From 662b34fbc7f623c8e55b4729317d25dbf45205c8 Mon Sep 17 00:00:00 2001
From: Andreas Stefl <stefl.andreas@gmail.com>
Date: Thu, 28 Mar 2024 20:43:48 +0100
Subject: [PATCH] twoWay=true; extrapolate second

---
 .../TrackFinding/TrackFindingAlgorithm.hpp    |  2 +-
 .../src/TrackFindingAlgorithm.cpp             | 28 +++++++++++++++----
 .../python/acts/examples/reconstruction.py    |  2 +-
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/Examples/Algorithms/TrackFinding/include/ActsExamples/TrackFinding/TrackFindingAlgorithm.hpp b/Examples/Algorithms/TrackFinding/include/ActsExamples/TrackFinding/TrackFindingAlgorithm.hpp
index 6091bb9a412..4c6ad13c91a 100644
--- a/Examples/Algorithms/TrackFinding/include/ActsExamples/TrackFinding/TrackFindingAlgorithm.hpp
+++ b/Examples/Algorithms/TrackFinding/include/ActsExamples/TrackFinding/TrackFindingAlgorithm.hpp
@@ -112,7 +112,7 @@ class TrackFindingAlgorithm final : public IAlgorithm {
     Acts::TrackExtrapolationStrategy extrapolationStrategy =
         Acts::TrackExtrapolationStrategy::firstOrLast;
     /// Run finding in two directions
-    bool twoWay = false;
+    bool twoWay = true;
   };
 
   /// Constructor of the track finding algorithm
diff --git a/Examples/Algorithms/TrackFinding/src/TrackFindingAlgorithm.cpp b/Examples/Algorithms/TrackFinding/src/TrackFindingAlgorithm.cpp
index ace9bd94405..ed1396377d5 100644
--- a/Examples/Algorithms/TrackFinding/src/TrackFindingAlgorithm.cpp
+++ b/Examples/Algorithms/TrackFinding/src/TrackFindingAlgorithm.cpp
@@ -246,6 +246,22 @@ ActsExamples::ProcessCode ActsExamples::TrackFindingAlgorithm::execute(
 
               Acts::calculateTrackQuantities(secondTrack);
 
+              // TODO this extrapolation should not be necessary as the CKF will
+              // target this surface anyway and could communicate the parameters
+              auto secondExtrapolationResult =
+                  Acts::extrapolateTrackToReferenceSurface(
+                      secondTrack, *pSurface, extrapolator,
+                      extrapolationOptions, m_cfg.extrapolationStrategy,
+                      logger());
+              if (!secondExtrapolationResult.ok()) {
+                m_nFailedExtrapolation++;
+                ACTS_ERROR("Second extrapolation for seed "
+                           << iSeed << " and track " << firstTrack.index()
+                           << " failed with error "
+                           << secondExtrapolationResult.error());
+                continue;
+              }
+
               if (!m_trackSelector.has_value() ||
                   m_trackSelector->isValidTrack(secondTrack)) {
                 auto destProxy = tracks.getTrack(tracks.addTrack());
@@ -259,14 +275,16 @@ ActsExamples::ProcessCode ActsExamples::TrackFindingAlgorithm::execute(
       }
 
       if (nSecond == 0) {
-        auto extrapolationResult = Acts::extrapolateTrackToReferenceSurface(
-            firstTrack, *pSurface, extrapolator, extrapolationOptions,
-            m_cfg.extrapolationStrategy, logger());
-        if (!extrapolationResult.ok()) {
+        auto firstExtrapolationResult =
+            Acts::extrapolateTrackToReferenceSurface(
+                firstTrack, *pSurface, extrapolator, extrapolationOptions,
+                m_cfg.extrapolationStrategy, logger());
+        if (!firstExtrapolationResult.ok()) {
           m_nFailedExtrapolation++;
           ACTS_ERROR("Extrapolation for seed "
                      << iSeed << " and track " << firstTrack.index()
-                     << " failed with error " << extrapolationResult.error());
+                     << " failed with error "
+                     << firstExtrapolationResult.error());
           continue;
         }
 
diff --git a/Examples/Python/python/acts/examples/reconstruction.py b/Examples/Python/python/acts/examples/reconstruction.py
index 243a8d16f9f..52f8947c246 100644
--- a/Examples/Python/python/acts/examples/reconstruction.py
+++ b/Examples/Python/python/acts/examples/reconstruction.py
@@ -1164,7 +1164,7 @@ def addCKFTracks(
         Union[TrackSelectorConfig, List[TrackSelectorConfig]]
     ] = None,
     ckfConfig: CkfConfig = CkfConfig(),
-    twoWay: bool = False,
+    twoWay: bool = True,
     outputDirCsv: Optional[Union[Path, str]] = None,
     outputDirRoot: Optional[Union[Path, str]] = None,
     writeTrajectories: bool = True,