Better code & add'l overload for THaSpectrometerDetector::CalcTrackIn…

…tercept
JeffersonLab · Jan 23, 2018 · c6ca74e · c6ca74e
1 parent b884ef8
commit c6ca74e
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Showing 2 changed files with 56 additions and 30 deletions.
diff --git a/src/THaSpectrometerDetector.C b/src/THaSpectrometerDetector.C
@@ -36,47 +36,72 @@ THaSpectrometerDetector::~THaSpectrometerDetector()
 }
 
 //_____________________________________________________________________________
-bool THaSpectrometerDetector::CalcTrackIntercept(THaTrack* theTrack,
-					 Double_t& t, Double_t& xcross,
-					 Double_t& ycross)
+Bool_t THaSpectrometerDetector::CalcTrackIntercept( THaTrack* theTrack,
+						    TVector3& icept,
+						    Double_t& pathl )
 {
-  // projects a given track on to the plane of the detector
-  // xcross and ycross are the x and y coords of this intersection
-  // t is the distance from the origin of the track to the given plane.
+  // Find intercept coordinates of given track with the plane of
+  // this detector. Results are in 'icept' and 'pathl'
   //
-  // If a hit is NOT found, then t, xcross, and ycross are unchanged.
+  // icept:  Vector to track crossing point in track coordinate system
+  // pathl:  pathlength from track origin (in the track coordinate system)
+  //         to intersection point (m). This is identical to the length
+  //         of the vector icept-t0
+
   TVector3 t0( theTrack->GetX(), theTrack->GetY(), 0.0 );
-  Double_t norm = TMath::Sqrt(1.0 + theTrack->GetTheta()*theTrack->GetTheta() +
-			      theTrack->GetPhi()*theTrack->GetPhi());
-  TVector3 t_hat( theTrack->GetTheta()/norm, theTrack->GetPhi()/norm, 1.0/norm );
+  TVector3 td( theTrack->GetTheta(), theTrack->GetPhi(), 1.0 );
+  td = td.Unit();
 
-  TVector3 v;
-  if( !IntersectPlaneWithRay( fXax, fYax, fOrigin, t0, t_hat, t, v ))
-    return false;
-  v -= fOrigin;
-  xcross = v.Dot(fXax);
-  ycross = v.Dot(fYax);
+  return IntersectPlaneWithRay( fXax, fYax, fOrigin, t0, td, pathl, icept );
+}
+
+//_____________________________________________________________________________
+Bool_t THaSpectrometerDetector::CalcTrackIntercept( THaTrack* theTrack,
+						    Double_t& pathl,
+						    Double_t& xdet,
+						    Double_t& ydet )
+{
+  // Find intercept coordinates of given track with the plane of
+  // this detector. Results are in xdet, ydet and pathl.
+  //
+  // pathl: pathlength from track origin (in the track coordinate system)
+  //        to intersection point (m). This is identical to the length
+  //        of the vector icept-track_origin
+  // xdet:  x-coordinate of intercept in detector coordinate system (m)
+  // ydet:  y-coordinate of intercept in detector coordinate system (m)
+
+  // Does not check if the intercept coordinates are actually within
+  // the active area of the detector; use IsInActiveArea(val[1],val[2])
+  // to find out.
 
+  TVector3 icept;
+  if( !CalcTrackIntercept(theTrack, icept, pathl) )
+    return false;
+  TVector3 v = TrackToDetCoord(icept);
+  xdet = v.X();
+  ydet = v.Y();
   return true;
 }
 
 //_____________________________________________________________________________
-bool THaSpectrometerDetector::CheckIntercept(THaTrack *track)
+Bool_t THaSpectrometerDetector::CheckIntercept( THaTrack *track )
 {
-  Double_t x, y, t;
-  return CalcTrackIntercept(track, t, x, y);
+  TVector3 icept;
+  Double_t t;
+  return CalcTrackIntercept(track, icept, t);
 }
 
 //_____________________________________________________________________________
-bool THaSpectrometerDetector::CalcInterceptCoords(THaTrack* track, Double_t& x, Double_t& y)
+Bool_t THaSpectrometerDetector::CalcInterceptCoords( THaTrack* track,
+						     Double_t& x, Double_t& y)
 {
   Double_t t;
   return CalcTrackIntercept(track, t, x, y);
 }
 
 //_____________________________________________________________________________
-bool THaSpectrometerDetector::CalcPathLen(THaTrack* track, Double_t& t)
+Bool_t THaSpectrometerDetector::CalcPathLen( THaTrack* track, Double_t& t )
 {
-  Double_t x, y;
-  return CalcTrackIntercept(track, t, x, y);
+  TVector3 icept;
+  return CalcTrackIntercept(track, icept, t);
 }
diff --git a/src/THaSpectrometerDetector.h b/src/THaSpectrometerDetector.h
@@ -15,6 +15,7 @@
 #include "THaDetector.h"
 
 class THaTrack;
+class TVector3;
 
 class THaSpectrometerDetector : public THaDetector {
 
@@ -24,18 +25,18 @@ class THaSpectrometerDetector : public THaDetector {
   virtual Bool_t   IsTracking() = 0;
   virtual Bool_t   IsPid()      = 0;
 
-          bool     CheckIntercept( THaTrack* track );
-          bool     CalcInterceptCoords( THaTrack* track,
+          Bool_t   CheckIntercept( THaTrack* track );
+          Bool_t   CalcInterceptCoords( THaTrack* track,
 					Double_t& x, Double_t& y );
-          bool     CalcPathLen( THaTrack* track, Double_t& t );
+          Bool_t   CalcPathLen( THaTrack* track, Double_t& t );
+          Bool_t   CalcTrackIntercept( THaTrack* track, TVector3& icept,
+				       Double_t& pathl );
+          Bool_t   CalcTrackIntercept( THaTrack* track, Double_t& pathl,
+				       Double_t& xdet, Double_t& ydet );
 
   THaSpectrometerDetector();       // for ROOT I/O only
 
 protected:
-
-          bool  CalcTrackIntercept( THaTrack* track, Double_t& t,
-				    Double_t& ycross, Double_t& xcross);
-
   //Only derived classes may construct me
   THaSpectrometerDetector( const char* name, const char* description,
 			   THaApparatus* a = NULL );