Added on_train_approach callback, non-permanent external LZB brakepoints and basis for "stop rails"

Stop rails ATM use the aforementioned things to add a pointwise "2" speed restriction. Seems to work.

advtrains/api_doc.txt

@@ -178,5 +178,10 @@ minetest.register_node(nodename, {
 		^- called when a train enters the rail
 		on_train_leave=function(pos, train_id) end
 		^- called when a train leaves the rail
+		
+		-- The following function is only in effect when interlocking is enabled:
+		on_train_approach = function(pos, train_id, train, index)
+		^- called when a train is approaching this position, called exactly once for every path recalculation (which can happen at any time)
+		^- This is called so that if the train would start braking now, it would come to halt about(wide approx) 5 nodes before the rail.
 	}
 })

advtrains/init.lua

@@ -194,6 +194,9 @@ dofile(advtrains.modpath.."/passive.lua")
 
 --load/save
 
+-- backup variables, used if someone should accidentally delete a sub-mod
+local MDS_interlocking
+
 
 advtrains.fpath=minetest.get_worldpath().."/advtrains"
 dofile(advtrains.modpath.."/log.lua")
@@ -219,6 +222,8 @@ function advtrains.avt_load()
 				advtrains.atc.load_data(tbl.atc)
 				if advtrains.interlocking then
 					advtrains.interlocking.db.load(tbl.interlocking)
+				else
+					MDS_interlocking = tbl.interlocking
 				end
 				--remove wagon_save entries that are not part of a train
 				local todel=advtrains.merge_tables(advtrains.wagon_save)
@@ -318,6 +323,8 @@ advtrains.avt_save = function(remove_players_from_wagons)
 	local il_save
 	if advtrains.interlocking then
 		il_save = advtrains.interlocking.db.save()
+	else
+		il_save = MDS_interlocking
 	end
 	local save_tbl={
 		trains = tmp_trains,

advtrains_interlocking/lzb.lua

@@ -1,6 +1,18 @@
 -- lzb.lua
 -- Enforced and/or automatic train override control, obeying signals
 
+
+local function approach_callback(parpos, train_id, train, index)
+	local pos = advtrains.round_vector_floor_y(parpos)
+
+	local node=pnode or advtrains.ndb.get_node(pos)
+	local ndef=minetest.registered_nodes[node.name]
+	if ndef and ndef.advtrains and ndef.advtrains.on_train_approach then
+		ndef.advtrains.on_train_approach(pos, train_id, train, index)
+	end
+end
+
+
 --[[
 Documentation of train.lzb table
 train.lzb = {
@@ -10,9 +22,13 @@ train.lzb = {
 	travwspd = warning speed res.
 	oncoming = table containing oncoming signals, in order of appearance on the path
 		{
-			pos = position of the signal (not the IP!)
+			pos = position of the signal (not the IP!). Can be nil
 			idx = where this is on the path
 			spd = speed allowed to pass (determined dynamically)
+			npr = <boolean> "No permanent restriction" If true, this is only a punctual restriction.
+				speed_restriction is not set then, and train can accelerate after passing point
+				This is (as of Nov 2017) used by "lines" to brake the train down to 2 when approaching a stop
+				The actual "stop" command is given when the train passes the rail (on_train_enter callback)
 		}
 }
 each step, for every item in "oncoming", we need to determine the location to start braking (+ some safety margin)
@@ -67,6 +83,9 @@ local function look_ahead(id, train)
 				spd = 0,
 			})
 		else
+			-- run callback, if exists
+			approach_callback(pos, id, train, trav)
+			
 			-- check for signal
 			local asp, spos = il.db.get_ip_signal_asp(pts, cn)
 			--atdebug("trav: ",pos, cn, asp, spos, "travsht=", lzb.travsht)
@@ -207,6 +226,18 @@ function advtrains.interlocking.lzb_invalidate(train)
 	invalidate(train)
 end
 
+-- Add an (extra) lzb control point that is not a permanent restriction (see above)
+-- (permanent restrictions are only to be imposed by signal ip's)
+function advtrains.interlocking.lzb_add_oncoming_npr(train, idx, spd)
+	local lzb = train.lzb
+	
+	table.insert(lzb.oncoming, {
+					idx = idx,
+					spd = spd,
+					npr = true,
+				})
+end
+
 
 advtrains.te_register_on_new_path(function(id, train)
 	invalidate(train)

advtrains_line_automation/depends.txt

@@ -0,0 +1,2 @@
+advtrains_interlocking
+advtrains_train_track

advtrains_line_automation/init.lua

@@ -0,0 +1,17 @@
+-- Advtrains line automation system
+
+advtrains.lines = {}
+
+
+local modpath = minetest.get_modpath(minetest.get_current_modname()) .. DIR_DELIM
+
+dofile(modpath.."stoprail.lua")
+
+
+function advtrains.lines.load(data)
+	
+end
+
+function advtrains.lines.save()
+	return {}
+end

advtrains_line_automation/readme.txt

@@ -0,0 +1,5 @@
+== advtrains_line_automation
+This mod provides an extension to the interlocking system which allows to automatically operate trains on train lines.
+
+This extension makes use of the table
+advtrains.lines

advtrains_line_automation/stoprail.lua

@@ -0,0 +1,39 @@
+-- stoprail.lua
+-- adds "stop rail". Recognized by lzb. (part of behavior is implemented there)
+
+
+local adefunc = function(def, preset, suffix, rotation)
+		return {
+			after_place_node=function(pos)
+				
+			end,
+			after_dig_node=function(pos)
+				
+			end,
+			on_receive_fields = function(pos, formname, fields, player)
+				
+			end,
+			advtrains = {
+				on_train_enter = function(pos, train_id)
+				end,
+				on_train_approach = function(pos,train_id, train, index)
+					atdebug("Train approaches stop:",pos,train_id,index)
+					--TODO conditions
+					advtrains.interlocking.lzb_add_oncoming_npr(train, index, 2)
+				end,
+			},
+		}
+end
+
+
+
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains_line_automation:dtrack_stop",
+	texture_prefix="advtrains_dtrack_stop",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_shared_stop.png",
+	description="Station/Stop Rail",
+	formats={},
+	get_additional_definiton = adefunc,
+}, advtrains.trackpresets.t_30deg_straightonly)