round speed limit downward if needed; add basic distant signal implementation

6 files changed, 116 insertions, 10 deletions

diff --git a/advtrains_interlocking/database.lua b/advtrains_interlocking/database.lua
index a35d446..ee21db9 100644
--- a/advtrains_interlocking/database.lua
+++ b/advtrains_interlocking/database.lua
@@ -195,6 +195,8 @@ TCB data structure
 	signal_name = <string> -- The human-readable name of the signal, only for documenting purposes
 	routes = { <route definition> } -- a collection of routes from this signal
 	route_auto = <boolean> -- When set, we will automatically re-set the route (designated by routeset)
+	distant = { <sigd1> ... } -- a collection of sigd that points to a side of a TCB with a distant signal for this current signal.
+	distant_of = { <sigd>, <index> } -- the reverse of the above field, along with the index of the entry in the list (for easier lookup)
 },
 -- This is the "B" side of the TCB
 [2] = { -- Variant: end of track-circuited area (initial state of TC)
diff --git a/advtrains_interlocking/distant_signals.lua b/advtrains_interlocking/distant_signals.lua
new file mode 100644
index 0000000..0da1c10
--- /dev/null
+++ b/advtrains_interlocking/distant_signals.lua
@@ -0,0 +1,83 @@
+local interlocking = advtrains.interlocking
+local ildb = advtrains.interlocking.db
+
+local function update_distant(tcbs)
+	if not (tcbs and tcbs.signal) then return end
+	if not tcbs.aspect then tcbs.aspect = table.copy(interlocking.DANGER) end
+	local asp = tcbs.aspect
+	if tcbs.distant_of then
+		asp.dst = (ildb.get_tcbs(tcbs.distant_of[1]).aspect or interlocking.DANGER).main
+	end
+	interlocking.update_signal_aspect(tcbs)
+	if tcbs.distant then
+		local dst = tcbs.distant
+		for i = 1, #dst do
+			local s = ildb.get_tcbs(dst[i])
+			if not s.aspect then s.aspect = table.copy(interlocking.DANGER) end
+			s.aspect.dst = asp.main
+			interlocking.update_signal_aspect(s)
+		end
+	end
+end
+
+local function unassign_distant(dsts)
+	if not dsts then return end
+	local dof = dsts.distant_of
+	if not dof then return end
+	if dsts.signal and dsts.aspect then
+		dsts.aspect.dst = nil
+		interlocking.update_signal_aspect(dsts)
+	end
+	local sigd, idx = dof[1], dof[2]
+	local tcbs = ildb.get_tcbs(sigd)
+	local dst = tcbs.distant
+	dsts.distant_of = nil
+	if idx == #dst then
+		dst[#dst] = nil
+	else
+		local ent = dst[#dst]
+		dst[idx] = ent
+		dst[#dst] = nil
+		local repl = ildb.get_tcbs(ent)
+		repl.distant_of[2] = idx
+	end
+end
+
+local function assign_distant(sigd, dstd)
+	if not sigd then return end
+	if not dstd then return end
+	local tcbs = ildb.get_tcbs(sigd)
+	local dsts = ildb.get_tcbs(dstd)
+	unassign_distant(dsts)
+	if not (tcbs.signal and dsts.signal) then return end
+	local dst = tcbs.distant
+	if not dst then
+		dst = {}
+		tcbs.distant = dst
+	end
+	local newidx = #dst+1
+	dsts.distant_of = {sigd, newidx}
+	dst[newidx] = dstd
+	update_distant(dsts)
+end
+
+local function remove_distant(tcbs)
+	if not tcbs then return end
+	if tcbs.distant_of then
+		unassign_distant(tcbs)
+	end
+	if tcbs.distant then
+		local dst = tcbs.distant
+		for i = #dst, 1, -1 do
+			local s = ildb.get_tcbs(dst[i])
+			unassign_distant(s)
+		end
+	end
+end
+
+interlocking.distant = {
+	assign = assign_distant,
+	unassign = unassign_distant,
+	remove = remove_distant,
+	update = update_distant,
+}
diff --git a/advtrains_interlocking/init.lua b/advtrains_interlocking/init.lua
index a2f5882..cfbb8e5 100644
--- a/advtrains_interlocking/init.lua
+++ b/advtrains_interlocking/init.lua
@@ -16,6 +16,7 @@ dofile(modpath.."database.lua")
 dofile(modpath.."signal_api.lua")
 dofile(modpath.."demosignals.lua")
 dofile(modpath.."train_sections.lua")
+dofile(modpath.."distant_signals.lua")
 dofile(modpath.."route_prog.lua")
 dofile(modpath.."routesetting.lua")
 dofile(modpath.."tcb_ts_ui.lua")
diff --git a/advtrains_interlocking/routesetting.lua b/advtrains_interlocking/routesetting.lua
index 67efaea..d801608 100644
--- a/advtrains_interlocking/routesetting.lua
+++ b/advtrains_interlocking/routesetting.lua
@@ -44,7 +44,7 @@ function ilrs.set_route(signal, route, try)
 	local i = 1
 	local rtename = route.name
 	local signalname = ildb.get_tcbs(signal).signal_name
-	local c_tcbs, c_ts_id, c_ts, c_rseg, c_lckp
+	local c_tcbs, c_ts_id, c_ts, c_rseg, c_lckp, p_ssigd
 	while c_sigd and i<=#route do
 		c_tcbs = ildb.get_tcbs(c_sigd)
 		if not c_tcbs then
@@ -112,9 +112,16 @@ function ilrs.set_route(signal, route, try)
 			}
 			if c_tcbs.signal then
 				c_tcbs.route_committed = true
-				c_tcbs.aspect = route.aspect or advtrains.interlocking.GENERIC_FREE
+				local asp = route.aspect or advtrains.interlocking.GENERIC_FREE
+				asp.dst = nil
+				c_tcbs.aspect = asp
 				c_tcbs.route_origin = signal
-				advtrains.interlocking.update_signal_aspect(c_tcbs)
+				advtrains.interlocking.distant.update(c_tcbs)
+				-- Update the previous distant signal
+				if p_ssigd then
+					advtrains.interlocking.distant.assign(c_sigd, p_ssigd)
+				end
+				p_ssigd = c_sigd
 			end
 		end
 		-- advance
@@ -122,6 +129,17 @@ function ilrs.set_route(signal, route, try)
 		c_sigd = c_rseg.next
 		i = i + 1
 	end
+
+	if c_sigd and p_ssigd then
+		local e_tcbs = ildb.get_tcbs(c_sigd)
+		if e_tcbs.signal then
+			if p_stcb then
+				p_stcb.aspect.dst = (e_tcbs.aspect or advtrains.interlocking.DANGER).main
+				advtrains.interlocking.update_signal_aspect(p_stcb)
+			end
+		end
+		advtrains.interlocking.distant.assign(c_sigd, p_ssigd)
+	end
 	
 	return true
 end
diff --git a/advtrains_interlocking/tcb_ts_ui.lua b/advtrains_interlocking/tcb_ts_ui.lua
index 34fbf7f..2425bf2 100755
--- a/advtrains_interlocking/tcb_ts_ui.lua
+++ b/advtrains_interlocking/tcb_ts_ui.lua
@@ -778,6 +778,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 				ildb.set_sigd_for_signal(signal_pos, nil)
 				tcbs.signal = nil
 				tcbs.aspect = nil
+				advtrains.interlocking.distant.remove(tcbs)
 				minetest.close_formspec(pname, formname)
 				minetest.chat_send_player(pname, "Signal has been unassigned. Name and routes are kept for reuse.")
 				return
diff --git a/advtrains_signals_ks/init.lua b/advtrains_signals_ks/init.lua
index a1f056c..3a2f4d0 100755
--- a/advtrains_signals_ks/init.lua
+++ b/advtrains_signals_ks/init.lua
@@ -4,15 +4,17 @@
 -- Note that the group value of advtrains_signal is 2, which means "step 2 of signal capabilities"
 -- advtrains_signal=1 is meant for signals that do not implement set_aspect.
 
-local supported_speed_limits = {
-	[4] = true, [6] = true, [8] = true, [12] = true, [16] = true
-}
+local function asp_to_zs3type(asp)
+	local n = tonumber(asp)
+	if not n or n < 4 then return "off" end
+	if n < 8 then return 2*math.floor(n/2) end
+	return math.min(16,4*math.floor(n/4))
+end
 
 local function setzs3(msp, lim, rot)
 	local pos = {x = msp.x, y = msp.y+1, z = msp.z}
 	local node = advtrains.ndb.get_node(pos)
-	local asp = lim
-	if not asp or not supported_speed_limits[lim] then asp = "off" end
+	local asp = asp_to_zs3type(lim)
 	if node.name:find("^advtrains_signals_ks:zs3_") then
 		advtrains.ndb.swap_node(pos, {name="advtrains_signals_ks:zs3_"..asp.."_"..rot, param2 = node.param2})
 	end
@@ -31,8 +33,7 @@ end
 local function setzs3v(msp, lim, rot)
 	local pos = {x = msp.x, y = msp.y-1, z = msp.z}
 	local node = advtrains.ndb.get_node(pos)
-	local asp = lim
-	if not asp or not supported_speed_limits[lim] then asp = "off" end
+	local asp = asp_to_zs3type(lim)
 	if node.name:find("^advtrains_signals_ks:zs3v_") then
 		advtrains.ndb.swap_node(pos, {name="advtrains_signals_ks:zs3v_"..asp.."_"..rot, param2 = node.param2})
 	end