spawn DisCouple")

 					end

@@ -370,7 +380,7 @@ function wagon:on_step(dtime)
 		

 		--automatic get_on

 		--needs to know index and path

-		if self.door_entry and gp.door_open and gp.door_open~=0 and gp.velocity==0 then

+		if self.door_entry and train.door_open and train.door_open~=0 and train.velocity==0 then

 			--using the mapping created by the trainlogic globalstep

 			for i, ino in ipairs(self.door_entry) do

 				--fct is the flipstate flag from door animation above

@@ -399,7 +409,7 @@ function wagon:on_step(dtime)
 		end

 		

 		--checking for environment collisions(a 3x3 cube around the center)

-		if not gp.recently_collided_with_env then

+		if not train.recently_collided_with_env then

 			local collides=false

 			local exh = self.extent_h or 1

 			local exv = self.extent_v or 2

@@ -407,9 +417,10 @@ function wagon:on_step(dtime)
 				for y=0,exv do

 					for z=-exh,exh do

 						local node=minetest.get_node_or_nil(vector.add(npos, {x=x, y=y, z=z}))

-						if (advtrains.train_collides(node)) then

-							collides=true

-						end

+						-- TODO

+						--if (advtrains.train_collides(node)) then

+						--	collides=true

+						--end

 					end

 				end

 			end

@@ -432,8 +443,8 @@ function wagon:on_step(dtime)
 		end

 		

 		--FIX: use index of the wagon, not of the train.

-		local velocity = (gp.velocity*gp.movedir)

-		local acceleration = (gp.last_accel or 0)

+		local velocity = train.velocity

+		local acceleration = (train.acceleration or 0)

 		local velocityvec = vector.multiply(vdir, velocity)

 		local accelerationvec = vector.multiply(vdir, acceleration)

 		

@@ -482,13 +493,13 @@ function wagon:on_step(dtime)
 				self:update_animation(gp.velocity, self.old_velocity)

 			end

 			if self.custom_on_velocity_change then

-				self:custom_on_velocity_change(gp.velocity, self.old_velocity or 0, dtime)

+				self:custom_on_velocity_change(train.velocity, self.old_velocity or 0, dtime)

 			end

 		end

 		

 		

 		self.old_velocity_vector=velocityvec

-		self.old_velocity = gp.velocity

+		self.old_velocity = train.velocity

 		self.old_acceleration_vector=accelerationvec

 		self.old_yaw=yaw

 		atprintbm("wagon step", t)

@@ -542,7 +553,7 @@ function wagon:on_rightclick(clicker)
 					for pos,ent in ipairs(poss) do

 						form = form .. "button_exit[0.5,"..(pos-0.5)..";4,1;"..ent.key..";"..ent.name.."]"

 					end

-					minetest.show_formspec(pname, "advtrains_seating_"..self.unique_id, form)

+					minetest.show_formspec(pname, "advtrains_seating_"..self.id, form)

 				end

 			else

 				self:get_off(no)

@@ -553,7 +564,7 @@ function wagon:on_rightclick(clicker)
 			if self.seat_groups then

 				if #self.seats==0 then

 					if self.has_inventory and self.get_inventory_formspec then

-						minetest.show_formspec(pname, "advtrains_inv_"..self.unique_id, self:get_inventory_formspec(pname))

+						minetest.show_formspec(pname, "advtrains_inv_"..self.id, self:get_inventory_formspec(pname))

 					end

 					return

 				end

@@ -687,7 +698,7 @@ function wagon:show_get_on_form(pname)
 	local data = advtrains.wagons[self.id]

 	if #self.seats==0 then

 		if self.has_inventory and self.get_inventory_formspec then

-			minetest.show_formspec(pname, "advtrains_inv_"..self.unique_id, self:get_inventory_formspec(pname))

+			minetest.show_formspec(pname, "advtrains_inv_"..self.id, self:get_inventory_formspec(pname))

 		end

 		return

 	end

@@ -705,7 +716,7 @@ function wagon:show_get_on_form(pname)
 	if self.has_inventory and self.get_inventory_formspec then

 		form=form.."button_exit[1,7;3,1;inv;"..attrans("Show Inventory").."]"

 	end

-	minetest.show_formspec(pname, "advtrains_geton_"..self.unique_id, form)

+	minetest.show_formspec(pname, "advtrains_geton_"..self.id, form)

 end

 function wagon:show_wagon_properties(pname)

 	--[[

@@ -754,9 +765,9 @@ function wagon:show_bordcom(pname)
 		linhei=5

 		local pre_own, pre_wl, owns_any = nil, nil, minetest.check_player_privs(pname, "train_admin")

 		for i, tpid in ipairs(train.trainparts) do

-			local ent = advtrains.wagon_save[tpid]

+			local ent = advtrains.wagons[tpid]

 			if ent then

-				local ename = ent.entity_name

+				local ename = ent.type

 				form = form .. "item_image["..i..","..linhei..";1,1;"..ename.."]"

 				if i~=1 then

 					if not ent.dcpl_lock then

@@ -809,7 +820,7 @@ function wagon:show_bordcom(pname)
 	end

 	form = form .. "button[0.5,8;3,1;Save;save]"

 	

-	minetest.show_formspec(pname, "advtrains_bordcom_"..self.unique_id, form)

+	minetest.show_formspec(pname, "advtrains_bordcom_"..self.id, form)

 end

 function wagon:handle_bordcom_fields(pname, formname, fields)

 	local data = advtrains.wagons[self.id]

@@ -837,8 +848,8 @@ function wagon:handle_bordcom_fields(pname, formname, fields)
 	for i, tpid in ipairs(train.trainparts) do

 		if fields["dcpl_"..i] then

 			for _,wagon in pairs(minetest.luaentities) do

-				if wagon.is_wagon and wagon.initialized and wagon.unique_id==tpid then

-					wagon:safe_decouple(pname)												-- TODO: Move this into external function (don't search entity?)

+				if wagon.is_wagon and wagon.initialized and wagon.id==tpid then

+					wagon:safe_decouple(pname)										-- TODO: Move this into external function (don't search entity?)

 				end

 			end

 		end

@@ -954,7 +965,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 		uid=string.match(formname, "^advtrains_bordcom_(.+)$")

 		if uid then

 			for _,wagon in pairs(minetest.luaentities) do

-				if wagon.is_wagon and wagon.initialized and wagon.unique_id==uid then

+				if wagon.is_wagon and wagon.initialized and wagon.id==uid then

 					wagon:handle_bordcom_fields(player:get_player_name(), formname, fields)

 				end

 			end

@@ -962,7 +973,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	end)

 end)

 function wagon:seating_from_key_helper(pname, fields, no)

-	local data = advtrains.wagons[wagon.id]

+	local data = advtrains.wagons[self.id]

 	local sgr=self.seats[no].group

 	for _,access in ipairs(self.seat_groups[sgr].access_to) do

 		if fields["sgr_"..access] and self:check_seat_group_access(pname, access) then

@@ -1000,7 +1011,7 @@ function wagon:check_seat_group_access(pname, sgr)
 	return true

 end

 function wagon:reattach_all()

-	local data = advtrains.wagons[wagon.id]

+	local data = advtrains.wagons[self.id]

 	if not data.seatp then data.seatp={} end

 	for seatno, pname in pairs(data.seatp) do

 		local p=minetest.get_player_by_name(pname)

@@ -1015,7 +1026,7 @@ function wagon:safe_decouple(pname)
 		minetest.chat_send_player(pname, "Missing train_operator privilege")

 		return false

 	end

-	local data = advtrains.wagons[wagon.id]

+	local data = advtrains.wagons[self.id]

 	if data.dcpl_lock then

 		minetest.chat_send_player(pname, "Couple is locked (ask owner or admin to unlock it)")

 		return false

@@ -1028,11 +1039,11 @@ end
 

 function advtrains.get_wagon_prototype(data)

 	local wt = data.type

-	if not minetest.registered_luaentities[wt] then

+	if not advtrains.wagon_prototypes[wt] then

 		atprint("Unable to load wagon type",wt,", using placeholder")

 		wt="advtrains:wagon_placeholder"

 	end

-	return wt, minetest.registered_luaentities[wt]

+	return wt, advtrains.wagon_prototypes[wt]

 end

 

 function advtrains.register_wagon(sysname_p, prototype, desc, inv_img, nincreative)

@@ -1042,6 +1053,7 @@ function advtrains.register_wagon(sysname_p, prototype, desc, inv_img, nincreati
 	end

 	setmetatable(prototype, {__index=wagon})

 	minetest.register_entity(":"..sysname,prototype)

+	advtrains.wagon_prototypes[sysname] = prototype

 	

 	minetest.register_craftitem(":"..sysname, {

 		description = desc,

@@ -1049,7 +1061,7 @@ function advtrains.register_wagon(sysname_p, prototype, desc, inv_img, nincreati
 		wield_image = inv_img,

 		stack_max = 1,

 		

-		groups = { not_in_creative_inventory = nincreative and 0 or 1}

+		groups = { not_in_creative_inventory = nincreative and 1 or 0},

 		

 		on_place = function(itemstack, placer, pointed_thing)

 			return advtrains.pcall(function()

@@ -1082,7 +1094,7 @@ function advtrains.register_wagon(sysname_p, prototype, desc, inv_img, nincreati
 					return

 				end

 				

-				local wid = advtrains.create_wagon(type, pname)

+				local wid = advtrains.create_wagon(sysname, pname)

 				

 				local id=advtrains.create_new_train_at(pointed_thing.under, plconnid, 0, {wid})

 				

@@ -1099,7 +1111,7 @@ end
 -- Placeholder wagon. Will be spawned whenever a mod is missing

 advtrains.register_wagon("advtrains:wagon_placeholder", {

 	visual="sprite",

-	textures = {"advtrains_wheel.png"},

+	textures = {"advtrains_wagon_placeholder.png"},

 	collisionbox = {-0.3,-0.3,-0.3, 0.3,0.3,0.3},

 	visual_size = {x=0.7, y=0.7},

 	initial_sprite_basepos = {x=0, y=0},

@@ -1112,5 +1124,5 @@ advtrains.register_wagon("advtrains:wagon_placeholder", {
 	assign_to_seat_group = {},

 	wagon_span=1,

 	drops={},

-}, "Wagon placeholder", "advtrains_subway_wagon_inv.png", true)

+}, "Wagon placeholder", "advtrains_wagon_placeholder.png", true)