From 46c4447da089146c662f217bf3269d78d4c462c2 Mon Sep 17 00:00:00 2001
From: orwell96 <orwell@bleipb.de>
Date: Mon, 18 Dec 2017 21:44:36 +0100
Subject: Rewrite rail connection system... ...to support an arbitrary number
 of connections for rails, which leads to these new features: - switches now
 get recognized by the trackworker correctly - ability to add real rail
 crosses During this, I also rewrote the rail registering system and the
 conway function (important part of path prediction) Note, developers: the
 track preset format changed, you might need to rewrite them according to the
 presets in tracks.lua if you wrote your own (possibly breaks advcarts)

---
 advtrains/path.lua | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 advtrains/path.lua

(limited to 'advtrains/path.lua')

diff --git a/advtrains/path.lua b/advtrains/path.lua
new file mode 100644
index 0000000..506f27f
--- /dev/null
+++ b/advtrains/path.lua
@@ -0,0 +1,82 @@
+-- path.lua
+-- Functions for pathpredicting, put in a separate file. 
+
+function advtrains.conway(midreal, prev, drives_on)--in order prev,mid,return
+	local mid=advtrains.round_vector_floor_y(midreal)
+	
+	local midnode_ok, midconns=advtrains.get_rail_info_at(mid, drives_on)
+	if not midnode_ok then
+		return nil 
+	end
+	local pconnid
+	for connid, conn in ipairs(midconns) do
+		local tps = advtrains.dirCoordSet(mid, conn.c)
+		if tps.x==prev.x and tps.z==prev.z then
+			pconnid=connid
+		end
+	end
+	local nconnid = advtrains.get_matching_conn(pconnid, #midconns)
+	
+	local next, next_connid, _, nextrailheight = advtrains.get_adjacent_rail(mid, midconns, nconnid, drives_on)
+	if not next then
+		return nil
+	end
+	return vector.add(advtrains.round_vector_floor_y(next), {x=0, y=nextrailheight, z=0}), midconns[nconnid].c
+end
+
+--about regular: Used by 1. to ensure path gets generated far enough, since end index is not known at this time.
+function advtrains.pathpredict(id, train, regular)
+	--TODO duplicate code under 5b.
+	local path_pregen=10
+	
+	local gen_front= path_pregen
+	local gen_back= - train.trainlen - path_pregen
+	if regular then
+		gen_front=math.max(train.index, train.detector_old_index) + path_pregen
+		gen_back=math.min(train.end_index, train.detector_old_end_index) - path_pregen
+	end
+	
+	local maxn=train.path_extent_max or 0
+	while maxn < gen_front do--pregenerate
+		local conway
+		if train.max_index_on_track == maxn then
+			--atprint("maxn conway for ",maxn,train.path[maxn],maxn-1,train.path[maxn-1])
+			conway=advtrains.conway(train.path[maxn], train.path[maxn-1], train.drives_on)
+		end
+		if conway then
+			train.path[maxn+1]=conway
+			train.max_index_on_track=maxn+1
+		else
+			--do as if nothing has happened and preceed with path
+			--but do not update max_index_on_track
+			atprint("over-generating path max to index ",(maxn+1)," (position ",train.path[maxn]," )")
+			train.path[maxn+1]=vector.add(train.path[maxn], vector.subtract(train.path[maxn], train.path[maxn-1]))
+		end
+		train.path_dist[maxn]=vector.distance(train.path[maxn+1], train.path[maxn])
+		maxn=maxn+1
+	end
+	train.path_extent_max=maxn
+	
+	local minn=train.path_extent_min or -1
+	while minn > gen_back do
+		local conway
+		if train.min_index_on_track == minn then
+			--atprint("minn conway for ",minn,train.path[minn],minn+1,train.path[minn+1])
+			conway=advtrains.conway(train.path[minn], train.path[minn+1], train.drives_on)
+		end
+		if conway then
+			train.path[minn-1]=conway
+			train.min_index_on_track=minn-1
+		else
+			--do as if nothing has happened and preceed with path
+			--but do not update min_index_on_track
+			atprint("over-generating path min to index ",(minn-1)," (position ",train.path[minn]," )")
+			train.path[minn-1]=vector.add(train.path[minn], vector.subtract(train.path[minn], train.path[minn+1]))
+		end
+		train.path_dist[minn-1]=vector.distance(train.path[minn], train.path[minn-1])
+		minn=minn-1
+	end
+	train.path_extent_min=minn
+	if not train.min_index_on_track then train.min_index_on_track=-1 end
+	if not train.max_index_on_track then train.max_index_on_track=0 end
+end
-- 
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