chore: move nested Support to ProtoSupport (#2497)

This PR is part 2 of the odd + detector series:
- it promotes the `LayerStructure::Support` to `ProtoSupport`, just as
done with the `ProtoBinning`.

It sits on top of #2496 and is thus marked blocked.

Core/include/Acts/Detector/LayerStructureBuilder.hpp

@@ -11,6 +11,7 @@
 #include "Acts/Definitions/Algebra.hpp"
 #include "Acts/Detector/DetectorComponents.hpp"
 #include "Acts/Detector/ProtoBinning.hpp"
+#include "Acts/Detector/ProtoSupport.hpp"
 #include "Acts/Detector/interface/IInternalStructureBuilder.hpp"
 #include "Acts/Detector/interface/ISurfacesProvider.hpp"
 #include "Acts/Geometry/GeometryContext.hpp"
@@ -72,20 +73,6 @@ class LayerStructureBuilder : public IInternalStructureBuilder {
     std::vector<std::shared_ptr<Surface>> m_surfaces = {};
   };
 
-  /// @brief Support parameter definitions
-  struct Support {
-    /// Define whether you want to build support structures
-    std::array<ActsScalar, 5u> values = {};
-    /// The surface type to be built
-    Surface::SurfaceType type = Surface::SurfaceType::Other;
-    /// Define in which values the support should be constrained
-    std::vector<BinningValue> constraints = s_binningValues;
-    /// Potential splits into planar approximations
-    unsigned int splits = 1u;
-    /// The (optional) layer transform
-    std::optional<Transform3> transform = std::nullopt;
-  };
-
   /// @brief Configuration struct for the LayerStructureBuilder
   ///
   /// It contain:
@@ -96,7 +83,7 @@ class LayerStructureBuilder : public IInternalStructureBuilder {
     /// Connection point for a function to provide surfaces
     std::shared_ptr<ISurfacesProvider> surfacesProvider = nullptr;
     /// Definition of Supports
-    std::vector<Support> supports = {};
+    std::vector<ProtoSupport> supports = {};
     /// Definition of Binnings
     std::vector<ProtoBinning> binnings = {};
     /// Polyhedron approximations

Core/include/Acts/Detector/ProtoSupport.hpp

@@ -0,0 +1,43 @@
+// This file is part of the Acts project.
+//
+// Copyright (C) 2023 CERN for the benefit of the Acts project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#pragma once
+
+#include "Acts/Definitions/Algebra.hpp"
+#include "Acts/Definitions/Common.hpp"
+#include "Acts/Surfaces/Surface.hpp"
+#include "Acts/Utilities/BinningData.hpp"
+#include "Acts/Utilities/detail/AxisFwd.hpp"
+
+#include <optional>
+#include <stdexcept>
+#include <vector>
+
+namespace Acts {
+
+namespace Experimental {
+/// @brief Support parameter definitions
+struct ProtoSupport {
+  /// Define whether you want to build support structures
+  std::array<ActsScalar, 5u> values = {};
+  /// The surface type to be built
+  Surface::SurfaceType type = Surface::SurfaceType::Other;
+  /// Define in which values the support should be constrained
+  std::vector<BinningValue> constraints = s_binningValues;
+  /// Potential splits into planar approximations
+  unsigned int splits = 1u;
+  /// The (optional) layer transform
+  std::optional<Transform3> transform = std::nullopt;
+  /// Alternatively - the support surface can already be provided
+  std::shared_ptr<Surface> surface = nullptr;
+  /// Indicate if the support surface should always be addressed in navigation
+  bool assignToAll = false;
+};
+
+}  // namespace Experimental
+}  // namespace Acts

Core/src/Detector/LayerStructureBuilder.cpp

@@ -167,7 +167,8 @@ Acts::Experimental::LayerStructureBuilder::construct(
   }
 
   // Retrieve the layer surfaces
-  SurfaceCandidatesUpdator internalCandidatesUpdator;
+  SurfaceCandidatesUpdator internalCandidatesUpdator =
+      tryAllPortalsAndSurfaces();
   auto internalSurfaces = m_cfg.surfacesProvider->surfaces(gctx);
   ACTS_DEBUG("Building internal layer structure from "
              << internalSurfaces.size() << " provided surfaces.");
@@ -179,6 +180,17 @@ Acts::Experimental::LayerStructureBuilder::construct(
     ACTS_DEBUG("Adding " << m_cfg.supports.size() << " support structures.")
     // The surface candidate updator
     for (const auto& support : m_cfg.supports) {
+      // Check if the supportsurface has already been built
+      if (support.surface != nullptr) {
+        ACTS_VERBOSE("- Use provided support surface directly.");
+        if (support.assignToAll) {
+          assignToAll.push_back(internalSurfaces.size());
+          ACTS_VERBOSE("  Support surface is assigned to all bins.");
+        }
+        internalSurfaces.push_back(support.surface);
+        continue;
+      }
+
       // Throw an exception is misconfigured
       if (support.type == Surface::SurfaceType::Other) {
         throw std::invalid_argument(
@@ -202,9 +214,11 @@ Acts::Experimental::LayerStructureBuilder::construct(
           support.values, support.transform, support.splits);
     }
   }
-
-  // Create the indexed surface grids
-  if (m_cfg.binnings.size() == 1u) {
+  if (m_cfg.binnings.empty()) {
+    ACTS_DEBUG(
+        "No surface binning provided, navigation will be 'tryAll' (potentially "
+        "slow).");
+  } else if (m_cfg.binnings.size() == 1u) {
     ACTS_DEBUG("- 1-dimensional surface binning detected.");
     // Capture the binning
     auto binning = m_cfg.binnings[0u];

Plugins/TGeo/src/TGeoMaterialConverter.cpp

@@ -25,6 +25,7 @@ Acts::MaterialSlab Acts::TGeoMaterialConverter::materialSlab(
   ActsScalar uScalor = options.unitLengthScalor;
   ActsScalar rScalar =
       options.unitMassScalor / pow(options.unitLengthScalor, 3);
+
   auto material = Material::fromMassDensity(
       matX0 * uScalor / cFactor, matL0 * uScalor / cFactor, tgMaterial.GetA(),
       tgMaterial.GetZ(), matRho * rScalar * cFactor);

Tests/UnitTests/Core/Detector/LayerStructureBuilderTests.cpp

@@ -81,7 +81,7 @@ BOOST_AUTO_TEST_CASE(LayerStructureBuilder_creationRing) {
   BOOST_CHECK(volumes0.empty());
   BOOST_CHECK(volumeUpdator0.connected());
 
-  using LayerSupport = Acts::Experimental::LayerStructureBuilder::Support;
+  using LayerSupport = Acts::Experimental::ProtoSupport;
 
   lsConfig.auxiliary = "*** Endcap with 22 surfaces + 1 support disc ***";
   lsConfig.supports = {LayerSupport{
@@ -148,7 +148,7 @@ BOOST_AUTO_TEST_CASE(LayerStructureBuilder_creationCylinder) {
   BOOST_CHECK(volumes0.empty());
   BOOST_CHECK(volumeUpdator0.connected());
 
-  using LayerSupport = Acts::Experimental::LayerStructureBuilder::Support;
+  using LayerSupport = Acts::Experimental::ProtoSupport;
 
   lsConfig.auxiliary = "*** Barrel with 448 surfaces + 1 support cylinder ***";
   lsConfig.supports = {LayerSupport{{15., 10., 10., 0., 0.},