[Discussion] [API] advtrains.get_wagon_at_pos(pos) v1 SUPERSEDED

Y. Wang: 1
 Add API to get wagons at a specific position

 2 files changed, 31 insertions(+), 0 deletions(-)

Hi again,

Just noticed you added a patch here an hour ago... Which means we were
working in parallel.

My remark still holds though, and I believe my implementation is
correct.

Y. Wang <yw05@forksworld.de>

6 months ago

Agreed. I put together that patch based on reading some existing code 
and my (limited) knowledge of the path system.

Anyway, I wrote that function as an auxiliary function for 
occ.get_wagon_at(pos) since Maverick2797 wanted to get the wagon at a 
speicific position; the idea is to use occ.get_trains_at(pos) and remap 
the returned table to wagons (instead of trains).

A function to return a _single_ wagon at the position should IMO not be 
necessary as a occ.get_trains_at(pos)-like function would allow you to 
get it using next(occ.get_wagons_at(pos)).

Regards,
orwell

Hi,

yes, generally this is the right way to do. However you need to be
careful because the index does not necessarily match the real position
(an index of 1 can be a distance greater than 1)

Since I have some time today, I added such a function in 283efc4. You
should be able to use it right away.

Regards,
orwell

[PATCH] Add API to get wagons at a specific position Export this patch

---
 advtrains/occupation.lua | 14 ++++++++++++++
 advtrains/trainlogic.lua | 17 +++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/advtrains/occupation.lua b/advtrains/occupation.lua
index db39991..18e3f2b 100644
--- a/advtrains/occupation.lua
+++ b/advtrains/occupation.lua
@@ -186,6 +186,20 @@ function o.get_trains_at(ppos)
 	return r
 end
 
+-- Gets a mapping of wagon id's to offsets of wagons that stand or drive over;
+-- the offset is relative to the center of the wagon
+-- returns (table with wagon_id->offset)
+function o.get_wagons_at(pos)
+	local r = {}
+	for id, idx in pairs(o.get_trains_at(pos)) do
+		local w, offset = advtrains.get_wagon_at_index(id, idx)
+		if w then
+			r[w.id] = offset
+		end
+	end
+	return r
+end
+
 -- Gets a mapping of train id's to indexes of trains that have a path
 -- generated over this node
 -- returns (table with train_id->index)
diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
index 288e224..186a7ff 100644
--- a/advtrains/trainlogic.lua
+++ b/advtrains/trainlogic.lua
@@ -1238,6 +1238,23 @@ function advtrains.get_train_at_pos(pos)
 	end
 end
 
+function advtrains.get_wagon_at_index(train, index)
+	if train == nil then
+		return
+	elseif type(train) ~= "table" then
+		return advtrains.get_wagon_at_index(advtrains.trains[train], index)
+	end
+	local offset = train.index - index
+	local p0, p1 = 0, 0
+	for _, wid in ipairs(train.trainparts) do
+		local wagon = advtrains.wagons[wid]
+		local wp = advtrains.wagon_prototypes[wagon.type] or advtrains.wagon_prototypes["advtrains:wagon_placeholder"]
+		p0, p1 = p1, p1+2*wp.wagon_span
+		if offset <= p1 then
+			return wagon, wagon.pos_in_train - offset
+		end
+	end
+end
 
 -- ehm... I never adapted this function to the new path system ?!
 function advtrains.invalidate_all_paths(pos)
-- 
2.40.1