[buffer] harmonize number of points

include/boost/geometry/strategies/buffer.hpp

@@ -6,8 +6,10 @@
 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_HPP
+#ifndef BOOST_GEOMETRY_STRATEGIES_BUFFER_HPP
-#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_HPP
+#define BOOST_GEOMETRY_STRATEGIES_BUFFER_HPP
+
+#include <cstdint>
 
 namespace boost { namespace geometry
 {
@@ -55,6 +57,27 @@ namespace strategy { namespace buffer
 */
 enum buffer_side_selector { buffer_side_left, buffer_side_right };
 
+// Default number of points in a circle
+constexpr std::size_t default_points_per_circle = 90u;
+
+inline std::size_t get_point_count_for_join(std::size_t count)
+{
+    std::size_t const min_count = 4u;
+    return count > min_count ? count : min_count;
+}
+
+inline std::size_t get_point_count_for_end(std::size_t count)
+{
+    std::size_t const min_count = 4u;
+    return count > min_count ? count : min_count;
+}
+
+inline std::size_t get_point_count_for_circle(std::size_t count)
+{
+    std::size_t const min_count = 3u;
+    return count > min_count ? count : min_count;
+}
+
 /*!
 \brief Enumerates types of pieces (parts of buffer) around geometries
 \ingroup enum
@@ -101,4 +124,4 @@ enum result_code
 
 }} // namespace boost::geometry
 
-#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_HPP
+#endif // BOOST_GEOMETRY_STRATEGIES_BUFFER_HPP

include/boost/geometry/strategies/cartesian/buffer_end_round.hpp

@@ -98,10 +98,9 @@ private :
 public :
 
     //! \brief Constructs the strategy
-    //! \param points_per_circle points which would be used for a full circle
+    //! \param points_per_circle Number of points (minimum 4) that would be used for a full circle
-    //! (if points_per_circle is smaller than 4, it is internally set to 4)
+    explicit inline end_round(std::size_t points_per_circle = default_points_per_circle)
-    explicit inline end_round(std::size_t points_per_circle = 90)
+        : m_points_per_circle(get_point_count_for_end(points_per_circle))
-        : m_points_per_circle((points_per_circle < 4u) ? 4u : points_per_circle)
     {}
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS

include/boost/geometry/strategies/cartesian/buffer_join_round.hpp

@@ -58,9 +58,9 @@ class join_round
 public :
 
     //! \brief Constructs the strategy
-    //! \param points_per_circle points which would be used for a full circle
+    //! \param points_per_circle Number of points (minimum 4) that would be used for a full circle
-    explicit inline join_round(std::size_t points_per_circle = 90)
+    explicit inline join_round(std::size_t points_per_circle = default_points_per_circle)
-        : m_points_per_circle(points_per_circle)
+        : m_points_per_circle(get_point_count_for_join(points_per_circle))
     {}
 
 private :

include/boost/geometry/strategies/cartesian/buffer_point_circle.hpp

@@ -57,10 +57,9 @@ class point_circle
 {
 public :
     //! \brief Constructs the strategy
-    //! \param count number of points for the created circle (if count
+    //! \param count Number of points (minimum 3) for the created circle
-    //! is smaller than 3, count is internally set to 3)
+    explicit point_circle(std::size_t count = default_points_per_circle)
-    explicit point_circle(std::size_t count = 90)
+        : m_count(get_point_count_for_circle(count))
-        : m_count((count < 3u) ? 3u : count)
     {}
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS

include/boost/geometry/strategies/geographic/buffer_end_round.hpp

@@ -38,10 +38,9 @@ class geographic_end_round
 public :
 
     //! \brief Constructs the strategy
-    //! \param points_per_circle Number of points which would be used for a full circle
+    //! \param points_per_circle Number of points (minimum 4) that would be used for a full circle
-    //! (if points_per_circle is smaller than 4, it is internally set to 4)
+    explicit inline geographic_end_round(std::size_t points_per_circle = default_points_per_circle)
-    explicit inline geographic_end_round(std::size_t points_per_circle = 90)
+        : m_points_per_circle(get_point_count_for_end(points_per_circle))
-        : m_points_per_circle((points_per_circle < 4u) ? 4u : points_per_circle)
     {}
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS

include/boost/geometry/strategies/geographic/buffer_join_round.hpp

@@ -38,10 +38,9 @@ class geographic_join_round
 public :
 
     //! \brief Constructs the strategy
-    //! \param points_per_circle Number of points which would be used for a full circle
+    //! \param points_per_circle Number of points (minimum 4) that would be used for a full circle
-    //! (if points_per_circle is smaller than 4, it is internally set to 4)
+    explicit inline geographic_join_round(std::size_t points_per_circle = default_points_per_circle)
-    explicit inline geographic_join_round(std::size_t points_per_circle = 90)
+        : m_points_per_circle(get_point_count_for_join(points_per_circle))
-        : m_points_per_circle((points_per_circle < 4u) ? 4u : points_per_circle)
     {}
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS

include/boost/geometry/strategies/geographic/buffer_point_circle.hpp

@@ -61,10 +61,9 @@ class geographic_point_circle
 public :
 
     //! \brief Constructs the strategy
-    //! \param points_per_circle Number of points for a full circle
+    //! \param count Number of points (minimum 3) for the created circle
-    //! (if points_per_circle is smaller than 3, it is internally set to 3)
+    explicit geographic_point_circle(std::size_t count = default_points_per_circle)
-    explicit geographic_point_circle(std::size_t points_per_circle = 90)
+        : m_count(get_point_count_for_circle(count))
-        : m_points_per_circle((points_per_circle < 3u) ? 3u : points_per_circle)
     {}
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
@@ -97,10 +96,10 @@ public :
         calc_t const two_pi = geometry::math::two_pi<calc_t>();
         calc_t const pi = geometry::math::pi<calc_t>();
 
-        calc_t const diff = two_pi / calc_t(m_points_per_circle);
+        calc_t const diff = two_pi / calc_t(m_count);
         calc_t angle = -pi;
 
-        for (std::size_t i = 0; i < m_points_per_circle; i++, angle += diff)
+        for (std::size_t i = 0; i < m_count; i++, angle += diff)
         {
             // If angle is zero, shift angle a tiny bit to avoid spikes.
             calc_t const eps = angle == 0 ? 1.0e-10 : 0.0;
@@ -116,7 +115,7 @@ public :
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
 private :
-    std::size_t m_points_per_circle;
+    std::size_t m_count;
     Spheroid m_spheroid;
 };
 

test/algorithms/buffer/buffer_polygon.cpp

@@ -715,11 +715,11 @@ void test_all()
                 sharp_triangle,
                 join_round(12), end_flat, distance(1.0), side_strategy, point_strategy,
                 29.1604);
-        // Test very various number of points (min is 3)
+        // Test very various number of points (min is 4)
         test_with_custom_strategies<polygon_type, polygon_type>("sharp_triangle_j2",
                 sharp_triangle,
                 join_round(2), end_flat, distance(1.0), side_strategy, point_strategy,
-                27.2399);
+                28.6161);
         test_with_custom_strategies<polygon_type, polygon_type>("sharp_triangle_j5",
                 sharp_triangle,
                 join_round(5), end_flat, distance(1.0), side_strategy, point_strategy,
@@ -758,10 +758,6 @@ void test_all()
 
         // Right triangles, testing both points around sharp corner as well as points
         // around right corners in join_round strategy
-        test_with_custom_strategies<polygon_type, polygon_type>("right_triangle_j3",
-                right_triangle,
-                join_round(3), end_flat, distance(1.0), side_strategy, point_strategy,
-                53.0240);
         test_with_custom_strategies<polygon_type, polygon_type>("right_triangle_j4",
                 right_triangle,
                 join_round(4), end_flat, distance(1.0), side_strategy, point_strategy,