inline return_type operator()(P const& p, Segment const& s) const
{
assert_dimension_equal<P, Segment>();
/* Algorithm
POINT v(x2 - x1, y2 - y1);
POINT w(px - x1, py - y1);
c1 = w . v
c2 = v . v
b = c1 / c2
RETURN POINT(x1 + b * vx, y1 + b * vy);
*/
typedef typename boost::remove_const
<
typename point_type<Segment>::type
>::type segment_point_type;
segment_point_type v, w;
// TODO
// ASSUMPTION: segment
// SOLVE THIS USING OTHER FUNCTIONS using get<,>
copy_coordinates(s.second, v);
copy_coordinates(p, w);
subtract_point(v, s.first);
subtract_point(w, s.first);
Strategy strategy;
coordinate_type c1 = dot_product(w, v);
if (c1 <= 0)
{
return strategy(p, s.first);
}
coordinate_type c2 = dot_product(v, v);
if (c2 <= c1)
{
return strategy(p, s.second);
}
// Even in case of char's, we have to turn to a point<double/float>
// because of the division.
coordinate_type b = c1 / c2;
// Note that distances with integer coordinates do NOT work because
// - the project point is integer
// - if we solve that, the used distance_strategy cannot handle double points
segment_point_type projected;
copy_coordinates(s.first, projected);
multiply_value(v, b);
add_point(projected, v);
return strategy(p, projected);
}
inline return_type apply(Point const& p,
PointOfSegment const& p1, PointOfSegment const& p2) const
{
assert_dimension_equal<Point, PointOfSegment>();
/* Algorithm
POINT v(x2 - x1, y2 - y1);
POINT w(px - x1, py - y1);
c1 = w . v
c2 = v . v
b = c1 / c2
RETURN POINT(x1 + b * vx, y1 + b * vy);
*/
// Take here the first point type. It should have a default constructor.
// That is not required for the second point type.
Point v, w;
copy_coordinates(p2, v);
copy_coordinates(p, w);
subtract_point(v, p1);
subtract_point(w, p1);
Strategy strategy;
coordinate_type zero = coordinate_type();
coordinate_type c1 = dot_product(w, v);
if (c1 <= zero)
{
return strategy.apply(p, p1);
}
coordinate_type c2 = dot_product(v, v);
if (c2 <= c1)
{
return strategy.apply(p, p2);
}
// Even in case of char's, we have to turn to a point<double/float>
// because of the division.
typedef typename geometry::select_most_precise<coordinate_type, double>::type divisor_type;
divisor_type b = c1 / c2;
// Note that distances with integer coordinates do NOT work because
// - the project point is integer
// - if we solve that, the used distance_strategy cannot handle double points
PointOfSegment projected;
copy_coordinates(p1, projected);
multiply_value(v, b);
add_point(projected, v);
return strategy.apply(p, projected);
}
static inline void apply(G& geometry, P const& point, int , int )
{
typename point_type<G>::type point_type;
copy_coordinates(point, point_type);
geometry.push_back(point_type);
}
inline bool range_ok(Range const& range, Point& centroid)
{
std::size_t const n = boost::size(range);
if (n > 1)
{
return true;
}
else if (n <= 0)
{
#if defined(CENTROID_WITH_CATCH)
throw centroid_exception();
#endif
return false;
}
else // if (n == 1)
{
// Take over the first point in a "coordinate neutral way"
copy_coordinates(range.front(), centroid);
return false;
}
return true;
}
OutputIterator clip_linestring_with_box(Box const& b, Linestring const& linestring,
OutputIterator out, Strategy const& strategy)
{
if (boost::begin(linestring) == boost::end(linestring))
{
return out;
}
typedef typename point_type<OutputLinestring>::type point_type;
OutputLinestring line_out;
typedef typename boost::range_const_iterator<Linestring>::type iterator_type;
iterator_type vertex = boost::begin(linestring);
for(iterator_type previous = vertex++;
vertex != boost::end(linestring);
previous = vertex++)
{
point_type p1, p2;
copy_coordinates(*previous, p1);
copy_coordinates(*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;
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))
{
geometry::append(line_out, p1);
}
geometry::append(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;
}
static inline void apply(Point const& point, PointCentroid& centroid,
Strategy const&)
{
copy_coordinates(point, centroid);
}