feat: allow custom precision for volume grid building

Core/include/Acts/Detector/detail/CylindricalDetectorHelper.hpp

@@ -172,12 +172,14 @@ DetectorComponent::PortalContainer wrapInZR(
 ///
 /// @param gctx the geometry context of the call
 /// @param volumes the volumes at input
+/// @param precision the precision to be used for (optionally)
 /// @param logLevel is the screen logging level
 ///
 /// @return extracted boundary values
 template <typename volume_container_t>
 std::array<std::vector<ActsScalar>, 3u> rzphiBoundaries(
     const GeometryContext& gctx, const volume_container_t& volumes,
+    double precision = 0.,
     Acts::Logging::Level logLevel = Acts::Logging::INFO) {
   // The local logger
   ACTS_LOCAL_LOGGER(getDefaultLogger("CylindricalDetectorHelper", logLevel));
@@ -187,6 +189,13 @@ std::array<std::vector<ActsScalar>, 3u> rzphiBoundaries(
 
   // The return boundaries
   std::array<std::set<ActsScalar>, 3u> uniqueBoundaries;
+  auto insertWithPrecision = [&](std::size_t is, ActsScalar value) -> void {
+    if (precision == 0.) {
+      uniqueBoundaries[is].insert(value);
+      return;
+    }
+    uniqueBoundaries[is].insert(std::round(value / precision) * precision);
+  };
 
   // Loop over the volumes and collect boundaries
   for (const auto& v : volumes) {
@@ -207,12 +216,12 @@ std::array<std::vector<ActsScalar>, 3u> rzphiBoundaries(
       ActsScalar phiMin = phiCenter - phiSector;
       ActsScalar phiMax = phiCenter + phiSector;
       // Fill the sets
-      uniqueBoundaries[0].insert(rMin);
-      uniqueBoundaries[0].insert(rMax);
-      uniqueBoundaries[1].insert(zMin);
-      uniqueBoundaries[1].insert(zMax);
-      uniqueBoundaries[2].insert(phiMin);
-      uniqueBoundaries[2].insert(phiMax);
+      insertWithPrecision(0u, rMin);
+      insertWithPrecision(0u, rMax);
+      insertWithPrecision(1u, zMin);
+      insertWithPrecision(1u, zMax);
+      insertWithPrecision(2u, phiMin);
+      insertWithPrecision(2u, phiMax);
     }
   }
 

Tests/UnitTests/Core/Detector/CylindricalDetectorHelperTests.cpp

@@ -646,7 +646,8 @@ BOOST_AUTO_TEST_CASE(RZPhiBoundaries) {
   std::vector<std::shared_ptr<DetectorVolume>> volumes = {
       innerV, middleLV, middleDV, middleUV, middleRV, outerV};
 
-  auto boundaries = rzphiBoundaries(tContext, volumes, Acts::Logging::VERBOSE);
+  auto boundaries =
+      rzphiBoundaries(tContext, volumes, 0., Acts::Logging::VERBOSE);
   BOOST_CHECK(boundaries.size() == 3u);
   // Check the r boundaries
   std::vector<ActsScalar> rBoundaries = {0., 20., 40., 60., 120.};
@@ -657,4 +658,26 @@ BOOST_AUTO_TEST_CASE(RZPhiBoundaries) {
   BOOST_CHECK(boundaries[2u].size() == 2u);
 }
 
+BOOST_AUTO_TEST_CASE(RZPhiBoundariesWithTolerance) {
+  auto innerB = std::make_unique<CylinderVolumeBounds>(0., 20., 100);
+  auto innerV = DetectorVolumeFactory::construct(
+      portalGenerator, tContext, "Inner", Transform3::Identity(),
+      std::move(innerB), tryAllPortals());
+
+  auto outerB = std::make_unique<CylinderVolumeBounds>(20.001, 100., 100);
+  auto outerV = DetectorVolumeFactory::construct(
+      portalGenerator, tContext, "Inner", Transform3::Identity(),
+      std::move(outerB), tryAllPortals());
+
+  std::vector<std::shared_ptr<DetectorVolume>> volumes = {innerV, outerV};
+
+  auto boundariesWoTol =
+      rzphiBoundaries(tContext, volumes, 0., Acts::Logging::VERBOSE);
+  BOOST_CHECK_EQUAL(boundariesWoTol[0u].size(), 4u);
+
+  auto boundariesWTol =
+      rzphiBoundaries(tContext, volumes, 0.01, Acts::Logging::VERBOSE);
+  BOOST_CHECK_EQUAL(boundariesWTol[0u].size(), 3u);
+}
+
 BOOST_AUTO_TEST_SUITE_END()