Do not modify rails that should not be modified

... when placing tracks, such as slopes
Fixes slopes being replaced by curves.
Also, check the node below for connection (does not check rely, but that would be uneccessary)

1 files changed, 39 insertions, 13 deletions

diff --git a/advtrains/trackplacer.lua b/advtrains/trackplacer.lua
index f200638..9d207e6 100644
--- a/advtrains/trackplacer.lua
+++ b/advtrains/trackplacer.lua
@@ -65,16 +65,26 @@ end
 		-> set straight
 ]]
 
-function tp.find_already_connected(pos)--TODO vertical calculations(check node below)
-	local function istrackandbc(pos, conn)
-		local cnode=minetest.get_node(advtrains.dirCoordSet(pos, conn))
-		local bconn=(conn+8)%16
-		if advtrains.is_track_and_drives_on(cnode.name, advtrains.all_tracktypes) then
-			local cconn1, cconn2=advtrains.get_track_connections(cnode.name, cnode.param2)
-			return cconn1==bconn or cconn2==bconn
-		end
-		return false
+local function istrackandbc(pos_p, conn)
+	local tpos = pos_p
+	local cnode=minetest.get_node(advtrains.dirCoordSet(tpos, conn))
+	local bconn=(conn+8)%16
+	if advtrains.is_track_and_drives_on(cnode.name, advtrains.all_tracktypes) then
+		local cconn1, cconn2=advtrains.get_track_connections(cnode.name, cnode.param2)
+		return cconn1==bconn or cconn2==bconn
+	end
+	--try the same 1 node below
+	tpos = {x=tpos.x, y=tpos.y-1, z=tpos.z}
+	cnode=minetest.get_node(advtrains.dirCoordSet(tpos, conn))
+	bconn=(conn+8)%16
+	if advtrains.is_track_and_drives_on(cnode.name, advtrains.all_tracktypes) then
+		local cconn1, cconn2=advtrains.get_track_connections(cnode.name, cnode.param2)
+		return cconn1==bconn or cconn2==bconn
 	end
+	return false
+end
+
+function tp.find_already_connected(pos)
 	local dnode=minetest.get_node(pos)
 	local dconn1, dconn2=advtrains.get_track_connections(dnode.name, dnode.param2)
 	if istrackandbc(pos, dconn1) and istrackandbc(pos, dconn2) then return dconn1, dconn2
@@ -95,6 +105,14 @@ function tp.rail_and_can_be_bent(originpos, conn)
 	if not nnpref then return false end
 	local tr=tp.tracks[nnpref]
 	if not tr then return false end
+	if not tr.modify[node.name] then 
+		--we actually can use this rail, but only if it already points to the desired direction.
+		local bconn=(conn+8)%16
+		if advtrains.is_track_and_drives_on(node.name, advtrains.all_tracktypes) then
+			local cconn1, cconn2=advtrains.get_track_connections(node.name, node.param2)
+			return cconn1==bconn or cconn2==bconn
+		end
+	end
 	--rail at other end?
 	local adj1, adj2=tp.find_already_connected(pos)
 	if adj1 and adj2 then
@@ -147,9 +165,17 @@ function tp.placetrack(pos, nnpref, placer, itemstack, pointed_thing, yaw)
 	--1. find all rails that are likely to be connected
 	local tr=tp.tracks[nnpref]
 	local p_rails={}
+	local p_railpos={}
 	for i=0,15 do
 		if tp.rail_and_can_be_bent(pos, i, nnpref) then
 			p_rails[#p_rails+1]=i
+			p_railpos[i] = pos
+		else
+			local upos = {x=pos.x, y=pos.y-1, z=pos.z}
+			if tp.rail_and_can_be_bent(upos, i, nnpref) then
+				p_rails[#p_rails+1]=i
+				p_railpos[i] = upos
+			end
 		end
 	end
 	
@@ -160,8 +186,8 @@ function tp.placetrack(pos, nnpref, placer, itemstack, pointed_thing, yaw)
 			for k2, conn2 in ipairs(p_rails) do
 				if k1~=k2 then
 					if (tr.double_conn[conn1.."_"..conn2]) then
-						tp.bend_rail(pos, conn1, nnpref)
-						tp.bend_rail(pos, conn2, nnpref)
+						tp.bend_rail(p_railpos[conn1], conn1, nnpref)
+						tp.bend_rail(p_railpos[conn2], conn2, nnpref)
 						advtrains.ndb.swap_node(pos, tr.double_conn[conn1.."_"..conn2])
 						local nname=tr.double_conn[conn1.."_"..conn2].name
 						if minetest.registered_nodes[nname] and minetest.registered_nodes[nname].after_place_node then
@@ -184,7 +210,7 @@ function tp.placetrack(pos, nnpref, placer, itemstack, pointed_thing, yaw)
 			end
 			if sconn1[p_rail] then
 				local using = sconn1[p_rail]
-				tp.bend_rail(pos, p_rail, nnpref)
+				tp.bend_rail(p_railpos[p_rail], p_rail, nnpref)
 				advtrains.ndb.swap_node(pos, using)
 				local nname=using.name
 				if minetest.registered_nodes[nname] and minetest.registered_nodes[nname].after_place_node then
@@ -194,7 +220,7 @@ function tp.placetrack(pos, nnpref, placer, itemstack, pointed_thing, yaw)
 			end
 			if sconn2[p_rail] then
 				local using = sconn2[p_rail]
-				tp.bend_rail(pos, p_rail, nnpref)
+				tp.bend_rail(p_railpos[p_rail], p_rail, nnpref)
 				advtrains.ndb.swap_node(pos, using)
 				local nname=using.name
 				if minetest.registered_nodes[nname] and minetest.registered_nodes[nname].after_place_node then