From db938dbd74460e7a0fd705be8628984052f71dc0 Mon Sep 17 00:00:00 2001
From: ROUVREAU Vincent <vincent.rouvreau@inria.fr>
Date: Fri, 4 Sep 2020 17:23:16 +0200
Subject: Alpha_kernel_d, its tests and Alpha complex to use it

---
 .../include/gudhi/Alpha_complex/Alpha_kernel_d.h   | 137 +++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 src/Alpha_complex/include/gudhi/Alpha_complex/Alpha_kernel_d.h

(limited to 'src/Alpha_complex/include/gudhi/Alpha_complex/Alpha_kernel_d.h')

diff --git a/src/Alpha_complex/include/gudhi/Alpha_complex/Alpha_kernel_d.h b/src/Alpha_complex/include/gudhi/Alpha_complex/Alpha_kernel_d.h
new file mode 100644
index 00000000..87604ec4
--- /dev/null
+++ b/src/Alpha_complex/include/gudhi/Alpha_complex/Alpha_kernel_d.h
@@ -0,0 +1,137 @@
+/*    This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
+ *    See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
+ *    Author(s):       Vincent Rouvreau
+ *
+ *    Copyright (C) 2020 Inria
+ *
+ *    Modification(s):
+ *      - YYYY/MM Author: Description of the modification
+ */
+
+#ifndef ALPHA_COMPLEX_ALPHA_KERNEL_D_H_
+#define ALPHA_COMPLEX_ALPHA_KERNEL_D_H_
+
+#include <CGAL/Epeck_d.h>  // For EXACT or SAFE version
+#include <CGAL/Epick_d.h>  // For FAST version
+#include <CGAL/version.h>  // for CGAL_VERSION_NR
+
+#include <Eigen/src/Core/util/Macros.h>  // for EIGEN_VERSION_AT_LEAST
+
+#include <utility>  // for std::make_pair
+
+// Make compilation fail - required for external projects - https://github.com/GUDHI/gudhi-devel/issues/10
+#if CGAL_VERSION_NR < 1041101000
+# error Alpha_complex is only available for CGAL >= 4.11
+#endif
+
+#if !EIGEN_VERSION_AT_LEAST(3,1,0)
+# error Alpha_complex is only available for Eigen3 >= 3.1.0 installed with CGAL
+#endif
+
+namespace Gudhi {
+
+namespace alpha_complex {
+
+template < typename Kernel, bool Weighted = false >
+class Alpha_kernel_d {
+};
+
+// Unweighted Kernel_d version
+template < typename Kernel >
+class Alpha_kernel_d<Kernel, false> {
+ private:
+  // Kernel for functions access.
+  Kernel kernel_;
+ public:
+  // Fake type for compilation to succeed (cf. std::conditional in Alpha_complex.h)
+  using Weighted_point_d = void;
+  using Point_d = typename Kernel::Point_d;
+  // Numeric type of coordinates in the kernel
+  using FT = typename Kernel::FT;
+  // Sphere is a pair of point and squared radius.
+  using Sphere = typename std::pair<Point_d, FT>;
+
+  int get_dimension(const Point_d& p0) const {
+    return kernel_.point_dimension_d_object()(p0);
+  }
+
+  template<class PointIterator>
+  Sphere get_sphere(PointIterator begin, PointIterator end) const {
+    Point_d c = kernel_.construct_circumcenter_d_object()(begin, end);
+    FT r = kernel_.squared_distance_d_object()(c, *begin);
+    return std::make_pair(std::move(c), std::move(r));
+  }
+
+  template<class PointIterator>
+  FT get_squared_radius(PointIterator begin, PointIterator end) const {
+    return kernel_.compute_squared_radius_d_object()(begin, end);
+  }
+
+  FT get_squared_radius(const Sphere& sph) const {
+    return sph.second;
+  }
+
+  template<class Point>
+  Point get_circumcenter(const Sphere& sph) const {
+    return sph.first;
+  }
+
+  template<class Point>
+  FT get_squared_distance(const Point& first, const Point& second) const {
+    return kernel_.squared_distance_d_object()(first, second);
+  }
+};
+
+// Weighted Kernel_d version
+template < typename Kernel >
+class Alpha_kernel_d<Kernel, true> {
+ private:
+  // Kernel for functions access.
+  Kernel kernel_;
+ public:
+  // Fake type for compilation to succeed (cf. std::conditional in Alpha_complex.h)
+  using Point_d = void;
+  using Weighted_point_d = typename Kernel::Weighted_point_d;
+  using Bare_point_d = typename Kernel::Point_d;
+  // Numeric type of coordinates in the kernel
+  using FT = typename Kernel::FT;
+  // Sphere is a weighted point (point + weight [= squared radius]).
+  using Sphere = Weighted_point_d;
+
+  int get_dimension(const Weighted_point_d& p0) const {
+    return kernel_.point_dimension_d_object()(p0.point());
+  }
+
+  template<class PointIterator>
+  Sphere get_sphere(PointIterator begin, PointIterator end) const {
+    return kernel_.power_center_d_object()(begin, end);
+  }
+
+  template<class PointIterator>
+  FT get_squared_radius(PointIterator begin, PointIterator end) const {
+    Sphere sph = get_sphere(begin, end);
+    return sph.weight();
+  }
+
+  FT get_squared_radius(const Sphere& sph) const {
+    return sph.weight();
+  }
+
+  template<class Point>
+  Point get_circumcenter(const Sphere& sph) const {
+    return sph.point();
+  }
+
+  template<class Point>
+  FT get_squared_distance(const Point& first, const Point& second) const {
+    return kernel_.power_distance_d_object()(first, second);
+  }
+};
+
+}  // namespace alpha_complex
+
+namespace alphacomplex = alpha_complex;
+
+}  // namespace Gudhi
+
+#endif  // ALPHA_COMPLEX_ALPHA_KERNEL_D_H_
\ No newline at end of file
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