fix: Fixing navigation failures on volume boundaries edges (#1722)

Implements a way to hit boundaries when this is the only possible option. Closes #1720
acts-project · Dec 13, 2022 · 4e60261 · 4e60261
1 parent bbf2bf4
commit 4e60261
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diff --git a/Core/include/Acts/Propagator/Navigator.hpp b/Core/include/Acts/Propagator/Navigator.hpp
@@ -68,6 +68,9 @@ struct NavigationOptions {
   /// @todo could be dynamic in the future (pT dependent)
   double overstepLimit = -1 * UnitConstants::um;
 
+  /// Force intersection with boundaries
+  bool forceIntersectBoundaries = false;
+
   /// Constructor
   ///
   /// @param ndir Navigation direction prescription
@@ -216,6 +219,8 @@ class Navigator {
     bool navigationBreak = false;
     // The navigation stage (@todo: integrate break, target)
     Stage navigationStage = Stage::undefined;
+    /// Force intersection with boundaries
+    bool forceIntersectBoundaries = false;
 
     /// Reset state
     ///
@@ -932,6 +937,8 @@ class Navigator {
       navOpts.pathLimit =
           stepper.getStepSize(state.stepping, ConstrainedStep::aborter);
       navOpts.overstepLimit = stepper.overstepLimit(state.stepping);
+      navOpts.forceIntersectBoundaries =
+          state.navigation.forceIntersectBoundaries;
 
       // Exclude the current surface in case it's a boundary
       navOpts.startObject = state.navigation.currentSurface;
@@ -1002,7 +1009,10 @@ class Navigator {
     // We have to leave the volume somehow, so try again
     state.navigation.navBoundaries.clear();
     ACTS_VERBOSE(volInfo(state) << "Boundary navigation lost, re-targetting.");
+    state.navigation.forceIntersectBoundaries = true;
     if (findBoundaries()) {
+      // Resetting intersection check for boundary surfaces
+      state.navigation.forceIntersectBoundaries = false;
       return true;
     }
 

diff --git a/Core/src/Geometry/TrackingVolume.cpp b/Core/src/Geometry/TrackingVolume.cpp
@@ -484,6 +484,27 @@ Acts::TrackingVolume::compatibleBoundaries(
       return BoundaryIntersection();
     }
 
+    if (options.forceIntersectBoundaries and
+        sIntersection.intersection.pathLength * options.navDir > 0) {
+      const bool coCriterion =
+          std::abs(sIntersection.intersection.pathLength) < std::abs(oLimit);
+      ACTS_VERBOSE("Forcing intersection with surface "
+                   << bSurface->surfaceRepresentation().geometryId());
+      if (coCriterion) {
+        ACTS_VERBOSE("Intersection forced successfully ");
+        ACTS_VERBOSE("- intersection path length "
+                     << std::abs(sIntersection.intersection.pathLength)
+                     << " < overstep limit " << std::abs(oLimit));
+        sIntersection.intersection.pathLength *= options.navDir;
+        return BoundaryIntersection(sIntersection.intersection, bSurface,
+                                    sIntersection.object);
+      }
+      ACTS_VERBOSE("Can't force intersection: ");
+      ACTS_VERBOSE("- intersection path length "
+                   << std::abs(sIntersection.intersection.pathLength)
+                   << " > overstep limit " << std::abs(oLimit));
+    }
+
     ACTS_VERBOSE("Check intersection with surface "
                  << bSurface->surfaceRepresentation().geometryId());
     if (detail::checkIntersection(sIntersection.intersection, pLimit, oLimit,