added environment tree

Environment/BaseEnvironment.h

+#ifndef _include_EnvironmentBase_h
+#define _include_EnvironmentBase_h
+
+#include <vector>
+#include <memory>
+#include <algorithm>
+#include <corsika/geometry/Sphere.h>
+#include <corsika/geometry/Point.h>
+
+namespace corsika::environment {
+
+class BaseEnvironment {
+    std::vector<std::unique_ptr<BaseEnvironment>> childNodes, excludedOverlapNodes;
+    corsika::geometry::Sphere shape;
+    
+public:
+    bool ShapeContains(corsika::geometry::Point const& p) const {
+        return shape.Contains(p);
+    }
+
+    BaseEnvironment* GetContainingNode(corsika::geometry::Point const& p) const {
+        if (!shape.Contains(p))
+        {
+            return nullptr;
+        }
+            
+        auto const predicate = [&] (auto const& s) {return bool(s->GetContainingNode(p));};
+        
+        auto const childFountIt = std::find_if(childNodes.cbegin(), childNodes.cend(), predicate);
+        
+        if (childFoundIt == childNodes.cend())
+        {
+            if (auto const excludedIt = std::find_if(excludedOverlapNodes.cbegin(), excludedOverlapNodes.cend(), predicate); excluded == excludedOverlapNodes.cend())
+            {
+                return *this;
+            }
+            else
+            {
+                return excludedIt;
+            }
+        }
+        
+        return (*childFoundIt)->GetContainingNode(p);
+    }
+
+    /**
+     * Get mass density at given point \a p. It is the caller's responsibility
+     * to call this method from the appropriate node in whose domain \a p is located.
+     */
+    virtual MassDensityType GetDensity(corsika::geometry::Point const& p) = 0;
+    
+    virtual std::pair<corsika::particles::Code const*, corsika::particles::Code const*> GetTargetComposition(Point const& p)
+};
+
+}
+
+#endif