Ticket #7030: geom_distance.patch

geometry/strategies/spherical/distance_cross_track.hpp

@@ -107 +107 @@
 
         return_type crs_AD = course(sp1, p);
         return_type crs_AB = course(sp1, sp2);
-        return_type XTD = m_radius * geometry::math::abs(asin(sin(d1 / m_radius) * sin(crs_AD - crs_AB)));
 
-#ifdef BOOST_GEOMETRY_DEBUG_CROSS_TRACK
-std::cout << "Course " << dsv(sp1) << " to " << dsv(p) << " " << crs_AD * geometry::math::r2d << std::endl;
-std::cout << "Course " << dsv(sp1) << " to " << dsv(sp2) << " " << crs_AB * geometry::math::r2d << std::endl;
-std::cout << "XTD: " << XTD << " d1: " <<  d1  << " d2: " <<  d2  << std::endl;
+        return_type d_crs = crs_AD - crs_AB;
+
+        if( ( geometry::math::abs( d_crs ) < geometry::math::pi< return_type >() * 0.5 )
+             || ( geometry::math::abs( d_crs ) > geometry::math::pi< return_type >() * 1.5 ) )
+        {
+            return_type XTD = m_radius * geometry::math::abs( asin( sin( d1 / m_radius ) * sin( crs_AD - crs_AB ) ));
+
+ #ifdef BOOST_GEOMETRY_DEBUG_CROSS_TRACK
+            std::cout << "Course " << dsv(sp1) << " to " << dsv(p) << " " << crs_AD * geometry::math::r2d << std::endl;
+            std::cout << "Course " << dsv(sp1) << " to " << dsv(sp2) << " " << crs_AB * geometry::math::r2d << std::endl;
+            std::cout << "XTD: " << XTD << " d1: " <<  d1  << " d2: " <<  d2  << std::endl;
 #endif
 
+            // Return shortest distance, projected point on segment sp1-sp2
+            return return_type( XTD );
+        }
+        else
+        {
+ #ifdef BOOST_GEOMETRY_DEBUG_CROSS_TRACK
+            std::cout << "Course " << dsv(sp1) << " to " << dsv(p) << " " << crs_AD * geometry::math::r2d << std::endl;
+            std::cout << "Course " << dsv(sp1) << " to " << dsv(sp2) << " " << crs_AB * geometry::math::r2d << std::endl;
+#endif
 
-        // Return shortest distance, either to projected point on segment sp1-sp2, or to sp1, or to sp2
-        return return_type((std::min)((std::min)(d1, d2), XTD));
+            // Return shortest distance, either to sp1, or to sp2
+            return return_type( std::min( d1 , d2 ) );
+        }
+
     }
 
     inline return_type radius() const { return m_radius; }