Fix problems related to zero

Note: this fix only makes sure that the mod does not throw errors, but 
there are currently weird behaviors related to trainlogic.

2 files changed, 107 insertions, 108 deletions

diff --git a/advtrains/lzb.lua b/advtrains/lzb.lua
index 461e863..a34c2de 100644
--- a/advtrains/lzb.lua
+++ b/advtrains/lzb.lua
@@ -152,10 +152,12 @@ end
 -- Get the distance between the train and the LZB control point
 -- If not sure, use 3 as the parameter for lever level.
 function advtrains.lzb_get_distance_until_override(id, train, lever)
-	if lever == 4 then return nil end -- acceleration can not be forced by LZB
+	if lever == 4 then return nil end
 	local lzb = train.lzb
 	local i = 1
 	local ret = nil -- the value to return
+	local a = advtrains.get_acceleration(train, lever) -- Acceleration
+	local v0 = train.velocity
 	-- Remove LZB entries that are no longer valid
 	while i <= #lzb.oncoming do
 		if lzb.oncoming[i].idx < train.index then
@@ -170,12 +172,10 @@ function advtrains.lzb_get_distance_until_override(id, train, lever)
 	end
 	-- Now run through all the LZB entries and find the one that is nearest to the train
 	for _, it in ipairs(lzb.oncoming) do
-		local a = advtrains.get_acceleration(train, lever)
-		local v0 = train.velocity
 		local v1 = it.spd
 		if v1 and v1 <= v0 then
-			if a !~ 0 then local s = (v1*v1-v0*)/2/a else s = 0 end
-			local st
+			local s, st
+			if a ~= 0 then s = (v1*v1-v0*v0)/2/a else s = 0 end
 			if v0 > 3 then st = s + params.ADD_FAST
 			elseif v0 <= 0 then st = s + params.ADD_STAND
 			else st = s + params.ADD_SLOW
diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
index 12e1b93..b7a4528 100644
--- a/advtrains/trainlogic.lua
+++ b/advtrains/trainlogic.lua
@@ -37,6 +37,7 @@ local t_accel_all={
 	[0] = -10,
 	[1] = -3,
 	[2] = -0.5,
+	[3] = 0,
 	[4] = 0.5,
 }
 --acceleration per engine
@@ -44,6 +45,7 @@ local t_accel_eng={
 	[0] = 0,
 	[1] = 0,
 	[2] = 0,
+	[3] = 0,
 	[4] = 1.5,
 }
 
@@ -59,7 +61,7 @@ advtrains.mainloop_trainlogic=function(dtime)
 			advtrains.playersbypts[ptspos]=player
 		end
 	end
-	
+
 	if tp_player_tmr<=0 then
 		-- teleport players to their train every 2 seconds
 		for _, player in pairs(minetest.get_connected_players()) do
@@ -78,28 +80,28 @@ advtrains.mainloop_trainlogic=function(dtime)
 	5. make trains do other stuff (c)
 	]]--
 	local t=os.clock()
-	
+
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=k
 		advtrains.train_ensure_init(k, v)
 	end
-	
+
 	advtrains.lock_path_inval = true
-	
+
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=k
 		advtrains.train_step_b(k, v, dtime)
 	end
-	
+
 	for k,v in pairs(advtrains.trains) do
 		advtrains.atprint_context_tid=k
 		advtrains.train_step_c(k, v, dtime)
 	end
-	
+
 	advtrains.lock_path_inval = false
-	
+
 	advtrains.atprint_context_tid=nil
-	
+
 	atprintbm("trainsteps", t)
 	endstep()
 end
@@ -236,7 +238,7 @@ function advtrains.train_ensure_init(id, train)
 		atwarn(debug.traceback())
 		return nil
 	end
-	
+
 	train.dirty = true
 	if train.no_step then return nil end
 
@@ -245,12 +247,12 @@ function advtrains.train_ensure_init(id, train)
 	assertdef(train, "acceleration", 0)
 	assertdef(train, "id", id)
 	assertdef(train, "ctrl", {})
-	
-	
+
+
 	if not train.drives_on or not train.max_speed then
 		advtrains.update_trainpart_properties(id)
 	end
-	
+
 	--restore path
 	if not train.path then
 		if not train.last_pos then
@@ -272,9 +274,9 @@ function advtrains.train_ensure_init(id, train)
 			Result: log flood.
 			]]
 		end
-		
+
 		local result = advtrains.path_create(train, train.last_pos, train.last_connid or 1, train.last_frac or 0)
-		
+
 		if result==false then
 			atlog("Train",id,": Restoring path failed, node at",train.last_pos,"is gone! Train will be disabled. You can try to place a rail at this position and restart the server.")
 			train.no_step = true
@@ -288,31 +290,31 @@ function advtrains.train_ensure_init(id, train)
 		end
 		-- by now, we should have a working initial path
 		train.wait_for_path = false
-		
+
 		advtrains.update_trainpart_properties(id)
 		recalc_end_index(train)
-		
+
 		--atdebug("Train",id,": Successfully restored path at",train.last_pos," connid",train.last_connid," frac",train.last_frac)
-		
+
 		-- run on_new_path callbacks
 		run_callbacks_new_path(id, train)
 	end
-	
+
 	train.dirty = false -- TODO einbauen!
 	return true
 end
 
 function advtrains.train_step_b(id, train, dtime)
 	if train.no_step or train.wait_for_path or not train.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, atfloor(train.index + 2))
 	advtrains.path_get(train, atfloor(train.end_index - 1))
-	
+
 	--- 3. handle velocity influences ---
 	local train_moves=(train.velocity~=0)
 	local tarvel_cap = train.speed_restriction
-	
+
 	if train.recently_collided_with_env then
 		tarvel_cap=0
 		if not train_moves then
@@ -322,26 +324,26 @@ function advtrains.train_step_b(id, train, dtime)
 	if train.locomotives_in_train==0 then
 		tarvel_cap=0
 	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(train, atfloor(train.index))
 	if train_pos then
 		t_info=t_info.." @"..minetest.pos_to_string(train_pos)
 		--atprint("train_pos:",train_pos)
 	end
-	
+
 	--apply off-track handling:
 	local front_off_track = train.index>train.path_trk_f
 	local back_off_track=train.end_index<train.path_trk_b
 	train.off_track = front_off_track or back_off_track
-	
+
 	if front_off_track then
 		tarvel_cap=0
 	end
 	if back_off_track then -- eventually overrides front_off_track restriction
 		tarvel_cap=1
 	end
-	
+
 	-- Driving control rework:
 	--[[
 	Items are only defined when something is controlling them.
@@ -353,10 +355,10 @@ function advtrains.train_step_b(id, train, dtime)
 	}
 	The code here determines the precedence and writes the final control into train.lever
 	]]
-	
+
 	--interpret ATC command and apply auto-lever control when not actively controlled
 	local trainvelocity = train.velocity
-	
+
 	if train.ctrl.user then
 		advtrains.atc.train_reset_command(train)
 	else
@@ -387,7 +389,7 @@ function advtrains.train_step_b(id, train, dtime)
 		elseif train.atc_delay then
 			train.atc_delay = nil
 		end
-		
+
 		train.ctrl.atc = nil
 		if train.tarvelocity and train.tarvelocity>trainvelocity then
 			train.ctrl.atc=4
@@ -404,20 +406,13 @@ function advtrains.train_step_b(id, train, dtime)
 			end
 		end
 	end
-	
+
 	--if tarvel_cap and train.tarvelocity and tarvel_cap<train.tarvelocity then
 	--	train.tarvelocity=tarvel_cap
 	--end
-	
-	local tmp_lever
 
-	tmp_lever = train.ctrl.user or train.ctrl.atc
+	local tmp_lever = (train.ctrl.user or train.ctrl.atc) or 3
 
-	if not tmp_lever then
-		-- if there was no control at all, default to 3
-		tmp_lever = 3
-	end
-	
 	if tarvel_cap and trainvelocity>tarvel_cap then
 		tmp_lever = 0
 	end
@@ -425,8 +420,8 @@ function advtrains.train_step_b(id, train, dtime)
 	train.lever = tmp_lever
 
 	--- 4a. Get the correct lever based on LZB ---
-	tmp_lever = tmp_lever + 1
 	local lzblever = tmp_lever
+	tmp_lever = tmp_lever + 1
 	local s, s1, s2, v0, v1, v2, t1, t2, a1, a2
 	repeat
 		tmp_lever = lzblever
@@ -442,27 +437,31 @@ function advtrains.train_step_b(id, train, dtime)
 		v2 = v0 + a1 * dtime
 		if train.tarvelocity then v2 = math.min(v2, train.tarvelocity) end
 		v2 = math.min(v2, (train.max_speed or 10))
-		s = (v2*v2 - v0*v0)/2/a1
+		if a1 == 0 then -- if there is no acceleration, simply s = v * t
+			s = v0 * dtime
+		else
+			s = (v2*v2 - v0*v0)/2/a1
+		end
 		a2 = a1
 		lzblever = tmp_lever
 	else
-		if (-v0*v0)/2/a1 < s1 then -- train stops in front of LZB control
+		if (a1 ~= 0) and ((-v0*v0)/2/a1 < s1) then -- train stops in front of LZB control
 			v2 = 0
 			s = (-v0*v0)/2/a1
 		else -- Train continues and further control seems to be taken
 			v1 = math.sqrt(2*s1*a1 + v0*v0)
 			if train.tarvelocity then v1 = math.min(v1, train.tarvelocity) end
 			v1 = math.min(v1, (train.max_speed or 10))
-			t1 = (v1-v0)/a1
+			if a1 == 0 then t1 = s1/v1 else t1 = (v1-v0)/a1 end
 			t2 = dtime - t1
 			if t2 > 0 then -- if the train can reach s2
 				v2 = a2*t2+v1
 				if v2 < 0 then v2 = 0 end -- Force velocity to be at least 0
-				s2 = (v2*v2-v1*v1)/2/a2
+				if a2 == 0 then s2 = v2 * t2 else s2 = (v2*v2-v1*v1)/2/a2 end
 				s = s1 + s2
 			else -- the train might not reach s2 due to some limits
 				v2 = v1
-				s = (v1*v1 - v0*v0)/2/a1
+				if a1 == 0 then s = v2 * dtime else s = (v1*v1 - v0*v0)/2/a1 end
 			end
 		end
 	end
@@ -478,47 +477,47 @@ function advtrains.train_step_b(id, train, dtime)
 
 	--debugging code
 	--train.debug = atdump(train.ctrl).."step_dist: "..math.floor(distance*1000)
-	
+
 	train.index=train.index+distance
-	
+
 	recalc_end_index(train)
 
 end
 
 function advtrains.train_step_c(id, train, dtime)
 	if train.no_step or train.wait_for_path or not train.path then return end
-	
+
 	-- all location/extent-critical actions have been done.
 	-- calculate the new occupation window
 	run_callbacks_update(id, train)
-	
+
 	-- Return if something(TM) damaged the path
 	if train.no_step or train.wait_for_path or not train.path then return end
-	
+
 	advtrains.path_clear_unused(train)
-	
+
 	advtrains.path_setrestore(train)
-	
+
 	-- less important stuff
-	
+
 	train.check_trainpartload=(train.check_trainpartload or 0)-dtime
 	if train.check_trainpartload<=0 then
 		advtrains.spawn_wagons(id)
 		train.check_trainpartload=2
 	end
-	
+
 	--- 8. check for collisions with other trains and damage players ---
-	
+
 	local train_moves=(train.velocity~=0)
-	
+
 	--- Check whether this train can be coupled to another, and set couple entities accordingly
 	if not train.was_standing and not train_moves then
 		advtrains.train_check_couples(train)
 	end
 	train.was_standing = not train_moves
-	
+
 	if train_moves then
-		
+
 		local collided = false
 		local coll_grace=1
 		local collindex = advtrains.path_get_index_by_offset(train, train.index, -coll_grace)
@@ -574,7 +573,7 @@ function advtrains.train_step_c(id, train, dtime)
 			if is_loaded_area then
 				local objs = minetest.get_objects_inside_radius(rcollpos, 2)
 				for _,obj in ipairs(objs) do
-					if not obj:is_player() and obj:get_armor_groups().fleshy and obj:get_armor_groups().fleshy > 0 
+					if not obj:is_player() and obj:get_armor_groups().fleshy and obj:get_armor_groups().fleshy > 0
 							and obj:get_luaentity() and obj:get_luaentity().name~="signs:text" then
 						obj:punch(obj, 1, { full_punch_interval = 1.0, damage_groups = {fleshy = 1000}, }, nil)
 					end
@@ -637,7 +636,7 @@ local function tnc_call_leave_callback(pos, train_id, train, index)
 	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_leave then
 		mregnode.advtrains.on_train_leave(pos, train_id, train, index)
 	end
-	
+
 	-- call other registered callbacks
 	run_callbacks_leave_node(pos, train_id, train, index)
 end
@@ -649,7 +648,7 @@ function advtrains.tnc_call_approach_callback(pos, train_id, train, index, lzbda
 	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_approach then
 		mregnode.advtrains.on_train_approach(pos, train_id, train, index, lzbdata)
 	end
-	
+
 	-- call other registered callbacks
 	run_callbacks_approach_node(pos, train_id, train, index, lzbdata)
 end
@@ -708,68 +707,68 @@ end)
 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
-	
+
 	local t={}
 	t.id = new_id
-	
+
 	t.last_pos=pos
 	t.last_connid=connid
 	t.last_frac=ioff
-	
+
 	--t.tarvelocity=0
 	t.velocity=0
 	t.trainparts=trainparts
-	
+
 	advtrains.trains[new_id] = t
 	--atdebug("Created new train:",t)
-	
+
 	if not advtrains.train_ensure_init(new_id, advtrains.trains[new_id]) then
 		atwarn("create_new_train_at",pos,connid,"failed! This might lead to temporary bugs.")
 		return
 	end
-	
+
 	run_callbacks_create(new_id, advtrains.trains[new_id])
-	
+
 	return new_id
 end
 
 function advtrains.remove_train(id)
 	local train = advtrains.trains[id]
-	
+
 	if not advtrains.train_ensure_init(id, train) then
 		atwarn("remove_train",id,"failed! This might lead to temporary bugs.")
 		return
 	end
-	
+
 	run_callbacks_remove(id, train)
-	
+
 	advtrains.path_invalidate(train)
 	advtrains.couple_invalidate(train)
-	
+
 	local tp = train.trainparts
 	--atdebug("Removing train",id,"leftover trainparts:",tp)
-	
+
 	advtrains.trains[id] = nil
-	
+
 	return tp
-	
+
 end
 
 
 function advtrains.add_wagon_to_train(wagon_id, train_id, index)
 	local train=advtrains.trains[train_id]
-	
+
 	if not advtrains.train_ensure_init(train_id, train) then
 		atwarn("Train",train_id,"is not initialized! Operation aborted!")
 		return
 	end
-	
+
 	if index then
 		table.insert(train.trainparts, index, wagon_id)
 	else
 		table.insert(train.trainparts, wagon_id)
 	end
-	
+
 	advtrains.update_trainpart_properties(train_id)
 	recalc_end_index(train)
 	run_callbacks_update(train_id, train)
@@ -784,14 +783,14 @@ function advtrains.update_trainpart_properties(train_id, invert_flipstate)
 	--FIX: deep-copy the table!!!
 	train.max_speed=20
 	train.extent_h = 0;
-	
+
 	local rel_pos=0
 	local count_l=0
 	local shift_dcpl_lock=false
 	for i, w_id in ipairs(train.trainparts) do
-		
+
 		local data = advtrains.wagons[w_id]
-		
+
 		-- 1st: update wagon data (pos_in_train a.s.o)
 		if data then
 			local wagon = advtrains.wagon_prototypes[data.type or data.entity_name]
@@ -812,7 +811,7 @@ function advtrains.update_trainpart_properties(train_id, invert_flipstate)
 				shift_dcpl_lock, data.dcpl_lock = data.dcpl_lock, shift_dcpl_lock
 			end
 			rel_pos=rel_pos+wagon.wagon_span
-			
+
 			if wagon.drives_on then
 				for k,_ in pairs(train.drives_on) do
 					if not wagon.drives_on[k] then
@@ -834,7 +833,7 @@ local ablkrng = minetest.settings:get("active_block_range")*16
 -- Called from train_step_*(), not required to check init.
 function advtrains.spawn_wagons(train_id)
 	local train = advtrains.trains[train_id]
-	
+
 	for i = 1, #train.trainparts do
 		local w_id = train.trainparts[i]
 		local data = advtrains.wagons[w_id]
@@ -847,14 +846,14 @@ function advtrains.spawn_wagons(train_id)
 				-- eventually need to spawn new object. check if position is loaded.
 				local index = advtrains.path_get_index_by_offset(train, train.index, -data.pos_in_train)
 				local pos   = advtrains.path_get(train, atfloor(index))
-				
+
 				local spawn = false
 				for _,p in pairs(minetest.get_connected_players()) do
 					if vector.distance(p:get_pos(),pos)<=ablkrng then
 						spawn = true
 					end
 				end
-				
+
 				if spawn then
 					local wt = advtrains.get_wagon_prototype(data)
 					local wagon = minetest.add_entity(pos, wt):get_luaentity()
@@ -897,11 +896,11 @@ function advtrains.split_train_at_index(train, index)
 	advtrains.update_trainpart_properties(train_id)
 	recalc_end_index(train)
 	run_callbacks_update(train_id, train)
-	
+
 	--create subtrain
 	local newtrain_id=advtrains.create_new_train_at(pos, connid, frac, tp)
 	local newtrain=advtrains.trains[newtrain_id]
-	
+
 	newtrain.velocity=train.velocity
 	return newtrain_id -- return new train ID, so new train can be manipulated
 
@@ -938,7 +937,7 @@ local function createcouple(pos, train1, t1_is_front, train2, t2_is_front)
 	else
 		train2.cpl_back = obj
 	end
-	
+
 end
 
 function advtrains.train_check_couples(train)
@@ -1029,7 +1028,7 @@ end
 
 function advtrains.do_connect_trains(first_id, second_id, vel)
 	local first, second=advtrains.trains[first_id], advtrains.trains[second_id]
-	
+
 	if not advtrains.train_ensure_init(first_id, first) then
 		atwarn("Train",first_id,"is not initialized! Operation aborted!")
 		return
@@ -1038,18 +1037,18 @@ function advtrains.do_connect_trains(first_id, second_id, vel)
 		atwarn("Train",second_id,"is not initialized! Operation aborted!")
 		return
 	end
-	
+
 	local first_wagoncnt=#first.trainparts
 	local second_wagoncnt=#second.trainparts
-	
+
 	for _,v in ipairs(second.trainparts) do
 		table.insert(first.trainparts, v)
 	end
-	
+
 	advtrains.remove_train(second_id)
-	
+
 	first.velocity= vel or 0
-	
+
 	advtrains.update_trainpart_properties(first_id)
 	advtrains.couple_invalidate(first)
 	return true
@@ -1057,14 +1056,14 @@ end
 
 function advtrains.invert_train(train_id)
 	local train=advtrains.trains[train_id]
-	
+
 	if not advtrains.train_ensure_init(train_id, train) then
 		atwarn("Train",train_id,"is not initialized! Operation aborted!")
 		return
 	end
-	
+
 	advtrains.path_setrestore(train, true)
-	
+
 	-- rotate some other stuff
 	if train.door_open then
 		train.door_open = - train.door_open
@@ -1072,20 +1071,20 @@ function advtrains.invert_train(train_id)
 	if train.atc_command then
 		train.atc_arrow = not train.atc_arrow
 	end
-	
+
 	advtrains.path_invalidate(train, true)
 	advtrains.couple_invalidate(train)
-	
+
 	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)
-	
+
 	-- recalculate path
 	advtrains.train_ensure_init(train_id, train)
-	
+
 	-- If interlocking present, check whether this train is in a section and then set as shunt move after reversion
 	if advtrains.interlocking and train.il_sections and #train.il_sections > 0 then
 		train.is_shunt = true
@@ -1114,7 +1113,7 @@ function advtrains.invalidate_all_paths(pos)
 	else
 		tab = advtrains.trains
 	end
-	
+
 	for id, _ in pairs(tab) do
 		advtrains.invalidate_path(id)
 	end
@@ -1146,7 +1145,7 @@ local nonblocknodes={
 	"default:fence_junglewood",
 	"default:torch",
 	"bones:bones",
-	
+
 	"default:sign_wall",
 	"signs:sign_wall",
 	"signs:sign_wall_blue",
@@ -1160,8 +1159,8 @@ local nonblocknodes={
 	"signs:sign_wall_yellow",
 	"signs:sign_post",
 	"signs:sign_hanging",
-	
-	
+
+
 }
 minetest.after(0, function()
 	for _,name in ipairs(nonblocknodes) do