Introduce GeoMaterial sorter helper struct

GeoModelCore/GeoModelHelpers/GeoModelHelpers/GeoMaterialSorter.h

+/*
+  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
+*/
+#ifndef GeoModelHelpers_GeoMaterialSorter_H
+#define GeoModelHelpers_GeoMaterialSorter_H
+
+#include "GeoModelKernel/GeoMaterial.h"
+#include "GeoModelKernel/GeoElement.h"
+#include "GeoModelKernel/GeoIntrusivePtr.h"
+#include <set>
+
+/// @brief  Helper struct to deuplicate equivalent materials with different naming
+struct GeoMaterialSorter {
+    /** @brief Comparison operator returing whether Material A is smaller than Material B */
+    bool operator()(const GeoMaterial* a, const GeoMaterial* b) const;
+    /** @brief Comparison operator returing whether the Element A is smaller than Element B */
+    bool operator()(const GeoElement* a, const GeoElement* b) const;
+    /// @brief Compares 2  GeoMaterials
+    /// @param a : Pointer to material A
+    /// @param b : Pointer to material B
+    /// @return  Returns 0 if no defining material property could be found that differs
+    ///          Returns -1 if the first defining & differing property of A is smaller
+    ///          Returns 1 otherwise
+    int compare(const GeoMaterial* a, const GeoMaterial* b) const;
+    int compare(const GeoElement* a, const GeoElement* b) const;
+
+};
+
+/// @brief 
+/// @tparam ShapeType 
+using GeoMaterialSet = std::set<GeoIntrusivePtr<const GeoMaterial>, GeoMaterialSorter>;
+
+#endif
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GeoModelCore/GeoModelHelpers/src/GeoMaterialSorter.cxx

+/*
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
+*/
+
+
+#include "GeoModelHelpers/GeoMaterialSorter.h"
+
+namespace {
+    // Tolerance in density to treat both material equally
+    constexpr double equivTol = 1.e-6;
+}
+
+
+bool GeoMaterialSorter::operator()(const GeoMaterial* a, const GeoMaterial* b) const{
+    return compare(a,b) < 0;
+}
+bool GeoMaterialSorter::operator()(const GeoElement* a, const GeoElement* b) const{
+    return compare(a,b) < 0;
+}
+
+int GeoMaterialSorter::compare(const GeoMaterial* a, const GeoMaterial* b) const {
+    if (a == b) {
+        return 0;
+    }
+    if (a->getNumElements() != b->getNumElements()) {
+        return a->getNumElements() < b->getNumElements();
+    }
+    const double densityCmp = a->getDensity() - b->getDensity();
+    if (std::abs(densityCmp) > equivTol) {
+        return densityCmp < 0. ? -1 : 1; 
+    }
+    /// Assume sorting of elements by fraction
+    for (unsigned e = 0; e < a->getNumElements(); ++e) {
+        const double fracComp = a->getFraction(e) - b->getFraction(e);
+        if (std::abs(fracComp) > equivTol) {
+            return fracComp < 0.? -1: 1;
+        }
+        const int eleCmp = compare(a->getElement(e), b->getElement(e));
+        if (eleCmp) {
+            return eleCmp;
+        }
+    }
+    return 0;
+}
+int GeoMaterialSorter::compare(const GeoElement* a, const GeoElement* b) const {
+    if (a == b) {
+        return 0;
+    }
+    if (a->getZ() != b->getZ()) {
+        return a->getZ() < b->getZ() ? -1 : 1;
+    }
+    if (a->getA() != b->getA()) {
+        return a->getA() < b->getA() ? -1 : 1;
+    } 
+    return 0;
+}
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