On-Track Collision system: Fix train teleportation when using split_at_index() from LuaATC

Issue was that train thought it would collide with the newly added back portion although it was already long past this train. Added additional check that current train index is not further than the collision point.

2 files changed, 14 insertions, 2 deletions

diff --git a/advtrains/couple.lua b/advtrains/couple.lua
index c421f61..3e6c432 100644
--- a/advtrains/couple.lua
+++ b/advtrains/couple.lua
@@ -252,6 +252,8 @@ function advtrains.couple_trains(init_train, invert_init_train, stat_train, stat
 	init_train.index = advtrains.path_get_index_by_offset(init_train, init_train.index, stat_trainlen)
 
 	advtrains.update_trainpart_properties(init_train.id)
+	advtrains.update_train_start_and_end(init_train)
+
 	advtrains.couple_invalidate(init_train)
 	return true
 end
diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
index 4650f9e..e7f2fd4 100644
--- a/advtrains/trainlogic.lua
+++ b/advtrains/trainlogic.lua
@@ -251,6 +251,11 @@ local callbacks_update, run_callbacks_update = mkcallback("update")
 local callbacks_create, run_callbacks_create = mkcallback("create")
 local callbacks_remove, run_callbacks_remove = mkcallback("remove")
 
+-- required to call from couple.lua
+function advtrains.update_train_start_and_end(train)
+	recalc_end_index(train)
+	run_callbacks_update(train.id, train)
+end
 
 -- train_ensure_init: responsible for creating a state that we can work on, after one of the following events has happened:
 -- - the train's path got cleared
@@ -643,7 +648,8 @@ function advtrains.train_step_b(id, train, dtime)
 				if target_is_inside then
 					local our_index = advtrains.path_project(otrn, ref_index, id)
 					--atdebug("Backprojected our_index",our_index)
-					if our_index and our_index <= new_index_curr_tv then
+					if our_index and our_index <= new_index_curr_tv
+							and our_index >= train.index then --FIX: If train was already past the collision point in the previous step, there is no collision! Fixes bug with split_at_index
 						-- ON_TRACK COLLISION IS HAPPENING
 						-- the actual collision is handled in train_step_c, so set appropriate signal variables
 						train.ontrack_collision_info = {
@@ -1113,6 +1119,7 @@ end
 
 function advtrains.split_train_at_index(train, index)
 	-- this function splits a train at index, creating a new train from the back part of the train.
+	--atdebug("split_train_at_index invoked on",train.id,"index",index)
 
 	local train_id=train.id
 	if index > #train.trainparts then
@@ -1135,6 +1142,7 @@ function advtrains.split_train_at_index(train, index)
 
 	local p_index=advtrains.path_get_index_by_offset(train, train.index, - data.pos_in_train + wagon.wagon_span)
 	local pos, connid, frac = advtrains.path_getrestore(train, p_index)
+	--atdebug("new train position p_index",p_index,"pos",pos,"connid",connid,"frac",frac)
 	local tp = {}
 	for k,v in ipairs(train.trainparts) do
 		if k >= index then
@@ -1144,12 +1152,14 @@ function advtrains.split_train_at_index(train, index)
 	end
 	advtrains.update_trainpart_properties(train_id)
 	recalc_end_index(train)
+	--atdebug("old train index",train.index,"end_index",train.end_index)
 	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]
-	
+	--atdebug("new train created with ID",newtrain_id,"index",newtrain.index,"end_index",newtrain.end_index)
+
 	newtrain.velocity=train.velocity
 	-- copy various properties from the old to the new train
 	newtrain.door_open = train.door_open