fix: some propagation bugs

core/include/detray/builders/volume_builder.hpp

@@ -107,6 +107,10 @@ class volume_builder : public volume_builder_interface<detector_t> {
 
         DETRAY_VERBOSE_HOST("Build surfaces...");
 
+        assert(!m_surfaces.empty());
+        assert(!m_transforms.empty());
+        assert(!m_masks.all_empty());
+
         // Prepare volume data
         m_volume.set_index(static_cast<dindex>(det.volumes().size()));
 

core/include/detray/geometry/detail/volume_kernels.hpp

@@ -17,7 +17,7 @@
 
 namespace detray::detail {
 
-/// A functor to retrieve the material parameters
+/// A functor to retrieve the volume material parameters at a given position
 struct get_material_params {
     template <typename mat_group_t, typename index_t, concepts::point point_t>
     DETRAY_HOST_DEVICE inline auto operator()(const mat_group_t &mat_group,
@@ -43,9 +43,10 @@ struct get_material_params {
     }
 };
 
-/// A functor to access the surfaces of a volume
+/// A functor to access all surfaces registered in an acceleration structure
+/// @tparam functor_t functor that performs a task per surface
 template <typename functor_t>
-struct surface_getter {
+struct apply_to_surfaces {
 
     /// Call operator that forwards the neighborhood search call in a volume
     /// to a surface finder data structure
@@ -54,16 +55,18 @@ struct surface_getter {
                                               const accel_index_t index,
                                               Args &&...args) const {
 
-        // Run over the surfaces in a single acceleration data structure
+        // Iterate through the surface neighbouhood of the track
         for (const auto &sf : group[index].all()) {
             functor_t{}(sf, std::forward<Args>(args)...);
         }
     }
 };
 
 /// A functor to find surfaces in the neighborhood of a track position
+/// @tparam functor_t functor that performs a task per surface in the
+///                   neighbourhood (e.g. intersection)
 template <typename functor_t>
-struct neighborhood_getter {
+struct apply_to_neighbourhood {
 
     /// Call operator that forwards the neighborhood search call in a volume
     /// to a surface finder data structure
@@ -77,22 +80,14 @@ struct neighborhood_getter {
         const typename detector_t::geometry_context &ctx,
         Args &&...args) const {
 
+        // Get the acceleration structure for the volume
         decltype(auto) accel = group[index];
 
-        // Run over the surfaces in a single acceleration data structure
+        // Iterate through the surface neighbouhood of the track
         for (const auto &sf : accel.search(det, volume, track, cfg, ctx)) {
             functor_t{}(sf, std::forward<Args>(args)...);
         }
     }
 };
 
-/// Query the maximal number of candidates from the acceleration
-struct n_candidates_getter {
-    template <typename accel_group_t, typename accel_index_t>
-    DETRAY_HOST_DEVICE inline auto operator()(const accel_group_t &group,
-                                              const accel_index_t index) const {
-        return group[index].n_max_candidates();
-    }
-};
-
 }  // namespace detray::detail

core/include/detray/geometry/surface.hpp

@@ -148,12 +148,7 @@ class surface {
 
     /// @returns true if the surface carries material.
     DETRAY_HOST_DEVICE
-    constexpr auto has_material() const -> bool {
-        return m_desc.material().id() !=
-                   static_cast<typename descr_t::material_link::id_type>(
-                       detector_t::materials::id::e_none) &&
-               !m_desc.material().is_invalid();
-    }
+    constexpr bool has_material() const { return m_desc.has_material(); }
 
     /// @returns the mask volume link
     DETRAY_HOST_DEVICE

core/include/detray/geometry/surface_descriptor.hpp

@@ -149,6 +149,13 @@ class surface_descriptor {
         return m_material;
     }
 
+    /// @returns true if the surface descriptor has a valid material link
+    DETRAY_HOST_DEVICE
+    constexpr auto has_material() const -> bool {
+        return (m_material.id() != material_link::id_type::e_none) &&
+               !m_material.is_invalid();
+    }
+
     /// @returns true if the surface is a senstive detector module.
     DETRAY_HOST_DEVICE
     constexpr auto is_sensitive() const -> bool {

core/include/detray/geometry/tracking_volume.hpp

@@ -113,11 +113,7 @@ class tracking_volume {
 
     /// @returns true if the volume carries material.
     DETRAY_HOST_DEVICE
-    constexpr auto has_material() const -> bool {
-        return m_desc.material().id() !=
-               static_cast<typename descr_t::material_link::id_type>(
-                   detector_t::materials::id::e_none);
-    }
+    constexpr bool has_material() const { return m_desc.has_material(); }
 
     /// @returns an iterator pair for the requested type of surfaces.
     template <surface_id sf_type = surface_id::e_all>
@@ -131,11 +127,9 @@ class tracking_volume {
         }
     }
 
-    /// @returns an iterator pair for the requested type of surfaces.
+    /// @returns an iterator pair for the volume portals.
     DETRAY_HOST_DEVICE constexpr decltype(auto) portals() const {
-        return detray::ranges::subrange{
-            m_detector.surfaces(),
-            m_desc.template sf_link<surface_id::e_portal>()};
+        return surfaces<surface_id::e_portal>();
     }
 
     /// @returns the total number of portal surfaces contained in the volume
@@ -171,15 +165,15 @@ class tracking_volume {
     /// @tparam Args      types of additional arguments to the functor
     template <typename functor_t, typename... Args>
     DETRAY_HOST_DEVICE constexpr void visit_surfaces(Args &&...args) const {
-        visit_surfaces_impl<detail::surface_getter<functor_t>>(
+        visit_surfaces_impl<detail::apply_to_surfaces<functor_t>>(
             std::forward<Args>(args)...);
     }
 
     /// Apply a functor to a neighborhood of surfaces around a track position
     /// in the volume.
     ///
-    /// @tparam functor_t the prescription to be applied to the surfaces (
-    ///                   customization point for the navigation)
+    /// @tparam functor_t the prescription to be applied to the surfaces
+    ///                   (customization point for the navigation)
     /// @tparam track_t   the track around which to build up the neighborhood
     /// @tparam Args      types of additional arguments to the functor
     template <typename functor_t, typename track_t, typename config_t,
@@ -188,7 +182,7 @@ class tracking_volume {
                                                          const config_t &cfg,
                                                          const context_t &ctx,
                                                          Args &&...args) const {
-        visit_surfaces_impl<detail::neighborhood_getter<functor_t>>(
+        visit_surfaces_impl<detail::apply_to_neighbourhood<functor_t>>(
             m_detector, m_desc, track, cfg, ctx, std::forward<Args>(args)...);
     }
 
@@ -331,7 +325,7 @@ class tracking_volume {
     private:
     /// Apply a functor to all acceleration structures of this volume.
     ///
-    /// @tparam functor_t the prescription to be applied to the acc structure
+    /// @tparam functor_t the prescription to be applied to the acc. structures
     /// @tparam Args      types of additional arguments to the functor
     template <typename functor_t, typename... Args>
     DETRAY_HOST_DEVICE constexpr void visit_surfaces_impl(
@@ -344,8 +338,7 @@ class tracking_volume {
             if (const auto &link{m_desc.accel_link(
                     static_cast<typename descr_t::object_id>(i))};
                 !link.is_invalid()) {
-                // Run over the surfaces in a single acceleration data structure
-                // and apply the functor to the resulting neighborhood
+                // Get the acc. data structure and apply the functor to it
                 m_detector.accelerator_store().template visit<functor_t>(
                     link, std::forward<Args>(args)...);
             }

core/include/detray/geometry/volume_descriptor.hpp

@@ -235,6 +235,13 @@ class volume_descriptor {
                       static_cast<typename material_link::index_type>(mat_idx)};
     }
 
+    /// @returns true if the volume descriptor has a valid material link
+    DETRAY_HOST_DEVICE
+    constexpr auto has_material() const -> bool {
+        return (m_mat_link.id() != material_link::id_type::e_none) &&
+               !m_mat_link.is_invalid();
+    }
+
     /// @returns link to all acceleration data structures - const access
     DETRAY_HOST_DEVICE constexpr auto accel_link() const
         -> const accel_link_type& {

core/include/detray/navigation/policies.hpp

@@ -11,6 +11,7 @@
 #include "detray/definitions/algebra.hpp"
 #include "detray/definitions/detail/qualifiers.hpp"
 #include "detray/definitions/math.hpp"
+#include "detray/definitions/units.hpp"
 #include "detray/propagator/base_actor.hpp"
 
 // system includes
@@ -114,7 +115,7 @@ struct stepper_rk_policy : actor {
         auto &navigation = propagation._navigation;
 
         // In case of an overlap, have navigator re-evaluate the next candidate
-        if (math::fabs(navigation()) <= 1e-5f) {
+        if (math::fabs(navigation()) <= 1.f * unit<float>::um) {
             navigation.set_high_trust();
             return;
         }

core/include/detray/propagator/actors/pointwise_material_interactor.hpp

@@ -230,7 +230,7 @@ struct pointwise_material_interactor : actor {
         const scalar_type next_qop{(q != 0.f) ? q / next_p : 1.f / next_p};
         vector.set_qop((next_p == 0.f) ? inv : next_qop);
 
-        DETRAY_DEBUG_HOST_DEVICE("-> new abs. momentum: %f", next_qop);
+        DETRAY_DEBUG_HOST_DEVICE("-> new abs. momentum: %f", next_p);
 
         DETRAY_DEBUG_HOST_DEVICE("-> Update qop: before: %f, after: %f", q / p,
                                  vector.qop());

core/include/detray/propagator/detail/noise_estimation.hpp

@@ -73,9 +73,10 @@ DETRAY_HOST_DEVICE constexpr void estimate_external_mask_tolerance(
                                math::cos(theta_err)};
 
     // Guess the portal envelope distance if there is no next target
+    constexpr auto max_tol{5.f * unit<scalar_t>::mm};
     const scalar_t path{
         navigation.is_exhausted()
-            ? 5.f * unit<scalar_t>::mm
+            ? max_tol
             : math::fabs(std::as_const(navigation).target().path())};
 
     displ = path * (displ - stepping().dir());
@@ -97,7 +98,6 @@ DETRAY_HOST_DEVICE constexpr void estimate_external_mask_tolerance(
         vector::dot(displ, displ) + accumulated_noise * accumulated_noise));
 
     // Clip to 5mm if the covariances are very large
-    constexpr auto max_tol{5.f * unit<scalar_t>::mm};
     navigation.set_external_tol(navigation.external_tol() > max_tol
                                     ? max_tol
                                     : navigation.external_tol());