added so far empty dummy class for NoMagneticField

Environment/CMakeLists.txt

@@ -35,6 +35,7 @@ set (
   ShowerAxis.h
   IMagneticFieldModel.h
   UniformMagneticField.h
+  NoMagneticField.h
   IRefractiveIndexModel.h
   UniformRefractiveIndex.h
   IMediumPropertyModel.h

Environment/NoMagneticField.h

+/*
+ * (c) Copyright 2020 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#pragma once
+
+#include <corsika/environment/IMagneticFieldModel.h>
+#include <corsika/geometry/RootCoordinateSystem.h>
+
+namespace corsika::environment {
+
+  /**
+   * A uniform (constant) magnetic field.
+   *
+   * This class returns the same magnetic field vector
+   * for all evaluated locations.
+   *
+   */
+  template <typename T>
+  class NoMagneticField : public T {
+
+    // a type-alias for a magnetic field vector
+    using MagneticFieldVector =
+        corsika::geometry::Vector<corsika::units::si::magnetic_flux_density_d>;
+
+  public:
+    /**
+     * Construct a NoMagneticField.
+     *
+     * This is initialized with a fixed magnetic field
+     * and returns this magnetic field at all locations.
+     *
+     * @param field    The fixed magnetic field to return.
+     */
+    template <typename... Args>
+    NoMagneticField(Args&&... args)
+        : T(std::forward<Args>(args)...)
+         {}
+
+    /**
+     * Evaluate the magnetic field at a given location.
+     *
+     * @param  point    The location to evaluate the field at.
+     * @returns    The magnetic field vector.
+     */
+    MagneticFieldVector GetMagneticField(
+        corsika::geometry::Point const&) const final override {
+      CoordinateSystem const& gCS =
+	RootCoordinateSystem::GetInstance().GetRootCoordinateSystem();
+      return MagneticFieldVector(gCS, {0_T, 0_T, 0_T});
+    }
+
+  }; // END: class MagneticField
+
+} // namespace corsika::environment