Restructure mod directory

1 files changed, 0 insertions, 875 deletions

diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
deleted file mode 100644
index eb45500..0000000
--- a/advtrains/trainlogic.lua
+++ /dev/null
@@ -1,875 +0,0 @@
---trainlogic.lua
---controls train entities stuff about connecting/disconnecting/colliding trains and other things
-
-
-local benchmark=false
-local bm={}
-local bmlt=0
-local bmsteps=0
-local bmstepint=200
-printbm=function(action, ta)
-	if not benchmark then return end
-	local t=(os.clock()-ta)*1000
-	if not bm[action] then
-		bm[action]=t
-	else
-		bm[action]=bm[action]+t
-	end
-	bmlt=bmlt+t
-end
-function endstep()
-	if not benchmark then return end
-	bmsteps=bmsteps-1
-	if bmsteps<=0 then
-		bmsteps=bmstepint
-		for key, value in pairs(bm) do
-			minetest.chat_send_all(key.." "..(value/bmstepint).." ms avg.")
-		end
-		minetest.chat_send_all("Total time consumed by all advtrains actions per step: "..(bmlt/bmstepint).." ms avg.")
-		bm={}
-		bmlt=0
-	end
-end
-
-advtrains.train_accel_force=2--per second and divided by number of wagons
-advtrains.train_brake_force=3--per second, not divided by number of wagons
-advtrains.train_roll_force=0.5--per second, not divided by number of wagons, acceleration when rolling without brake
-advtrains.train_emerg_force=10--for emergency brakes(when going off track)
-
-advtrains.audit_interval=30
-
-
-advtrains.trains={}
-advtrains.wagon_save={}
-
---load initially
-advtrains.fpath=minetest.get_worldpath().."/advtrains"
-local file, err = io.open(advtrains.fpath, "r")
-if not file then
-	local er=err or "Unknown Error"
-	print("[advtrains]Failed loading advtrains save file "..er)
-else
-	local tbl = minetest.deserialize(file:read("*a"))
-	if type(tbl) == "table" then
-		advtrains.trains=tbl
-	end
-	file:close()
-end
-advtrains.fpath_ws=minetest.get_worldpath().."/advtrains_wagon_save"
-local file, err = io.open(advtrains.fpath_ws, "r")
-if not file then
-	local er=err or "Unknown Error"
-	print("[advtrains]Failed loading advtrains save file "..er)
-else
-	local tbl = minetest.deserialize(file:read("*a"))
-	if type(tbl) == "table" then
-		advtrains.wagon_save=tbl
-	end
-	file:close()
-end
-
-
-advtrains.save = function()
-	--print("[advtrains]saving")
-	advtrains.invalidate_all_paths()
-	local datastr = minetest.serialize(advtrains.trains)
-	if not datastr then
-		minetest.log("error", "[advtrains] Failed to serialize train data!")
-		return
-	end
-	local file, err = io.open(advtrains.fpath, "w")
-	if err then
-		return err
-	end
-	file:write(datastr)
-	file:close()
-	
-	-- update wagon saves
-	for _,wagon in pairs(minetest.luaentities) do
-		if wagon.is_wagon and wagon.initialized then
-			wagon:get_staticdata()
-		end
-	end
-	--cross out userdata
-	for w_id, data in pairs(advtrains.wagon_save) do
-		data.name=nil
-		data.object=nil
-		if data.driver then
-			data.driver_name=data.driver:get_player_name()
-			data.driver=nil
-		else
-			data.driver_name=nil
-		end
-		if data.discouple then
-			data.discouple.object:remove()
-			data.discouple=nil
-		end
-	end
-	--print(dump(advtrains.wagon_save))
-	datastr = minetest.serialize(advtrains.wagon_save)
-	if not datastr then
-		minetest.log("error", "[advtrains] Failed to serialize train data!")
-		return
-	end
-	file, err = io.open(advtrains.fpath_ws, "w")
-	if err then
-		return err
-	end
-	file:write(datastr)
-	file:close()
-	
-	advtrains.save_trackdb()
-	advtrains.atc.save()
-end
-minetest.register_on_shutdown(advtrains.save)
-
-advtrains.save_and_audit_timer=advtrains.audit_interval
-minetest.register_globalstep(function(dtime)
-	advtrains.save_and_audit_timer=advtrains.save_and_audit_timer-dtime
-	if advtrains.save_and_audit_timer<=0 then
-		local t=os.clock()
-		
-		--save
-		advtrains.save()
-		advtrains.save_and_audit_timer=advtrains.audit_interval
-		printbm("saving", t)
-	end
-	--regular train step
-	local t=os.clock()
-	for k,v in pairs(advtrains.trains) do
-		advtrains.train_step(k, v, dtime)
-	end
-	
-	--see tracks.lua
-	if advtrains.detector.clean_step_before then
-		advtrains.detector.finalize_restore()
-	end
-	
-	printbm("trainsteps", t)
-	endstep()
-end)
-
-function advtrains.train_step(id, train, dtime)
-	--Legacy: set drives_on and max_speed
-	if not train.drives_on or not train.max_speed then
-		advtrains.update_trainpart_properties(id)
-	end
-	--TODO check for all vars to be present
-	if not train.velocity then
-		train.velocity=0
-	end
-	if not train.movedir or (train.movedir~=1 and train.movedir~=-1) then
-		train.movedir=1
-	end
-	--very unimportant thing: check if couple is here
-	if train.couple_eid_front and (not minetest.luaentities[train.couple_eid_front] or not minetest.luaentities[train.couple_eid_front].is_couple) then train.couple_eid_front=nil end
-	if train.couple_eid_back and (not minetest.luaentities[train.couple_eid_back] or not minetest.luaentities[train.couple_eid_back].is_couple) then train.couple_eid_back=nil end
-	
-	--skip certain things (esp. collision) when not moving
-	local train_moves=(train.velocity~=0)
-	
-	--if not train.last_pos then advtrains.trains[id]=nil return end
-	
-	if not advtrains.pathpredict(id, train) then 
-		print("pathpredict failed(returned false)")
-		train.velocity=0
-		train.tarvelocity=0
-		return
-	end
-	
-	local path=advtrains.get_or_create_path(id, train)
-	if not path then
-		train.velocity=0
-		train.tarvelocity=0
-		print("train has no path for whatever reason")
-		return 
-	end
-	
-	local train_end_index=advtrains.get_train_end_index(train)
-	--apply off-track handling:
-	local front_off_track=train.max_index_on_track and train.index>train.max_index_on_track
-	local back_off_track=train.min_index_on_track and train_end_index<train.min_index_on_track
-	if front_off_track and back_off_track then--allow movement in both directions
-		if train.tarvelocity>1 then train.tarvelocity=1 end
-	elseif front_off_track then--allow movement only backward
-		if train.movedir==1 and train.tarvelocity>0 then train.tarvelocity=0 end
-		if train.movedir==-1 and train.tarvelocity>1 then train.tarvelocity=1 end
-	elseif back_off_track then--allow movement only forward
-		if train.movedir==-1 and train.tarvelocity>0 then train.tarvelocity=0 end
-		if train.movedir==1 and train.tarvelocity>1 then train.tarvelocity=1 end
-	end
-	
-	--update advtrains.detector
-	if not train.detector_old_index then
-		train.detector_old_index = math.floor(train_end_index)
-		train.detector_old_end_index = math.floor(train_end_index)
-	end
-	local ifo, ifn, ibo, ibn = train.detector_old_index, math.floor(train.index), train.detector_old_end_index, math.floor(train_end_index)
-	if ifn>ifo then
-		for i=ifo, ifn do
-			if path[i] then
-				advtrains.detector.enter_node(path[i], id)
-			end
-		end
-	elseif ifn<ifo then
-		for i=ifn, ifo do
-			if path[i] then
-				advtrains.detector.leave_node(path[i], id)
-			end
-		end
-	end
-	if ibn<ibo then
-		for i=ibn, ibn do
-			if path[i] then
-				advtrains.detector.enter_node(path[i], id)
-			end
-		end
-	elseif ibn>ibo then
-		for i=ibo, ibn do
-			if path[i] then
-				advtrains.detector.leave_node(path[i], id)
-			end
-		end
-	end
-	train.detector_old_index = math.floor(train.index)
-	train.detector_old_end_index = math.floor(train_end_index)
-	
-	--remove?
-	if #train.trainparts==0 then
-		print("[advtrains][train "..sid(id).."] has empty trainparts, removing.")
-		advtrains.detector.leave_node(path[train.detector_old_index], id)
-		advtrains.trains[id]=nil
-		return
-	end
-	
-	if train_moves then
-		--check for collisions by finding objects
-		
-		--heh, new collision again.
-		--this time, based on NODES and the advtrains.detector.on_node table.
-		local collpos
-		local coll_grace=1
-		if train.movedir==1 then
-			collpos=advtrains.get_real_index_position(path, train.index-coll_grace)
-		else
-			collpos=advtrains.get_real_index_position(path, train_end_index+coll_grace)
-		end
-		if collpos then
-			local rcollpos=advtrains.round_vector_floor_y(collpos)
-			for x=-1,1 do
-				for z=-1,1 do
-					local testpos=vector.add(rcollpos, {x=x, y=0, z=z})
-					local testpts=minetest.pos_to_string(testpos)
-					if advtrains.detector.on_node[testpts] and advtrains.detector.on_node[testpts]~=id then
-						--collides
-						advtrains.spawn_couple_on_collide(id, testpos, advtrains.detector.on_node[testpts], train.movedir==-1)
-						
-						train.recently_collided_with_env=true
-						train.velocity=0.5*train.velocity
-						train.movedir=train.movedir*-1
-						train.tarvelocity=0
-						
-					end
-				end
-			end
-		end
-	end
-	--check for any trainpart entities if they have been unloaded. do this only if train is near a player, to not spawn entities into unloaded areas
-	--todo function will be taken by update_trainpart_properties
-	train.check_trainpartload=(train.check_trainpartload or 0)-dtime
-	local node_range=(math.max((minetest.setting_get("active_block_range") or 0),1)*16)
-	if train.check_trainpartload<=0 then
-		local ori_pos=advtrains.get_real_index_position(path, train.index) --not much to calculate
-		--print("[advtrains][train "..id.."] at "..minetest.pos_to_string(vector.round(ori_pos)))
-		
-		local should_check=false
-		for _,p in ipairs(minetest.get_connected_players()) do
-			should_check=should_check or ((vector.distance(ori_pos, p:getpos())<node_range))
-		end
-		if should_check then
-			advtrains.update_trainpart_properties(id)
-		end
-		train.check_trainpartload=2
-	end
-	
-	
-	--handle collided_with_env
-	if train.recently_collided_with_env then
-		train.tarvelocity=0
-		if not train_moves then
-			train.recently_collided_with_env=false--reset status when stopped
-		end
-	end
-	if train.locomotives_in_train==0 then
-		train.tarvelocity=0
-	end
-	
-	--interpret ATC command
-	if train.atc_brake_target and train.atc_brake_target>=train.velocity then
-		train.atc_brake_target=nil
-	end
-	if train.atc_wait_finish then
-		if not train.atc_brake_target and train.velocity==train.tarvelocity then
-			train.atc_wait_finish=nil
-		end
-	end
-	if train.atc_command then
-		if train.atc_delay<=0 and not train.atc_wait_finish then
-			advtrains.atc.execute_atc_command(id, train)
-		else
-			train.atc_delay=train.atc_delay-dtime
-		end
-	end
-	
-	--make brake adjust the tarvelocity if necessary
-	if train.brake and (math.ceil(train.velocity)-1)<train.tarvelocity then
-		train.tarvelocity=math.max((math.ceil(train.velocity)-1), 0)
-	end
-	--apply tarvel(but with physics in mind!)
-	if train.velocity~=train.tarvelocity then
-		local applydiff=0
-		local mass=#train.trainparts
-		local diff=train.tarvelocity-train.velocity
-		if diff>0 then--accelerating, force will be brought on only by locomotives.
-			--print("accelerating with default force")
-			applydiff=(math.min((advtrains.train_accel_force*train.locomotives_in_train*dtime)/mass, math.abs(diff)))
-		else--decelerating
-			if front_off_track or back_off_track or train.recently_collided_with_env then --every wagon has a brake, so not divided by mass.
-				--print("braking with emergency force")
-				applydiff= -(math.min((advtrains.train_emerg_force*dtime), math.abs(diff)))
-			elseif train.brake or (train.atc_brake_target and train.atc_brake_target<train.velocity) then
-				--print("braking with default force")
-				--no math.min, because it can grow beyond tarvelocity, see up there
-				--dont worry, it will never fall below zero.
-				applydiff= -((advtrains.train_brake_force*dtime))
-			else
-				--print("roll")
-				applydiff= -(math.min((advtrains.train_roll_force*dtime), math.abs(diff)))
-			end
-		end
-		train.last_accel=(applydiff*train.movedir)
-		train.velocity=math.min(math.max( train.velocity+applydiff , 0), train.max_speed or 10)
-	else
-		train.last_accel=0
-	end
-	
-	--move
-	--TODO 3,5 + 0.7
-	train.index=train.index and train.index+(((train.velocity*train.movedir)/(train.path_dist[math.floor(train.index)] or 1))*dtime) or 0
-	
-end
-
-
---structure of train table:
---[[
-trains={
-	[train_id]={
-		trainparts={
-			[n]=wagon_id
-		}
-		path={path}
-		velocity
-		tarvelocity
-		index
-		trainlen
-		path_inv_level
-		last_pos       |
-		last_dir       | for pathpredicting.
-	}
-}
---a wagon itself has the following properties:
-wagon={
-	unique_id
-	train_id
-	pos_in_train (is index difference, including train_span stuff)
-	pos_in_trainparts (is index in trainparts tabel of trains)
-}
-inherited by metatable:
-wagon_proto={
-	wagon_span
-}
-]]
-
---returns new id
-function advtrains.create_new_train_at(pos, pos_prev)
-	local newtrain_id=os.time()..os.clock()
-	while advtrains.trains[newtrain_id] do newtrain_id=os.time()..os.clock() end--ensure uniqueness(will be unneccessary)
-	
-	advtrains.trains[newtrain_id]={}
-	advtrains.trains[newtrain_id].last_pos=pos
-	advtrains.trains[newtrain_id].last_pos_prev=pos_prev
-	advtrains.trains[newtrain_id].tarvelocity=0
-	advtrains.trains[newtrain_id].velocity=0
-	advtrains.trains[newtrain_id].trainparts={}
-	return newtrain_id
-end
-
---returns false on failure. handle this case!
-function advtrains.pathpredict(id, train)
-	
-	--print("pos ",x,y,z)
-	--::rerun::
-	if not train.index then train.index=0 end
-	if not train.path or #train.path<2 then
-		if not train.last_pos then
-			--no chance to recover
-			print("[advtrains]train hasn't saved last-pos, removing train.")
-			advtrains.train[id]=nil
-			return false
-		end
-		
-		local node_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(train.last_pos), train.drives_on)
-		
-		if node_ok==nil then
-			--block not loaded, do nothing
-			return nil
-		elseif node_ok==false then
-			print("[advtrains]no track here, (fail) removing train.")
-			advtrains.trains[id]=nil
-			return false
-		end
-		
-		if not train.last_pos_prev then
-			--no chance to recover
-			print("[advtrains]train hasn't saved last-pos_prev, removing train.")
-			advtrains.trains[id]=nil
-			return false
-		end
-		
-		local prevnode_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(train.last_pos_prev), train.drives_on)
-		
-		if prevnode_ok==nil then
-			--block not loaded, do nothing
-			return nil
-		elseif prevnode_ok==false then
-			print("[advtrains]no track at prev, (fail) removing train.")
-			advtrains.trains[id]=nil
-			return false
-		end
-		
-		train.index=(train.restore_add_index or 0)+(train.savedpos_off_track_index_offset or 0)
-		--restore_add_index is set by save() to prevent trains hopping to next round index. should be between -0.5 and 0.5
-		--savedpos_off_track_index_offset is set if train went off track. see below.
-		train.path={}
-		train.path_dist={}
-		train.path[0]=train.last_pos
-		train.path[-1]=train.last_pos_prev
-		train.path_dist[-1]=vector.distance(train.last_pos, train.last_pos_prev)
-	end
-	
-	local pregen_front=2
-	local pregen_back=2
-	if train.velocity>0 then
-		if train.movedir>0 then
-			pregen_front=2+math.ceil(train.velocity*0.15) --assumes server step of 0.1 seconds, +50% tolerance
-		else
-			pregen_back=2+math.ceil(train.velocity*0.15)
-		end
-	end
-	
-	
-	local maxn=advtrains.maxN(train.path)
-	while (maxn-train.index) < pregen_front do--pregenerate
-		--print("[advtrains]maxn conway for ",maxn,minetest.pos_to_string(path[maxn]),maxn-1,minetest.pos_to_string(path[maxn-1]))
-		local conway=advtrains.conway(train.path[maxn], train.path[maxn-1], train.drives_on)
-		if conway then
-			train.path[maxn+1]=conway
-			train.max_index_on_track=maxn
-		else
-			--do as if nothing has happened and preceed with path
-			--but do not update max_index_on_track
-			--print("over-generating path max to index "..maxn+1)
-			train.path[maxn+1]=vector.add(train.path[maxn], vector.subtract(train.path[maxn], train.path[maxn-1]))
-		end
-		train.path_dist[maxn]=vector.distance(train.path[maxn+1], train.path[maxn])
-		maxn=advtrains.maxN(train.path)
-	end
-	
-	local minn=advtrains.minN(train.path)
-	while (train.index-minn) < (train.trainlen or 0) + pregen_back do --post_generate. has to be at least trainlen. (we let go of the exact calculation here since this would be unuseful here)
-		--print("[advtrains]minn conway for ",minn,minetest.pos_to_string(path[minn]),minn+1,minetest.pos_to_string(path[minn+1]))
-		local conway=advtrains.conway(train.path[minn], train.path[minn+1], train.drives_on)
-		if conway then
-			train.path[minn-1]=conway
-			train.min_index_on_track=minn
-		else
-			--do as if nothing has happened and preceed with path
-			--but do not update min_index_on_track
-			--print("over-generating path min to index "..minn-1)
-			train.path[minn-1]=vector.add(train.path[minn], vector.subtract(train.path[minn], train.path[minn+1]))
-		end
-		train.path_dist[minn-1]=vector.distance(train.path[minn], train.path[minn-1])
-		minn=advtrains.minN(train.path)
-	end
-	if not train.min_index_on_track then train.min_index_on_track=0 end
-	if not train.max_index_on_track then train.max_index_on_track=0 end
-	
-	--make pos/yaw available for possible recover calls
-	if train.max_index_on_track<train.index then --whoops, train went too far. the saved position will be the last one that lies on a track, and savedpos_off_track_index_offset will hold how far to go from here
-		train.savedpos_off_track_index_offset=train.index-train.max_index_on_track
-		train.last_pos=train.path[train.max_index_on_track]
-		train.last_pos_prev=train.path[train.max_index_on_track-1]
-		--print("train is off-track (front), last positions kept at "..minetest.pos_to_string(train.last_pos).." / "..minetest.pos_to_string(train.last_pos_prev))
-	elseif train.min_index_on_track+1>train.index then --whoops, train went even more far. same behavior
-		train.savedpos_off_track_index_offset=train.index-train.min_index_on_track
-		train.last_pos=train.path[train.min_index_on_track+1]
-		train.last_pos_prev=train.path[train.min_index_on_track]
-		--print("train is off-track (back), last positions kept at "..minetest.pos_to_string(train.last_pos).." / "..minetest.pos_to_string(train.last_pos_prev))
-	else --regular case
-		train.savedpos_off_track_index_offset=nil
-		train.last_pos=train.path[math.floor(train.index+0.5)]
-		train.last_pos_prev=train.path[math.floor(train.index-0.5)]
-	end
-	return train.path
-end
-function advtrains.get_train_end_index(train)
-	return advtrains.get_real_path_index(train, train.trainlen or 2)--this function can be found inside wagons.lua since it's more related to wagons. we just set trainlen as pos_in_train
-end
-
-function advtrains.get_or_create_path(id, train)
-	if not train.path then return advtrains.pathpredict(id, train) end
-	return train.path
-end
-
-function advtrains.add_wagon_to_train(wagon, train_id, index)
-	local train=advtrains.trains[train_id]
-	if index then
-		table.insert(train.trainparts, index, wagon.unique_id)
-	else
-		table.insert(train.trainparts, wagon.unique_id)
-	end
-	--this is not the usual case!!!
-	--we may set initialized because the wagon has no chance to step()
-	wagon.initialized=true
-	--TODO is this art or can we throw it away?
-	advtrains.update_trainpart_properties(train_id)
-end
-function advtrains.update_trainpart_properties(train_id, invert_flipstate)
-	local train=advtrains.trains[train_id]
-	train.drives_on=advtrains.all_tracktypes
-	train.max_speed=100
-	local rel_pos=0
-	local count_l=0
-	for i, w_id in ipairs(train.trainparts) do
-		local wagon=nil
-		for _,iwagon in pairs(minetest.luaentities) do
-			if iwagon.is_wagon and iwagon.initialized and iwagon.unique_id==w_id then
-				if wagon then
-					--duplicate
-					iwagon.object:remove()
-				else
-					wagon=iwagon
-				end
-			end
-		end
-		if not wagon then
-			if advtrains.wagon_save[w_id] then
-				--spawn a new and initialize it with the properties from wagon_save
-				wagon=minetest.env:add_entity(train.last_pos, advtrains.wagon_save[w_id].entity_name):get_luaentity()
-				wagon:init_from_wagon_save(w_id)
-			end
-		end
-		if wagon then
-			rel_pos=rel_pos+wagon.wagon_span
-			wagon.train_id=train_id
-			wagon.pos_in_train=rel_pos
-			wagon.pos_in_trainparts=i
-			wagon.old_velocity_vector=nil
-			if wagon.is_locomotive then
-				count_l=count_l+1
-			end
-			if invert_flipstate then
-				wagon.wagon_flipped = not wagon.wagon_flipped
-			end
-			rel_pos=rel_pos+wagon.wagon_span
-			any_loaded=true
-			
-			if wagon.drives_on then
-				for k,_ in pairs(train.drives_on) do
-					if not wagon.drives_on[k] then
-						train.drives_on[k]=nil
-					end
-				end
-			end
-			train.max_speed=math.min(train.max_speed, wagon.max_speed)
-		else
-			print(w_id.." not loaded and no save available")
-			--what the hell...
-			table.remove(train.trainparts, pit)
-		end
-	end
-	train.trainlen=rel_pos
-	train.locomotives_in_train=count_l
-end
-
-function advtrains.split_train_at_wagon(wagon)
-	--get train
-	local train=advtrains.trains[wagon.train_id]
-	local real_pos_in_train=advtrains.get_real_path_index(train, wagon.pos_in_train)
-	local pos_for_new_train=advtrains.get_or_create_path(wagon.train_id, train)[math.floor(real_pos_in_train+wagon.wagon_span)]
-	local pos_for_new_train_prev=advtrains.get_or_create_path(wagon.train_id, train)[math.floor(real_pos_in_train-1+wagon.wagon_span)]
-	
-	--before doing anything, check if both are rails. else do not allow
-	if not pos_for_new_train then
-		print("split_train: pos_for_new_train not set")
-		return false
-	end
-	local node_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(pos_for_new_train), train.drives_on)
-	if not node_ok then
-		print("split_train: pos_for_new_train "..minetest.pos_to_string(advtrains.round_vector_floor_y(pos_for_new_train_prev)).." not loaded or is not a rail")
-		return false
-	end
-	
-	if not train.last_pos_prev then
-		print("split_train: pos_for_new_train_prev not set")
-		return false
-	end
-	
-	local prevnode_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(pos_for_new_train), train.drives_on)
-	if not prevnode_ok then
-		print("split_train: pos_for_new_train_prev "..minetest.pos_to_string(advtrains.round_vector_floor_y(pos_for_new_train_prev)).." not loaded or is not a rail")
-		return false
-	end
-	
-	--create subtrain
-	local newtrain_id=advtrains.create_new_train_at(pos_for_new_train, pos_for_new_train_prev)
-	local newtrain=advtrains.trains[newtrain_id]
-	--insert all wagons to new train
-	for k,v in ipairs(train.trainparts) do
-		if k>=wagon.pos_in_trainparts then
-			table.insert(newtrain.trainparts, v)
-			train.trainparts[k]=nil
-		end
-	end
-	--update train parts
-	advtrains.update_trainpart_properties(wagon.train_id)--atm it still is the desierd id.
-	advtrains.update_trainpart_properties(newtrain_id)
-	train.tarvelocity=0
-	newtrain.velocity=train.velocity
-	newtrain.tarvelocity=0
-end
-
---there are 4 cases:
---1/2. F<->R F<->R regular, put second train behind first
---->frontpos of first train will match backpos of second
---3.   F<->R R<->F flip one of these trains, take the other as new train
---->backpos's will match
---4.   R<->F F<->R flip one of these trains and take it as new parent
---->frontpos's will match
-
---true when trains are facing each other. needed on colliding.
--- check done by iterating paths and checking their direction
---returns nil when not on the same track at all OR when required path items are not generated. this distinction may not always be needed.
-function advtrains.trains_facing(train1, train2)
-	local sr_pos=train1.path[math.floor(train1.index)]
-	local sr_pos_p=train1.path[math.floor(train1.index)-1]
-
-	for i=advtrains.minN(train2.path), advtrains.maxN(train2.path) do
-		if vector.equals(sr_pos, train2.path[i]) then
-			if train2.path[i+1] and vector.equals(sr_pos_p, train2.path[i+1]) then return true end
-			if train2.path[i-1] and vector.equals(sr_pos_p, train2.path[i-1]) then return false end
-			return nil
-		end
-	end
-	return nil
-end
-
-function advtrains.spawn_couple_on_collide(id1, pos, id2, t1_is_backpos)
-	print("COLLISION: "..sid(id1).." and "..sid(id2).." at "..minetest.pos_to_string(pos)..", t1_is_backpos="..(t1_is_backpos and "true" or "false"))
-	--TODO:
-	local train1=advtrains.trains[id1]
-	local train2=advtrains.trains[id2]
-	
-	local found
-	for i=advtrains.minN(train1.path), advtrains.maxN(train1.path) do
-		if vector.equals(train1.path[i], pos) then
-			found=true
-		end
-	end
-	if not found then
-		print("Err: pos not in path")
-		return 
-	end
-	
-	local frontpos2=train2.path[math.floor(train2.detector_old_index)]
-	local backpos2=train2.path[math.floor(train2.detector_old_end_index)]
-	local t2_is_backpos
-	print("End positions: "..minetest.pos_to_string(frontpos2)..minetest.pos_to_string(backpos2))
-	
-	if vector.equals(frontpos2, pos) then
-		t2_is_backpos=false
-	elseif vector.equals(backpos2, pos) then
-		t2_is_backpos=true
-	else
-		print("Err: not a endpos")
-		return --the collision position is not the end position.
-	end
-	print("t2_is_backpos="..(t2_is_backpos and "true" or "false"))
-	
-	local t1_has_couple
-	if t1_is_backpos then
-		t1_has_couple=train1.couple_eid_back
-	else
-		t1_has_couple=train1.couple_eid_front
-	end
-	local t2_has_couple
-	if t2_is_backpos then
-		t2_has_couple=train2.couple_eid_back
-	else
-		t2_has_couple=train2.couple_eid_front
-	end
-	
-	if t1_has_couple then
-		if minetest.object_refs[t1_has_couple] then minetest.object_refs[t1_has_couple]:remove() end
-	end
-	if t2_has_couple then
-		if minetest.object_refs[t2_has_couple] then minetest.object_refs[t2_has_couple]:remove() end
-	end
-	local obj=minetest.add_entity(pos, "advtrains:couple")
-	if not obj then print("failed creating object") return end
-	local le=obj:get_luaentity()
-	le.train_id_1=id1
-	le.train_id_2=id2
-	le.train1_is_backpos=t1_is_backpos
-	le.train2_is_backpos=t2_is_backpos
-	--find in object_refs
-	for aoi, compare in pairs(minetest.object_refs) do
-		if compare==obj then
-			if t1_is_backpos then
-				train1.couple_eid_back=aoi
-			else
-				train1.couple_eid_front=aoi
-			end
-			if t2_is_backpos then
-				train2.couple_eid_back=aoi
-			else
-				train2.couple_eid_front=aoi
-			end
-		end
-	end
-	print("Couple entity:"..dump(le))
-	
-	--also TODO: integrate check_trainpartload into update_trainpart_properties. 
-end
---order of trains may be irrelevant in some cases. check opposite cases. TODO does this work?
---pos1 and pos2 are just needed to form a median.
-
-
-function advtrains.do_connect_trains(first_id, second_id)
-	local first_wagoncnt=#advtrains.trains[first_id].trainparts
-	local second_wagoncnt=#advtrains.trains[second_id].trainparts
-	
-	for _,v in ipairs(advtrains.trains[second_id].trainparts) do
-		table.insert(advtrains.trains[first_id].trainparts, v)
-	end
-	--kick it like physics (with mass being #wagons)
-	local new_velocity=((advtrains.trains[first_id].velocity*first_wagoncnt)+(advtrains.trains[second_id].velocity*second_wagoncnt))/(first_wagoncnt+second_wagoncnt)
-	advtrains.trains[second_id]=nil
-	advtrains.update_trainpart_properties(first_id)
-	advtrains.trains[first_id].velocity=new_velocity
-	advtrains.trains[first_id].tarvelocity=0
-end
-
-function advtrains.invert_train(train_id)
-	local train=advtrains.trains[train_id]
-	
-	local old_path=advtrains.get_or_create_path(train_id, train)
-	train.path={}
-	train.index= - advtrains.get_train_end_index(train)
-	train.velocity=-train.velocity
-	train.tarvelocity=-train.tarvelocity
-	for k,v in pairs(old_path) do
-		train.path[-k]=v
-	end
-	local old_trainparts=train.trainparts
-	train.trainparts={}
-	for k,v in ipairs(old_trainparts) do
-		table.insert(train.trainparts, 1, v)--notice insertion at first place
-	end
-	advtrains.update_trainpart_properties(train_id, true)
-end
-
-function advtrains.is_train_at_pos(pos)
-	--print("istrainat: pos "..minetest.pos_to_string(pos))
-	local checked_trains={}
-	local objrefs=minetest.get_objects_inside_radius(pos, 2)
-	for _,v in pairs(objrefs) do
-		local le=v:get_luaentity()
-		if le and le.is_wagon and le.initialized and le.train_id and not checked_trains[le.train_id] then
-			--print("istrainat: checking "..le.train_id)
-			checked_trains[le.train_id]=true
-			local path=advtrains.get_or_create_path(le.train_id, le:train())
-			if path then
-				--print("has path")
-				for i=math.floor(advtrains.get_train_end_index(le:train())+0.5),math.floor(le:train().index+0.5) do
-					if path[i] then
-						--print("has pathitem "..i.." "..minetest.pos_to_string(path[i]))
-						if vector.equals(advtrains.round_vector_floor_y(path[i]), pos) then
-							return true
-						end
-					end
-				end
-			end
-		end
-	end
-	return false
-end
-function advtrains.invalidate_all_paths()
-	--print("invalidating all paths")
-	for k,v in pairs(advtrains.trains) do
-		if v.index then
-			v.restore_add_index=v.index-math.floor(v.index+0.5)
-		end
-		v.path=nil
-		v.path_dist=nil
-		v.index=nil
-		v.min_index_on_track=nil
-		v.max_index_on_track=nil
-		
-		advtrains.detector.setup_restore()
-		v.detector_old_index=nil
-		v.detector_old_end_index=nil
-	end
-end
-
---not blocking trains group
-function advtrains.train_collides(node)
-	if node and minetest.registered_nodes[node.name] and minetest.registered_nodes[node.name].walkable then
-		if not minetest.registered_nodes[node.name].groups.not_blocking_trains then
-			return true
-		end
-	end
-	return false
-end
-
-local nonblocknodes={
-	"default:fence_wood",
-	"default:fence_acacia_wood",
-	"default:fence_aspen_wood",
-	"default:fence_pine_wood",
-	"default:fence_junglewood",
-	"default:torch",
-	
-	"default:sign_wall",
-	"signs:sign_wall",
-	"signs:sign_wall_blue",
-	"signs:sign_wall_brown",
-	"signs:sign_wall_orange",
-	"signs:sign_wall_green",
-	"signs:sign_yard",
-	"signs:sign_wall_white_black",
-	"signs:sign_wall_red",
-	"signs:sign_wall_white_red",
-	"signs:sign_wall_yellow",
-	"signs:sign_post",
-	"signs:sign_hanging",
-	
-	
-}
-minetest.after(0, function()
-	for _,name in ipairs(nonblocknodes) do
-		if minetest.registered_nodes[name] then
-			minetest.registered_nodes[name].groups.not_blocking_trains=1
-		end
-	end
-end)