Add material grids as material maps and add the relevant types to the

detector metadata. The material maps of different shapes are tested
in a dedicated unittest.

Mapeterial maps are added to the toy detector and wire chamber via
the detector helper. The material is a silicon and aluminium mixture
that is mapped in configurable binning onto the disc and cylinder
portals.

core/include/detray/core/detector.hpp

@@ -97,7 +97,7 @@ class detector {
 
     /// Forward mask types that are present in this detector
     using material_container =
-        typename metadata::template material_store<tuple_type, vector_type>;
+        typename metadata::template material_store<tuple_type, container_t>;
     using materials = typename material_container::value_types;
     using material_link = typename material_container::single_link;
 
@@ -314,15 +314,16 @@ class detector {
     /// @returns the portals of a given volume @param v - const
     /// @note Depending on the detector type, this can also container other
     /// surfaces
-    DETRAY_HOST_DEVICE constexpr auto portals(const volume_type &v) const {
+    DETRAY_HOST_DEVICE constexpr auto portals(const volume_type &v) {
 
         // Index of the portal collection in the surface store
         const dindex pt_coll_idx{
             v.template link<geo_obj_ids::e_portal>().index()};
 
-        const auto &pt_coll =
-            _surfaces
-                .template get<sf_finders::id::e_brute_force>()[pt_coll_idx];
+        auto &bf_finder =
+            _surfaces.template get<sf_finders::id::e_brute_force>();
+
+        auto pt_coll = bf_finder[pt_coll_idx];
 
         return pt_coll.all();
     }

core/include/detray/core/detector_metadata.hpp

@@ -19,6 +19,7 @@
 #include "detray/masks/masks.hpp"
 #include "detray/masks/unbounded.hpp"
 #include "detray/masks/unmasked.hpp"
+#include "detray/materials/material_map.hpp"
 #include "detray/materials/material_rod.hpp"
 #include "detray/materials/material_slab.hpp"
 #include "detray/surface_finders/accelerator_grid.hpp"
@@ -61,9 +62,34 @@ struct default_metadata {
     using slab = material_slab<detray::scalar>;
     using rod = material_rod<detray::scalar>;
 
-    /// @TODO material grids
+    /// Material grid types (default: closed bounds, regular binning)
     /// @{
-    /// ...
+
+    // Disc material grid
+    template <typename container_t>
+    using disc_map_t =
+        material_map<ring2D<>::axes<>, detray::scalar, container_t>;
+
+    // Cylindrical material grid
+    template <typename container_t>
+    using cylinder2_map_t =
+        material_map<cylinder2D<>::axes<>, detray::scalar, container_t>;
+
+    // Rectangular material grid
+    template <typename container_t>
+    using rectangular_map_t =
+        material_map<rectangle2D<>::axes<>, detray::scalar, container_t>;
+
+    // Cuboid volume material grid
+    template <typename container_t>
+    using cuboid_map_t =
+        material_map<cuboid3D<>::axes<>, detray::scalar, container_t>;
+
+    // Cylindrical volume material grid
+    template <typename container_t>
+    using cylinder3_map_t =
+        material_map<cylinder3D::axes<>, detray::scalar, container_t>;
+
     /// @}
 
     /// surface grid types (default boundaries: closed binning)
@@ -162,19 +188,36 @@ unbounded_cell, unmasked_plane*/>;
 
     /// Give your material types a name (needs to be consecutive and has to
     /// match the types position in the mask store!)
-    /// @TODO: Add the material grid types for every surface shape
     enum class material_ids {
-        e_slab = 0,
-        e_rod = 1,
-        // ... material map types
-        e_none = 2,
+        // Material texture (grid) shapes
+        e_disc2_map = 0u,
+        e_cylinder2_map = 1u,
+        e_rectangle2_map = 2u,
+        e_trapezoid2_map = 2u,
+        e_annulus2_map = 0u,
+        e_cell_wire_map = 6u,
+        e_straw_wire_map = 6u,
+        // Volume material
+        e_cuboid3_map = 3u,
+        e_cylinder3_map = 4u,
+        // Homogeneous mapetrial
+        e_slab = 5u,
+        e_rod = 6u,
+        e_none = 7u,
     };
 
     /// How to store materials
     template <template <typename...> class tuple_t = dtuple,
-              template <typename...> class vector_t = dvector>
-    using material_store = regular_multi_store<material_ids, empty_context,
-                                               tuple_t, vector_t, slab, rod>;
+              typename container_t = host_container_types>
+    using material_store =
+        multi_store<material_ids, empty_context, tuple_t,
+                    grid_collection<disc_map_t<container_t>>,
+                    grid_collection<cylinder2_map_t<container_t>>,
+                    grid_collection<rectangular_map_t<container_t>>,
+                    grid_collection<cuboid_map_t<container_t>>,
+                    grid_collection<cylinder3_map_t<container_t>>,
+                    typename container_t::template vector_type<slab>,
+                    typename container_t::template vector_type<rod>>;
 
     /// How to link to the entries in the data stores
     using transform_link = typename transform_store<>::link_type;

core/include/detray/geometry/surface.hpp

@@ -325,7 +325,8 @@ class surface {
         }
         // Only check, if there is material in the detector
         if (not m_detector.material_store().all_empty()) {
-            if (is_invalid_value(m_desc.material())) {
+            if (m_desc.material().id() != detector_t::materials::id::e_none and
+                m_desc.material().is_invalid_index()) {
                 os << "ERROR: Surface does not have valid material:\n"
                    << *this << std::endl;
                 return false;

core/include/detray/masks/masks.hpp

@@ -181,6 +181,10 @@ class mask {
     DETRAY_HOST_DEVICE
     auto values() const -> const mask_values& { return _values; }
 
+    /// @returns the boundary values
+    DETRAY_HOST_DEVICE
+    auto values() -> mask_values& { return _values; }
+
     /// @returns the volume link - const reference
     DETRAY_HOST_DEVICE
     auto volume_link() const -> const links_type& { return _volume_link; }

core/include/detray/materials/material.hpp

@@ -11,10 +11,11 @@
 #include "detray/definitions/math.hpp"
 #include "detray/definitions/qualifiers.hpp"
 #include "detray/definitions/units.hpp"
+#include "detray/utils/invalid_values.hpp"
 
 // System include(s)
-#include <limits>
 #include <ratio>
+#include <sstream>
 
 namespace detray {
 
@@ -26,7 +27,12 @@ struct homogeneous_material_tag {};
 }  // namespace detail
 
 /// Material State
-enum class material_state { e_solid = 0, e_liquid = 1, e_gas = 2 };
+enum class material_state {
+    e_solid = 0,
+    e_liquid = 1,
+    e_gas = 2,
+    e_unknown = 3
+};
 
 template <typename scalar_t, typename R = std::ratio<1, 1>>
 struct material {
@@ -53,7 +59,7 @@ struct material {
     ///
     /// @param rhs is the right hand side to be compared to
     DETRAY_HOST_DEVICE
-    constexpr bool operator==(const material<scalar_t>& rhs) const {
+    constexpr bool operator==(const material<scalar_t> &rhs) const {
         return (m_x0 == rhs.X0() && m_l0 == rhs.L0() && m_ar == rhs.Ar() &&
                 m_z == rhs.Z());
     }
@@ -105,6 +111,45 @@ struct material {
         }
     }
 
+    /// @returns a string that contains the material details
+    DETRAY_HOST
+    std::string to_string() const {
+        std::stringstream strm;
+        strm << "material: ";
+        strm << " X0: " << m_x0;
+        strm << " | L0: " << m_l0;
+        strm << " | Z: " << m_z;
+
+        strm << " | state: ";
+        switch (m_state) {
+            case material_state::e_solid: {
+                strm << "solid";
+                break;
+            }
+            case material_state::e_liquid: {
+                strm << "liquid";
+                break;
+            }
+            case material_state::e_gas: {
+                strm << "gaseous";
+                break;
+            }
+            default: {
+                strm << "unknown";
+                break;
+            }
+        };
+
+        return strm.str();
+    }
+
+    /// @returns a string stream that prints the material details
+    DETRAY_HOST
+    friend std::ostream &operator<<(std::ostream &os, const material &mat) {
+        os << mat.to_string();
+        return os;
+    }
+
     protected:
     DETRAY_HOST_DEVICE
     constexpr scalar_type mass_to_molar_density(double ar, double mass_rho) {
@@ -119,13 +164,13 @@ struct material {
     }
 
     // Material properties
-    scalar_type m_x0 = std::numeric_limits<scalar_type>::infinity();
-    scalar_type m_l0 = std::numeric_limits<scalar_type>::infinity();
+    scalar_type m_x0 = detail::invalid_value<scalar_type>();
+    scalar_type m_l0 = detail::invalid_value<scalar_type>();
     scalar_type m_ar = 0.f;
     scalar_type m_z = 0.f;
     scalar_type m_mass_rho = 0.f;
     scalar_type m_molar_rho = 0.f;
-    material_state m_state = material_state::e_solid;
+    material_state m_state = material_state::e_unknown;
 };
 
 // Macro for declaring the predefined materials (with Density effect data)

core/include/detray/materials/material_map.hpp

@@ -0,0 +1,29 @@
+/** Detray library, part of the ACTS project (R&D line)
+ *
+ * (c) 2023 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+#pragma once
+
+// Detray include(s)
+#include "detray/definitions/containers.hpp"
+#include "detray/materials/material_slab.hpp"
+#include "detray/surface_finders/grid/grid.hpp"
+#include "detray/tools/grid_factory.hpp"
+
+namespace detray {
+
+/// Definition of binned material
+template <typename axes_shape, typename scalar_t,
+          typename container_t = host_container_types, bool owning = false>
+using material_map = grid<coordinate_axes<axes_shape, owning, container_t>,
+                          material_slab<scalar_t>, simple_serializer, replacer>;
+
+/// How to build material maps of various shapes
+template <typename scalar_t = detray::scalar>
+using material_map_factory =
+    grid_factory<material_slab<scalar_t>, simple_serializer, replacer>;
+
+}  // namespace detray

core/include/detray/materials/material_rod.hpp

@@ -91,6 +91,16 @@ struct material_rod : public detail::homogeneous_material_tag {
         return this->path_segment(cos_inc_angle, approach) / m_material.L0();
     }
 
+    /// @returns a string stream that prints the material details
+    DETRAY_HOST
+    friend std::ostream& operator<<(std::ostream& os, const material_rod& mat) {
+        os << "rod: ";
+        os << mat.get_material().to_string();
+        os << " | radius: " << mat.radius() << "mm";
+
+        return os;
+    }
+
     private:
     material_type m_material = {};
     scalar_type m_radius = std::numeric_limits<scalar>::epsilon();

core/include/detray/materials/material_slab.hpp

@@ -15,6 +15,7 @@
 
 // System include(s)
 #include <limits>
+#include <ostream>
 
 namespace detray {
 
@@ -93,6 +94,17 @@ struct material_slab : public detail::homogeneous_material_tag {
         return m_thickness_in_L0 / cos_inc_angle;
     }
 
+    /// @returns a string stream that prints the material details
+    DETRAY_HOST
+    friend std::ostream& operator<<(std::ostream& os,
+                                    const material_slab& mat) {
+        os << "slab: ";
+        os << mat.get_material().to_string();
+        os << " | thickness: " << mat.thickness() << "mm";
+
+        return os;
+    }
+
     private:
     material_type m_material = {};
     scalar_type m_thickness = std::numeric_limits<scalar>::epsilon();