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cgal/Visibility_2/include/CGAL/Simple_polygon_visibility_2_.h

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// Copyright (c) 2013 Technical University Braunschweig (Germany).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
// You can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation,
// either version 3 of the License, or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
//
// Author(s): Francisc Bungiu <fbungiu@gmail.com>
// Michael Hemmer <michael.hemmer@cgal.org>
#ifndef CGAL_SIMPLE_POLYGON_VISIBILITY_2__H
#define CGAL_SIMPLE_POLYGON_VISIBILITY_2__H
#include <CGAL/Arrangement_2.h>
#include <CGAL/rational_rotation.h>
#include <CGAL/tags.h>
#include <CGAL/enum.h>
#include <CGAL/Visibility_2/visibility_utils.h>
#include <stack>
#include <map>
namespace CGAL {
template<class Arrangement_2, class RegularizationTag>
class Simple_polygon_visibility_2_ {
public:
// Currently only consider with same type for both
typedef Arrangement_2 Arrangement_2;
typedef Arrangement_2 Visibility_arrangement_2;
typedef typename Arrangement_2::Geometry_traits_2 Geometry_traits_2;
typedef typename Arrangement_2::Halfedge_const_handle
Halfedge_const_handle;
typedef typename Arrangement_2::Halfedge_handle Halfedge_handle;
typedef typename Arrangement_2::Ccb_halfedge_const_circulator
Ccb_halfedge_const_circulator;
typedef typename Arrangement_2::Face_const_handle Face_const_handle;
typedef typename Arrangement_2::Face_handle Face_handle;
typedef typename Geometry_traits_2::Point_2 Point_2;
typedef typename Geometry_traits_2::Ray_2 Ray_2;
typedef typename Geometry_traits_2::Segment_2 Segment_2;
typedef typename Geometry_traits_2::Line_2 Line_2;
typedef typename Geometry_traits_2::Vector_2 Vector_2;
typedef typename Geometry_traits_2::Direction_2 Direction_2;
typedef typename Geometry_traits_2::FT Number_type;
typedef typename Geometry_traits_2::Object_2 Object_2;
typedef RegularizationTag Regularization_tag;
typedef CGAL::Tag_false Supports_general_polygon_tag;
typedef CGAL::Tag_true Supports_simple_polygon_tag;
Simple_polygon_visibility_2_() : p_arr(NULL), geom_traits(NULL) {};
/*! Constructor given an arrangement and the Regularization tag. */
Simple_polygon_visibility_2_(const Arrangement_2& arr):
p_arr(&arr) {
geom_traits = p_arr->geometry_traits();
};
bool is_attached() {
return (p_arr != NULL);
}
void attach(const Arrangement_2& arr) {
p_arr = &arr;
geom_traits = p_arr->geometry_traits();
}
void detach() {
p_arr = NULL;
geom_traits = NULL;
vertices.clear();
}
const Arrangement_2& arr() {
return *p_arr;
}
Face_handle compute_visibility(const Point_2& q, const Face_const_handle face,
Visibility_arrangement_2& out_arr) {
CGAL::Visibility_2::print_arrangement_by_face<Arrangement_2>(*p_arr);
typename Arrangement_2::Ccb_halfedge_const_circulator circ =
face->outer_ccb();
typename Arrangement_2::Ccb_halfedge_const_circulator curr = circ;
typename Arrangement_2::Halfedge_const_handle he = curr;
std::vector<Point_2> temp_vertices;
Point_2 min_intersect_pt;
bool intersect_on_endpoint = false;
Segment_2 curr_edge(he->source()->point(), he->target()->point());
Segment_2 curr_min_edge(he->source()->point(), he->target()->point());
Point_2 curr_vertex = he->target()->point();
temp_vertices.push_back(curr_vertex);
Number_type min_dist = CGAL::Visibility_2::Compute_squared_distance_2
<Geometry_traits_2, Point_2, Segment_2>(geom_traits, q, curr_edge);
int min_dist_index = 0;
int index = 1;
curr++;
// Push all vertices and determine edge minimum in terms
// of squared distance to query point
do {
he = curr;
curr_edge = Segment_2(he->source()->point(), he->target()->point());
Number_type curr_dist = CGAL::Visibility_2::Compute_squared_distance_2
<Geometry_traits_2, Point_2, Segment_2>(geom_traits, q, curr_edge);
if (curr_dist < min_dist) {
min_dist = curr_dist;
min_dist_index = index;
curr_min_edge = curr_edge;
}
temp_vertices.push_back(he->target()->point());
index++;
} while (++curr != circ);
// Only now compute the intersection point
min_intersect_pt = CGAL::Visibility_2::Construct_projected_point_2
<Geometry_traits_2, Segment_2, Point_2>(geom_traits, curr_min_edge, q);
bool intersect_pt_on_seg_endpoint = false;
if (min_intersect_pt != curr_min_edge.source() &&
min_intersect_pt != curr_min_edge.target()) {
vertices.push_back(min_intersect_pt);
}
else {
intersect_pt_on_seg_endpoint = true;
}
// Now create vector so that first vertex v0 is visible
for (unsigned int k = min_dist_index ; k < temp_vertices.size() ; k++) {
vertices.push_back(temp_vertices[k]);
}
for (unsigned int k = 0 ; k < min_dist_index ; k++) {
vertices.push_back(temp_vertices[k]);
}
// Push first vertex again to fulfill algo precondition
if (min_intersect_pt != curr_min_edge.source() &&
min_intersect_pt != curr_min_edge.target()) {
vertices.push_back(min_intersect_pt);
}
else {
vertices.push_back(vertices[0]);
}
std::cout << "******VERTICES***************\n";
for (unsigned int i = 0 ; i < vertices.size() ; i++) {
std::cout << vertices[i] << std::endl;
}
std::cout << "*********************\n";
compute_angular_displacement(q);
print_angular_displacement();
visibility_region_impl(q);
typename std::vector<Point_2> points;
if (!s.empty()) {
Point_2 prev_pt = s.top();
if (prev_pt == min_intersect_pt) {
if (intersect_pt_on_seg_endpoint) {
points.push_back(prev_pt);
}
s.pop();
if (!s.empty()) {
prev_pt = s.top();
points.push_back(prev_pt);
}
}
if (!s.empty()) {
s.pop();
}
while(!s.empty()) {
Point_2 curr_pt = s.top();
if (curr_pt == min_intersect_pt) {
if (intersect_pt_on_seg_endpoint) {
points.push_back(curr_pt);
}
s.pop();
}
else {
points.push_back(curr_pt);
prev_pt = curr_pt;
s.pop();
}
}
}
std::reverse(points.begin(), points.end());
std::cout << "POINTS\n";
for (unsigned int k = 0 ; k < points.size() ; k++) {
std::cout << points[k] << std::endl;
}
std::cout << "END POINTS\n";
CGAL::Visibility_2::report_while_handling_needles
<Simple_polygon_visibility_2_>(geom_traits,
q,
points,
out_arr);
std::cout << "OUTPUT\n";
CGAL::Visibility_2::print_arrangement_by_face<Visibility_arrangement_2>(out_arr);
std::cout << "END OUTPUT\n";
CGAL_precondition(out_arr.number_of_isolated_vertices() == 0);
CGAL_precondition(s.size() == 0);
conditional_regularize(out_arr, Regularization_tag());
vertices.clear();
if (out_arr.faces_begin()->is_unbounded()) {
return ++out_arr.faces_begin();
}
else {
return out_arr.faces_begin();
}
}
Face_handle compute_visibility(const Point_2& q, const Halfedge_const_handle he,
Visibility_arrangement_2& out_arr ) {
/*
query_pt_is_vertex = false;
if (q != he->source()->point()) {
if (q != he->target()->point()) {
vertices.push_back(q);
vertices.push_back(he->target()->point());
}
else {
vertices.push_back(q);
query_pt_is_vertex = true;
}
}
typename Arrangement_2::Face_const_handle face = he->face();
typename Arrangement_2::Ccb_halfedge_const_circulator circ =
face->outer_ccb();
typename Arrangement_2::Ccb_halfedge_const_circulator curr;
typename Arrangement_2::Halfedge_const_handle he_handle = circ;
while (he_handle != he) {
circ++;
he_handle = circ;
}
circ++;
curr = circ;
do {
he_handle = curr;
Point_2 curr_vertex = he_handle->target()->point();
vertices.push_back(curr_vertex);
} while (++curr != circ);
vertices.pop_back();
vertices.push_back(vertices[0]);
std::cout << "******VERTICES***************\n";
for (unsigned int i = 0 ; i < vertices.size() ; i++) {
std::cout << vertices[i] << std::endl;
}
std::cout << "*********************\n";
visibility_region_impl(q);
std::cout << "STACK\n";
while (!s.empty()) {
std::cout << s.top() << std::endl;
s.pop();
}
std::cout << "END STACK\n";
typename std::vector<Point_2> points;
if (!s.empty()) {
Point_2 prev_pt = s.top();
if (prev_pt != q) {
points.push_back(prev_pt);
}
else if (query_pt_is_vertex) {
points.push_back(prev_pt);
}
if (!s.empty()) {
s.pop();
}
while(!s.empty()) {
Point_2 curr_pt = s.top();
if (curr_pt != q) {
points.push_back(curr_pt);
}
else if (query_pt_is_vertex) {
points.push_back(curr_pt);
}
s.pop();
}
}
std::reverse(points.begin(), points.end());
std::cout << "POINTS\n";
for (unsigned int i = 0 ; i < points.size() ; i++) {
std::cout << points[i] << std::endl;
}
std::cout << "*****************\n";
CGAL::Visibility_2::report_while_handling_needles
<Simple_polygon_visibility_2>(geom_traits,
q,
points,
out_arr);
CGAL_precondition(out_arr.number_of_isolated_vertices() == 0);
CGAL_precondition(s.size() == 0);
conditional_regularize(out_arr, Regularization_tag());
vertices.clear();
// CGAL::Visibility_2::print_arrangement_by_face<Visibility_arrangement_2>(out_arr);
if (out_arr.faces_begin()->is_unbounded()) {
return ++out_arr.faces_begin();
}
else {
return out_arr.faces_begin();
}*/
}
private:
const Arrangement_2 *p_arr;
const Geometry_traits_2 *geom_traits;
std::stack<Point_2> s;
std::vector<Point_2> vertices;
std::map<Point_2, double> angular_displacement;
std::pair<Point_2, double> angular_displacement_vn;
enum {ADVANCE, SCAN, RETARD, FINISH} upcase;
enum {RAY, SEGMENT} polar_mode;
bool do_overlap(const Point_2& a, const Point_2& b, const Point_2& c) {
if (CGAL::Visibility_2::Collinear(geom_traits, a, b, c)) {
Segment_2 s1(a, b);
Segment_2 s2(a, c);
const Segment_2 *seg_overlap;
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Segment_2>(geom_traits, s1, s2);
if (seg_overlap = CGAL::object_cast<Segment_2>(&result)) {
return true;
}
}
return false;
}
void conditional_regularize(Visibility_arrangement_2& out_arr, CGAL::Tag_true) {
regularize_output(out_arr);
}
void conditional_regularize(Visibility_arrangement_2& out_arr, CGAL::Tag_false) {
//do nothing
}
double angle(const Point_2& r, const Point_2& p, const Point_2& q) {
}
void compute_angular_displacement(const Point_2& q) {
Point_2 v0 = vertices[0];
angular_displacement.insert(std::pair<Point_2, double>(v0, 0));
for (unsigned int k = 1 ; k < vertices.size() ; k++) {
Vector_2 vec1(vertices[k-1].x() - q.x(), vertices[k-1].y() - q.y());
Vector_2 vec2(vertices[k].x() - q.x(), vertices[k].y() - q.y());
Number_type scalar_prod = vec1*vec2;
Number_type len1 = vec1.squared_length();
Number_type len2 = vec2.squared_length();
double angle = acos(CGAL::to_double(scalar_prod)/
sqrt(CGAL::to_double(len1*len2)));
switch(CGAL::Visibility_2::Orientation_2(geom_traits,
q,
vertices[k-1],
vertices[k])) {
case CGAL::LEFT_TURN:
if (k == vertices.size() - 1) {
angular_displacement_vn = std::make_pair(vertices[k],
angular_displacement[vertices[k-1]] + angle);
}
else {
angular_displacement.insert(std::pair<Point_2, double>(vertices[k],
angular_displacement[vertices[k-1]] + angle));
}
break;
case CGAL::RIGHT_TURN:
if (k == vertices.size() - 1) {
angular_displacement_vn = std::make_pair(vertices[k],
angular_displacement[vertices[k-1]] - angle);
}
else {
angular_displacement.insert(std::pair<Point_2, double>(vertices[k],
angular_displacement[vertices[k-1]] - angle));
}
break;
case CGAL::COLLINEAR:
if (k == vertices.size() - 1) {
angular_displacement_vn = std::make_pair(vertices[k],
angular_displacement[vertices[k-1]]);
}
else {
angular_displacement.insert(std::pair<Point_2, double>(vertices[k],
angular_displacement[vertices[k-1]]));
}
break;
}
}
}
double get_angular_displacement(const Point_2& pt, const int i) {
if (i == vertices.size() - 1) {
return angular_displacement_vn.second;
}
else {
return angular_displacement[pt];
}
}
void print_angular_displacement() {
typename std::map<Point_2, double>::iterator it = angular_displacement.begin();
for (it ; it != angular_displacement.end() ; it++) {
std::cout << it->first << " - " << it->second << std::endl;
}
std::cout << angular_displacement_vn.first << " - "
<< angular_displacement_vn.second << std::endl;
}
void regularize_output(Visibility_arrangement_2& out_arr) {
typename Visibility_arrangement_2::Edge_iterator e_itr;
for (e_itr = out_arr.edges_begin() ;
e_itr != out_arr.edges_end() ; e_itr++) {
Halfedge_handle he = e_itr;
Halfedge_handle he_twin = he->twin();
if (he->face() == he_twin->face()) {
out_arr.remove_edge(he);
}
}
}
void visibility_region_impl(const Point_2& q) {
int i = 0;
Point_2 w;
bool ccw = false;
s.push(vertices[0]);
if (angular_displacement[vertices[1]] >= angular_displacement[vertices[0]]){
upcase = ADVANCE;
}
else {
upcase = SCAN;
ccw = true;
w = Point_2(vertices[0]);
polar_mode = RAY;
}
while (upcase != FINISH) {
switch(upcase) {
case ADVANCE:
advance(q, i, ccw, w);
break;
case RETARD:
retard(q, i, ccw, w);
break;
case SCAN:
scan(q, i, ccw, w);
break;
}
}
}
void advance(const Point_2& q, int& i, bool& ccw, Point_2& w) {
while (upcase == ADVANCE) {
if (get_angular_displacement(vertices[i+1], i+1) <= 2*CGAL_PI) {
i++;
s.push(vertices[i]);
if (i == vertices.size()-1) {
upcase = FINISH;
}
else if (get_angular_displacement(vertices[i+1], i+1) < get_angular_displacement(vertices[i], i)
&& CGAL::Visibility_2::Orientation_2(geom_traits,
vertices[i-1],
vertices[i],
vertices[i+1]) == CGAL::RIGHT_TURN) {
upcase = SCAN;
ccw = true;
w = Point_2(vertices[i]);
polar_mode = RAY;
}
else if (get_angular_displacement(vertices[i+1], i+1) < get_angular_displacement(vertices[i], i)
&& CGAL::Visibility_2::Orientation_2(geom_traits,
vertices[i-1],
vertices[i],
vertices[i+1]) == CGAL::LEFT_TURN) {
upcase = RETARD;
}
}
else {
if (angular_displacement[s.top()] < 2*CGAL_PI) {
// Compute intersection of v[i]v[i+1] and line qv[0]
Segment_2 seg(vertices[i], vertices[i+1]);
Ray_2 ray(q, vertices[0]);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Ray_2>(geom_traits, seg, ray);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
s.push(*ipoint);
angular_displacement.insert(std::make_pair(*ipoint, 2*CGAL_PI));
}
}
upcase = SCAN;
ccw = false;
w = vertices[0];
polar_mode = SEGMENT;
}
}
}
void retard(const Point_2& q, int& i, bool& ccw, Point_2& w) {
while (upcase == RETARD && !s.empty()) {
Point_2 s_j_prev = s.top();
if (!s.empty()) {
s.pop();
Point_2 s_j = s.top();
if (angular_displacement[s_j] < get_angular_displacement(vertices[i+1], i+1)
&& get_angular_displacement(vertices[i+1], i+1) > angular_displacement[s_j]) {
i++;
// Compute intersection of s[j]s[j+1] and line qv[i]
Segment_2 seg(s_j, s_j_prev);
Ray_2 ray(q, vertices[i]);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Ray_2>(geom_traits, seg, ray);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
angular_displacement.insert(std::pair<Point_2, double>(*ipoint, CGAL::to_double(2*CGAL_PI)));
s.push(*ipoint);
}
s.push(vertices[i]);
if (i == vertices.size() - 1) {
upcase = FINISH;
}
else if (get_angular_displacement(vertices[i], i) <= get_angular_displacement(vertices[i+1], i+1)
&& CGAL::Visibility_2::Orientation_2(geom_traits,
vertices[i-1],
vertices[i],
vertices[i+1]) == CGAL::RIGHT_TURN) {
upcase = ADVANCE;
}
else if (get_angular_displacement(vertices[i], i) < get_angular_displacement(vertices[i+1], i+1)
&& CGAL::Visibility_2::Orientation_2(geom_traits,
vertices[i-1],
vertices[i],
vertices[i+1]) == CGAL::LEFT_TURN) {
upcase = SCAN;
ccw = false;
w = vertices[i];
polar_mode = SEGMENT;
s.pop();
}
else {
s.pop();
}
}
else {
if (get_angular_displacement(vertices[i+1], i+1) == angular_displacement[s_j]
&& get_angular_displacement(vertices[i+2], i+2) > get_angular_displacement(vertices[i+1], i+1)
&& CGAL::Visibility_2::Orientation_2(geom_traits,
vertices[i],
vertices[i+1],
vertices[i+2]) == CGAL::RIGHT_TURN) {
upcase = ADVANCE;
i++;
s.push(vertices[i]);
}
else {
Segment_2 seg_fst(vertices[i], vertices[i+1]);
Segment_2 seg_snd(s_j, s_j_prev);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Segment_2>(geom_traits, seg_fst, seg_snd);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
w = *ipoint;
polar_mode = SEGMENT;
upcase = SCAN;
ccw = true;
}
}
}
}
}
}
void scan(const Point_2& q, int& i, bool& ccw, Point_2& w) {
while (upcase == SCAN && i < vertices.size()-2) {
i++;
if (ccw && get_angular_displacement(vertices[i+1], i+1) > angular_displacement[s.top()]
&& angular_displacement[s.top()] >= get_angular_displacement(vertices[i], i)) {
Segment_2 seg(vertices[i], vertices[i+1]);
if (polar_mode == RAY) {
Ray_2 w_ray(q, w);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Ray_2>(geom_traits, seg, w_ray);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
upcase = ADVANCE;
s.push(*ipoint);
}
}
else {
Segment_2 w_seg(s.top(), w);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Segment_2>(geom_traits, seg, w_seg);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
upcase = ADVANCE;
s.push(*ipoint);
}
}
}
else if (!ccw && get_angular_displacement(vertices[i+1], i+1) <= angular_displacement[s.top()]
&& angular_displacement[s.top()] < get_angular_displacement(vertices[i], i)) {
Segment_2 seg(vertices[i], vertices[i+1]);
if (polar_mode == RAY) {
Ray_2 w_ray(q, w);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Ray_2>(geom_traits, seg, w_ray);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
upcase = RETARD;
}
}
else {
Segment_2 w_seg(s.top(), w);
Object_2 result = CGAL::Visibility_2::Intersect_2
<Geometry_traits_2, Segment_2, Segment_2>(geom_traits, seg, w_seg);
if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
upcase = RETARD;
}
}
}
}
}
};
} // namespace CGAL
#endif
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