rewrite collision system again

this time, it is based on nodes that trains stand on.
advtrains.detector (in tracks.lua) keeps a table with nodes that trains are standing /driving on. This will be used now for detector rails.

init.lua

@@ -4,10 +4,10 @@ advtrains={}
 
 advtrains.modpath = minetest.get_modpath("advtrains")
 
-print=function(text)
-	minetest.log("action", tostring(text) or "<non-string>")
-end
-
+--print=function(text)
+--	minetest.log("action", tostring(text) or "<non-string>")
+--end
+print = function(t) minetest.log("action", t) minetest.chat_send_all(t) end
 
 dofile(advtrains.modpath.."/helpers.lua");
 dofile(advtrains.modpath.."/debugitems.lua");

tracks.lua

@@ -237,8 +237,7 @@ function advtrains.register_tracks(tracktype, def, preset)
 	}, def.common or {})
 	--make trackplacer base def
 	advtrains.trackplacer.register_tracktype(def.nodename_prefix, preset.tpdefault)
-	advtrains.trackplacer.register_track_placer(def.nodename_prefix, def.texture_prefix, def.description)
-	
+	advtrains.trackplacer.register_track_placer(def.nodename_prefix, def.texture_prefix, def.description)			
 	for suffix, conns in pairs(preset.variant) do
 		for rotid, rotation in ipairs(preset.rotation) do
 			if not def.formats[suffix] or def.formats[suffix][rotid] then
@@ -246,6 +245,7 @@ function advtrains.register_tracks(tracktype, def, preset)
 				if preset.switch[suffix] then
 					switchfunc, mesecontbl=make_switchfunc(preset.switch[suffix]..rotation, preset.switchmc[suffix])
 				end
+				
 				minetest.register_node(def.nodename_prefix.."_"..suffix..rotation, advtrains.merge_tables(
 					common_def, 
 					make_overdef(
@@ -293,6 +293,70 @@ function advtrains.get_track_connections(name, param2)
 	return (nodedef.connect1 + 4 * noderot)%16, (nodedef.connect2  + 4 * noderot)%16, nodedef.rely1 or 0, nodedef.rely2 or 0, nodedef.railheight or 0
 end
 
+--detector code
+--holds a table with nodes on which trains are on.
+
+advtrains.detector = {}
+advtrains.detector.on_node = {}
+advtrains.detector.on_node_restore = {}
+--set if paths were invalidated before. tells trainlogic.lua to call advtrains.detector.finalize_restore()
+advtrains.detector.clean_step_before = false
+
+--when train enters a node, call this
+--The entry already being contained in advtrains.detector.on_node_restore will not trigger an on_train_enter event on the node.  (when path is reset, this is saved).
+function advtrains.detector.enter_node(pos, train_id)
+	local pts = minetest.pos_to_string(advtrains.round_vector_floor_y(pos))
+	--print("enterNode "..pts.." "..train_id)
+	if not advtrains.detector.on_node[pts] then
+		advtrains.detector.on_node[pts]=train_id
+		if advtrains.detector.on_node_restore[pts] then
+			advtrains.detector.on_node_restore[pts]=nil
+		else
+			advtrains.detector.call_enter_callback(advtrains.round_vector_floor_y(pos), train_id)
+		end
+	end
+end
+function advtrains.detector.leave_node(pos, train_id)
+	local pts = minetest.pos_to_string(advtrains.round_vector_floor_y(pos))
+	--print("leaveNode "..pts.." "..train_id)
+	if advtrains.detector.on_node[pts] then
+		advtrains.detector.call_leave_callback(advtrains.round_vector_floor_y(pos), train_id)
+		advtrains.detector.on_node[pts]=nil
+	end
+end
+--called immediately before invalidating paths
+function advtrains.detector.setup_restore()
+	--print("setup_restore")
+	advtrains.detector.on_node_restore = advtrains.detector.on_node
+	advtrains.detector.on_node = {}
+end
+--called one step after invalidating paths, when all trains have restored their path and called enter_node for their contents.
+function advtrains.detector.finalize_restore()
+	--print("finalize_restore")
+	for pts, train_id in pairs(advtrains.detector.on_node_restore) do
+		--print("called leave callback "..pts.." "..train_id)
+		advtrains.detector.call_leave_callback(minetest.string_to_pos(pts), train_id)
+	end
+	advtrains.detector.on_node_restore = {}
+end
+function advtrains.detector.call_enter_callback(pos, train_id)
+	--print("instructed to call enter calback")
+
+	local node = minetest.get_node(pos) --this spares the check if node is nil, it has a name in any case
+	local mregnode=minetest.registered_nodes[node.name]
+	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_enter then
+		mregnode.advtrains.on_train_enter(pos, train_id)
+	end 
+end
+function advtrains.detector.call_leave_callback(pos, train_id)
+	--print("instructed to call leave calback")
+
+	local node = minetest.get_node(pos) --this spares the check if node is nil, it has a name in any case
+	local mregnode=minetest.registered_nodes[node.name]
+	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_leave then
+		mregnode.advtrains.on_train_leave(pos, train_id)
+	end 
+end
 --END code, BEGIN definition
 --definition format: ([] optional)
 --[[{

trainlogic.lua

@@ -155,6 +155,12 @@ minetest.register_globalstep(function(dtime)
 	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)
@@ -204,6 +210,41 @@ function advtrains.train_step(id, train, dtime)
 		if train.tarvelocity<0 then train.tarvelocity=0 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)
+	
 	if train_moves then
 		--check for collisions by finding objects
 		--front
@@ -224,23 +265,26 @@ function advtrains.train_step(id, train, dtime)
 				end
 			end
 		end
-		--new train collisions (only search in the direction of the driving train)
-		local coll_search_radius=2
-		local coll_grace=0
+		--heh, new collision again.
+		--this time, based on NODES and the advtrains.detector.on_node table.
 		local collpos
+		local coll_grace=1
 		if train.velocity>0 then
 			collpos=advtrains.get_real_index_position(path, train.index-coll_grace)
 		elseif train.velocity<0 then
 			collpos=advtrains.get_real_index_position(path, train_end_index+coll_grace)
 		end
 		if collpos then
-			local objrefs=minetest.get_objects_inside_radius(collpos, coll_search_radius)
-			for _,v in pairs(objrefs) do
-				local le=v:get_luaentity()
-				if le and le.is_wagon and le.initialized and le.train_id~=id then
-					train.recently_collided_with_env=true
-					train.velocity=-0.5*train.velocity
-					train.tarvelocity=0
+			local rcollpos=advtrains.round_vector_floor_y(collpos)
+			for x=-1,1 do
+				for z=-1,1 do
+					local testpts=minetest.pos_to_string(vector.add(rcollpos, {x=x, y=0, z=z}))
+					if advtrains.detector.on_node[testpts] and advtrains.detector.on_node[testpts]~=id then
+						--collides
+						train.recently_collided_with_env=true
+						train.velocity=-0.5*train.velocity
+						train.tarvelocity=0
+					end
 				end
 			end
 		end
@@ -775,6 +819,10 @@ function advtrains.invalidate_all_paths()
 		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