From 00d83fe3f414135b8c1c8f79bf03d77f2bd83f73 Mon Sep 17 00:00:00 2001
From: Wouter Deconinck <wdconinc@gmail.com>
Date: Fri, 19 Jan 2024 18:42:15 -0600
Subject: [PATCH] fix: use qOverP to get the charge of TrackParameters (#18)

After https://github.com/eic/EDM4eic/pull/58, there is no more `charge` field in edm4eic::TrackParameters, so we have to get this from `qOverP`, but this is backwards compatible.
---
 truth/src/ParticlesWithTruthPID.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/truth/src/ParticlesWithTruthPID.cpp b/truth/src/ParticlesWithTruthPID.cpp
index b0f604a..cce5f67 100644
--- a/truth/src/ParticlesWithTruthPID.cpp
+++ b/truth/src/ParticlesWithTruthPID.cpp
@@ -29,7 +29,7 @@ void ParticlesWithTruthPID::process(const ParticlesWithTruthPID::Input& input,
   for (const auto& trk : tracks) {
     const auto mom =
         edm4hep::utils::sphericalToVector(1.0 / std::abs(trk.getQOverP()), trk.getTheta(), trk.getPhi());
-    const auto charge_rec = trk.getCharge();
+    const auto charge_rec = std::copysign(1., trk.getQOverP());
     // utility variables for matching
     int best_match    = -1;
     double best_delta = std::numeric_limits<double>::max();