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This commit is contained in:
kanhuang 2013-07-31 16:28:26 -04:00
parent 6f6d5b7079
commit fd36bc76c0
3 changed files with 102 additions and 177 deletions
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4
Visibility_2/doc/Visibility_2/CGAL/Triangular_expansion_visibility_2.h
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@ -127,7 +127,7 @@ The visibility region of `q` will be stored in `out_arr`.
\pre `q` is in the interior or on the boundary of the given face `f` \pre `q` is in the interior or on the boundary of the given face `f`
\return the face handle to the face in `out_arr` that represents the visibility region \return the face handle to the face in `out_arr` that represents the visibility region
*/ */
Face_handle visibility_region(const Point_2& q, const Face& f, Output_Arrangement_2& out_arr); Face_handle visibility_region(const Point_2& q, const Face_handle& f, Output_Arrangement_2& out_arr);
/*! /*!
Computes the visibility region for the given query point `q` that is on the side of `halfedge`. Computes the visibility region for the given query point `q` that is on the side of `halfedge`.
@ -139,7 +139,7 @@ The visibility region of `q` will be stored in `out_arr`.
\pre `q` is on halfedge \pre `q` is on halfedge
\return the face handle to the face in `out_arr` that represents the visibility region \return the face handle to the face in `out_arr` that represents the visibility region
*/ */
Face_handle visibility_region(const Point_2& q, const Halfedge& halfedge, Output_Arrangement_2& out_arr); Face_handle visibility_region(const Point_2& q, const Halfedge_handle& halfedge, Output_Arrangement_2& out_arr);
/// @} /// @}

1
Visibility_2/examples/Visibility_2/simple_visibility_2.cpp
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@ -1,4 +1,3 @@
#include <CGAL/tags.h>
#include <CGAL/Exact_predicates_exact_constructions_kernel.h> #include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Arrangement_2.h> #include <CGAL/Arrangement_2.h>
#include <CGAL/Arr_segment_traits_2.h> #include <CGAL/Arr_segment_traits_2.h>

274
Visibility_2/include/CGAL/Naive_visibility_2.h
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@ -71,143 +71,104 @@ public:
//functions //functions
Naive_visibility_2(const Arrangement_2 &arr):arr(arr), attach_tag(true) {} Naive_visibility_2(const Arrangement_2 &arr):arr(arr), attach_tag(true) {}
Naive_visibility_2(): attach_tag(false) {} Naive_visibility_2(): attach_tag(false) {}
void visibility_region(const Point_2 &q, const Halfedge &edge, Arrangement_2 &out_arr) { void visibility_region(const Point_2 &q, const Halfedge_const_handle &edge, Arrangement_2 &out_arr) {
Arrangement_2 arr_c = arr ; //copy of arr;
Halfedge_const_handle eh_c; //copy of edge;
for (Halfedge_const_handle eh = arr_c.edges_begin(); eh != arr_c.edges_begin(); eh++) {
if (eh->source()->point() == edge-> source()->point() && eh->target()->point() == edge->target()->point()) {
eh_c = eh;
break;
}
}
Halfedge a;
if (eh_c->source()->point() == q) {
Vertex_const_handle vh = eh_c->target();
arr_c.remove_edge(eh_c->prev());
arr_c.remove_edge(eh_c);
}
void visibility_region(const Point_2 &query, Face_const_handle fh, Arrangement_2 &out_arr) {
visibility_region_impl(query, fh, out_arr, Regularization_tag());
}
void visibility_region_impl(const Point_2 &query, Face_const_handle fh, Arrangement_2 &out_arr, CGAL::Tag_true) {
std::vector<Vertex_const_handle> vertices; //all vertices of the face.
std::vector<Halfedge_const_handle> edges, active_edges; //edges stores all halfedges of the face; and active_edges stores all halfedges that is currently intersected by the view ray.
//preprocess the face
input_face(fh, vertices, edges, query);
//initiation of vision ray
Vector_2 dir;
if (Direction_2(-1, 0) < Direction_2(Vector_2(query, (*vertices.rbegin())->point())))
{
dir = Vector_2(1, 0) + Vector_2(query, (*vertices.rbegin())->point());
} }
else { else {
dir = Vector_2(0, -1); if (eh_c->target()->point() == q) {
} arr_c.remove_edge(eh_c->next());
Ray_2 init_vision_ray(query, dir); arr_c.remove_edge(eh_c);
//initiation of active_edges
typename std::vector<Halfedge_const_handle>::iterator iter1;
for (iter1 = edges.begin(); iter1 != edges.end(); iter1++)
{
insert_halfedge(active_edges, init_vision_ray, *iter1);
}
//angular sweep
std::vector<Point_2> polygon;
Ray_2 curr_vision_ray = init_vision_ray;
typename std::vector<Vertex_const_handle>::iterator vit = vertices.begin(), begin_it, end_it;
Halfedge_const_handle closest_edge;
bool is_init_empty = active_edges.empty();
while (vit != vertices.end())
{
if (active_edges.empty())
{
begin_it = vit;
end_it = vit;
curr_vision_ray= Ray_2(query, (*begin_it)->point());
Direction_2 d1(curr_vision_ray), d2;
do {
d2 = Direction_2(Ray_2(query, (*end_it)->point()));
if (d1 != d2) break;
} while (++end_it != vertices.end());
add_edges(begin_it, end_it, active_edges, curr_vision_ray);
//since active_edges is empty, that means adding new edges will bring in an unbounded edge to arrangement.
closest_edge = active_edges[0];
remove_edges(active_edges, curr_vision_ray);
if (active_edges.empty()) {
//this means in input, there is no edge that intersects curr_vision_ray
//except those collinear ones.
//because one unbounded ray has been inserted before,
//we don't need to do anything here.
}
else {
//add new edge;
Point_2 p1 = intersection_point(curr_vision_ray, closest_edge);
Point_2 p2 = intersection_point(curr_vision_ray, active_edges[0]);
update_visibility(p1, polygon, out_arr);
update_visibility(p2, polygon, out_arr);
}
} }
else { else {
closest_edge = active_edges[0]; bool is_outbound = eh_c->twin()->face()->is_unbounded();
begin_it = vit; //all vertices between begin_it and end_it(not included) are collinear with query point. Point_2 source = eh_c->source()->point();
end_it = vit; Point_2 target = eh_c->target()->point();
curr_vision_ray = Ray_2(query, (*begin_it)->point()); Halfedge_const_handle eh1 = eh_c->next();
Direction_2 d1(curr_vision_ray), d2; arr_c.remove_edge(eh_c);
do { Face_const_handle fh = eh1->face();
d2 = Direction_2(Ray_2(query, (*end_it)->point()));
if (d1 != d2) break;
} while (++end_it != vertices.end());
add_edges(begin_it, end_it, active_edges, curr_vision_ray);
if (closest_edge != active_edges[0]) std::vector<Point_2> polygon;
{ visibility_region_impl(q, fh, polygon);
//add new edge;
Point_2 p1 = intersection_point(curr_vision_ray, closest_edge);
Point_2 p2 = intersection_point(curr_vision_ray, active_edges[0]);
update_visibility(p1, polygon, out_arr);
update_visibility(p2, polygon, out_arr);
} if (is_outbound) {
build_arr(polygon, out_arr);
closest_edge = active_edges[0];
remove_edges(active_edges, curr_vision_ray);
if (active_edges.empty()) {
//add an unbounded edge
//todo CGAL::insert_curve(out_arr, Ray_2((*begin_it)->point(), Direction_2(curr_vision_ray)));
} }
else { else {
if (closest_edge != active_edges[0]) { int source_i = -1, target_i = -1;
//add new edge; for (int i = 0; i != polygon.size(); i++) {
Point_2 p1 = intersection_point(curr_vision_ray, closest_edge); if ( polygon[i]== source ) {
Point_2 p2 = intersection_point(curr_vision_ray, active_edges[0]); source_i = i;
update_visibility(p1, polygon, out_arr); }
update_visibility(p2, polygon, out_arr); else if ( polygon[i] == target ) {
target_i = i;
}
} }
int small_i, big_i;
if ( source_i < target_i )
{
int next_i = source_i + 1;
while (CGAL::collinear(source, polygon[next_i], target))
next_i++;
if (CGAL::left_turn(source, target, polygon[next_i])) {
}
}
else {
small_i = target_i;
big_i = source_i;
}
if (CGAL::right_turn())
} }
} }
vit = end_it;
}
if (!is_init_empty) {
CGAL::insert(out_arr, Segment_2(polygon[0], polygon.back()));
} }
} }
void visibility_region_impl(const Point_2 &query, Face_const_handle fh, Arrangement_2 &out_arr, CGAL::Tag_false) { void visibility_region(const Point_2 &q, Face_const_handle fh, Arrangement_2 &out_arr) {
std::vector<Point_2> polygon;
visibility_region_impl(q, fh, polygon);
build_arr(polygon, out_arr);
}
/*!
obtain the vertices of visibility into polygon. these vertices can be used to build output arrangement by build_arr().
*/
void visibility_region_impl(const Point_2& q, Face_const_handle fh, std::vector<Point_2>& polygon) {
std::vector<Vertex_const_handle> vertices; //all vertices of the face. std::vector<Vertex_const_handle> vertices; //all vertices of the face.
std::vector<Halfedge_const_handle> edges, active_edges; //edges stores all halfedges of the face; and active_edges stores all halfedges that is currently intersected by the view ray. std::vector<Halfedge_const_handle> edges, active_edges; //edges stores all halfedges of the face; and active_edges stores all halfedges that is currently intersected by the view ray.
//preprocess the face //preprocess the face
input_face(fh, vertices, edges, query); input_face(fh, vertices, edges, q);
//initiation of vision ray //initiation of vision ray
Vector_2 dir; Vector_2 dir;
if (Direction_2(-1, 0) < Direction_2(Vector_2(query, (*vertices.rbegin())->point()))) if (Direction_2(-1, 0) < Direction_2(Vector_2(q, (*vertices.rbegin())->point())))
{ {
dir = Vector_2(1, 0) + Vector_2(query, (*vertices.rbegin())->point()); dir = Vector_2(1, 0) + Vector_2(q, (*vertices.rbegin())->point());
} }
else { else {
dir = Vector_2(0, -1); dir = Vector_2(0, -1);
} }
Ray_2 init_vision_ray(query, dir); Ray_2 init_vision_ray(q, dir);
//initiation of active_edges //initiation of active_edges
typename std::vector<Halfedge_const_handle>::iterator iter1; typename std::vector<Halfedge_const_handle>::iterator iter1;
for (iter1 = edges.begin(); iter1 != edges.end(); iter1++) for (iter1 = edges.begin(); iter1 != edges.end(); iter1++)
@ -215,8 +176,7 @@ public:
insert_halfedge(active_edges, init_vision_ray, *iter1); insert_halfedge(active_edges, init_vision_ray, *iter1);
} }
//angular sweep //angular sweep begins
std::vector<Point_2> polygon;
Ray_2 curr_vision_ray = init_vision_ray; Ray_2 curr_vision_ray = init_vision_ray;
typename std::vector<Vertex_const_handle>::iterator vit = vertices.begin(), begin_it, end_it; typename std::vector<Vertex_const_handle>::iterator vit = vertices.begin(), begin_it, end_it;
Halfedge_const_handle closest_edge; Halfedge_const_handle closest_edge;
@ -227,10 +187,10 @@ public:
{ {
begin_it = vit; begin_it = vit;
end_it = vit; end_it = vit;
curr_vision_ray= Ray_2(query, (*begin_it)->point()); curr_vision_ray= Ray_2(q, (*begin_it)->point());
Direction_2 d1(curr_vision_ray), d2; Direction_2 d1(curr_vision_ray), d2;
do { do {
d2 = Direction_2(Ray_2(query, (*end_it)->point())); d2 = Direction_2(Ray_2(q, (*end_it)->point()));
if (d1 != d2) break; if (d1 != d2) break;
} while (++end_it != vertices.end()); } while (++end_it != vertices.end());
add_edges(begin_it, end_it, active_edges, curr_vision_ray); add_edges(begin_it, end_it, active_edges, curr_vision_ray);
@ -250,27 +210,23 @@ public:
//we don't need to do anything here. //we don't need to do anything here.
} }
else { else {
//add new edge;
//Point_2 p1 = intersection_point(curr_vision_ray, closest_edge);
Point_2 p2 = intersection_point(curr_vision_ray, active_edges[0]); Point_2 p2 = intersection_point(curr_vision_ray, active_edges[0]);
//update_visibility(p1, polygon, out_arr); update_visibility(p2, polygon);
update_visibility(p2, polygon, out_arr);
} }
} }
else { else {
Point_2 right_p, left_p, mid_p; Point_2 right_p, left_p, mid_p;
begin_it = vit; begin_it = vit;
end_it = vit; //all vertices between begin_it and end_it(not included) are collinear with query point. end_it = vit;
curr_vision_ray= Ray_2(query, (*begin_it)->point()); curr_vision_ray= Ray_2(q, (*begin_it)->point());
right_p = intersection_point(curr_vision_ray, active_edges[0]); right_p = intersection_point(curr_vision_ray, active_edges[0]);
Direction_2 d1(curr_vision_ray), d2; Direction_2 d1(curr_vision_ray), d2;
//find end_it such that all vertices between begin_it and end_it(not included) are collinear with query point.
do { do {
d2 = Direction_2(Ray_2(query, (*end_it)->point())); d2 = Direction_2(Ray_2(q, (*end_it)->point()));
if (d1 != d2) break; if (d1 != d2) break;
} while (++end_it != vertices.end()); } while (++end_it != vertices.end());
add_edges(begin_it, end_it, active_edges, curr_vision_ray); add_edges(begin_it, end_it, active_edges, curr_vision_ray);
mid_p = intersection_point(curr_vision_ray, active_edges[0]); mid_p = intersection_point(curr_vision_ray, active_edges[0]);
std::vector<Point_2> collinear_vertices; std::vector<Point_2> collinear_vertices;
Intersection_type i_type = needle(active_edges, curr_vision_ray, collinear_vertices); Intersection_type i_type = needle(active_edges, curr_vision_ray, collinear_vertices);
@ -279,22 +235,20 @@ public:
//todo:this part is not finished. //todo:this part is not finished.
//remove right and collinear; //remove right and collinear;
remove_edges(active_edges, curr_vision_ray); remove_edges(active_edges, curr_vision_ray);
update_visibility(right_p, polygon, out_arr); update_visibility(right_p, polygon);
update_visibility(mid_p, polygon, out_arr); update_visibility(mid_p, polygon);
//todo CGAL::insert_curve(); //todo CGAL::insert_curve();
if (!active_edges.empty()) { if (!active_edges.empty()) {
left_p = intersection_point(curr_vision_ray, active_edges[0]); left_p = intersection_point(curr_vision_ray, active_edges[0]);
update_visibility(left_p, polygon, out_arr); update_visibility(left_p, polygon);
} }
break; break;
case CORNER : case CORNER :
//remove right and collinear; //remove right and collinear;
remove_edges(active_edges, curr_vision_ray); remove_edges(active_edges, curr_vision_ray);
update_visibility(right_p, polygon);
insert_needle(collinear_vertices, polygon);
left_p = intersection_point(curr_vision_ray, active_edges[0]); left_p = intersection_point(curr_vision_ray, active_edges[0]);
update_visibility(right_p, polygon, out_arr);
insert_needle(collinear_vertices, polygon, out_arr);
// update_visibility(mid_p, polygon, out_arr);
// update_visibility(left_p, polygon, out_arr);
polygon.push_back(left_p); polygon.push_back(left_p);
break; break;
case INNER : case INNER :
@ -305,9 +259,8 @@ public:
} }
else { else {
left_p = intersection_point(curr_vision_ray, active_edges[0]); left_p = intersection_point(curr_vision_ray, active_edges[0]);
update_visibility(right_p, polygon, out_arr); update_visibility(right_p, polygon);
insert_needle(collinear_vertices, polygon, out_arr); insert_needle(collinear_vertices, polygon);
// update_visibility(left_p, polygon, out_arr);
polygon.push_back(left_p); polygon.push_back(left_p);
} }
break; break;
@ -315,12 +268,14 @@ public:
} }
vit = end_it; vit = end_it;
} }
if (!is_init_empty) { // if (!is_init_empty) {
CGAL::insert(out_arr, Segment_2(polygon.back(),polygon.front())); // CGAL::insert(out_arr, Segment_2(polygon.back(),polygon.front()));
} // }
} }
bool is_attached() { bool is_attached() {
return attach_tag; return attach_tag;
} }
@ -329,7 +284,6 @@ public:
this->arr = arr; this->arr = arr;
this->attach_tag = true; this->attach_tag = true;
} }
void detach() { void detach() {
attach_tag = false; attach_tag = false;
} }
@ -452,34 +406,6 @@ private:
} }
//sort vertex vh by the angle between vector<p, v> and positive x-ray.
//if the angles are the same, place them in a 'circular' way.
//we do this because the output is not regularized, i.e. 1-d needle is reserved in output.
// void sort_vertex(vector<Vertex_const_handle>& vertices, Vertex_const_handle vh, const Point_2& p, CGAL::Tag_false)
// {
// Ray_2 ray(p, vh->point());
// typename vector<Vertex_const_handle>::iterator first = vertices.begin();
// while (first != vertices.end())
// {
// Ray_2 r(p, (*first)->point());
// Direction_2 d1(r);
// if (ray.direction() < d1)
// break;
// //if angles are the same, then using Isblock() to decide the order of vertices on the view ray.
// if (ray.direction() == d1)
// {
// if (Is_block(vh, ray) && (!Is_block(*first, ray)))
// break;
// if (Is_block(vh, ray) && Is_block(*first, ray) && CGAL::compare_distance_to_point(p, vh->point(), (*first)->point()) == CGAL::SMALLER)
// break;
// if (!Is_block(vh, ray) && !Is_block(*first, ray) && CGAL::compare_distance_to_point(p, vh->point(), (*first)->point()) == CGAL::LARGER)
// break;
// }
// ++first;
// }
// vertices.insert(first, vh);
// }
//traverse the face to get all edges and sort vertices in counter-clockwise order. //traverse the face to get all edges and sort vertices in counter-clockwise order.
void input_face (Face_const_handle fh, void input_face (Face_const_handle fh,
std::vector<Vertex_const_handle>& vertices, std::vector<Vertex_const_handle>& vertices,
@ -506,23 +432,20 @@ private:
//insert new vertice to polygon. before insertion, check if this vertice has been added before. //insert new vertice to polygon. before insertion, check if this vertice has been added before.
void update_visibility(const Point_2 p, std::vector<Point_2>& polygon, Arrangement_2& arr){ void update_visibility(const Point_2 p, std::vector<Point_2>& polygon){
if (polygon.empty()) if (polygon.empty())
polygon.push_back(p); polygon.push_back(p);
else else
{ {
if (polygon.back() != p){ if (polygon.back() != p) {
CGAL::insert(arr, Segment_2(polygon.back(), p));
polygon.push_back(p); polygon.push_back(p);
} }
} }
} }
void insert_needle(const std::vector<Point_2>& points, std::vector<Point_2>& polygon, Arrangement_2 &arr){ void insert_needle(const std::vector<Point_2>& points, std::vector<Point_2>& polygon){
if (points.size() > 1) { for (int i = 0; i != points.size(); i++) {
for (int i = 0; i != points.size()-1; i++) { update_visibility(points[i], polygon);
CGAL::insert(arr, Segment_2(points[i], points[i+1]));
}
} }
} }
@ -579,8 +502,6 @@ private:
eit++; eit++;
} }
} }
} }
bool is_on_ray(const Ray_2& r, const Point_2& p) { bool is_on_ray(const Ray_2& r, const Point_2& p) {
@ -650,6 +571,11 @@ private:
} while (++curr != edges.end()); } while (++curr != edges.end());
return UNBOUNDED; return UNBOUNDED;
} }
void build_arr(const std::vector<Point_2>& polygon, Arrangement& arr ) {
}
//debug //debug
void print_edges(std::vector<Halfedge_const_handle>& edges){ void print_edges(std::vector<Halfedge_const_handle>& edges){
for (int i = 0; i != edges.size(); i++) { for (int i = 0; i != edges.size(); i++) {