OutputIterator clip_range_with_box(Box const& b, Range const& range, RobustPolicy const&, OutputIterator out, Strategy const& strategy) { if (boost::begin(range) == boost::end(range)) { return out; } typedef typename point_type<OutputLinestring>::type point_type; OutputLinestring line_out; typedef typename boost::range_iterator<Range const>::type iterator_type; iterator_type vertex = boost::begin(range); for(iterator_type previous = vertex++; vertex != boost::end(range); ++previous, ++vertex) { point_type p1, p2; geometry::convert(*previous, p1); geometry::convert(*vertex, p2); // Clip the segment. Five situations: // 1. Segment is invisible, finish line if any (shouldn't occur) // 2. Segment is completely visible. Add (p1)-p2 to line // 3. Point 1 is invisible (clipped), point 2 is visible. Start new line from p1-p2... // 4. Point 1 is visible, point 2 is invisible (clipped). End the line with ...p2 // 5. Point 1 and point 2 are both invisible (clipped). Start/finish an independant line p1-p2 // // This results in: // a. if p1 is clipped, start new line // b. if segment is partly or completely visible, add the segment // c. if p2 is clipped, end the line bool c1 = false; bool c2 = false; model::referring_segment<point_type> s(p1, p2); if (!strategy.clip_segment(b, s, c1, c2)) { strategy.apply(line_out, out); } else { // a. If necessary, finish the line and add a start a new one if (c1) { strategy.apply(line_out, out); } // b. Add p1 only if it is the first point, then add p2 if (boost::empty(line_out)) { detail::overlay::append_no_duplicates(line_out, p1, true); } detail::overlay::append_no_duplicates(line_out, p2); // c. If c2 is clipped, finish the line if (c2) { strategy.apply(line_out, out); } } } // Add last part strategy.apply(line_out, out); return out; }