mirror of https://github.com/CGAL/cgal
introducing intersection info for segment_2-segment_2
Intersect_2 uses combinarics information from Do_intersect_2
This commit is contained in:
Sébastien Loriot
parent
aa1b53a4a1
commit
e19ddaceb4
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@ -28,62 +28,137 @@
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#include <CGAL/Uncertain.h>
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#include <CGAL/Intersection_traits_2.h>
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#include <functional>
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namespace CGAL {
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namespace Intersections {
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namespace internal {
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struct S2S2_inter_info
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{
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bool inter = false;
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bool dim = 0;
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std::array<int, 2> pt_ids = {-1,-1};
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S2S2_inter_info(bool inter)
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: inter(inter)
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{}
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S2S2_inter_info(int id)
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: inter(true)
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{
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pt_ids[0]=id;
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}
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S2S2_inter_info(int id1,int id2, int dim)
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: inter(true)
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, dim(dim)
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{
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pt_ids[0]=id1;
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pt_ids[1]=id2;
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}
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};
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template <class K>
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inline bool
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inline S2S2_inter_info
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do_intersect(const typename K::Segment_2 &seg1, const typename K::Segment_2 &seg2);
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// lexicographic order of points p1 < p3 < p2 < p4, with segments (p1,p2) and (p3,p4)
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template <class K>
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bool seg_seg_do_intersect_crossing(
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const typename K::Point_2 &p1, const typename K::Point_2 &p2,
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const typename K::Point_2 &p3, const typename K::Point_2 &p4,
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const K& k)
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S2S2_inter_info
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seg_seg_do_intersect_crossing(
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const typename K::Point_2& p1, const typename K::Point_2& p2,
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const typename K::Point_2& p3, const typename K::Point_2& p4,
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int i1, int i2, int i3, int i4,
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const K& k, bool extra_test)
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{
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switch (make_certain(k.orientation_2_object()(p1,p2,p3))) {
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case LEFT_TURN:
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return ! (k.orientation_2_object()(p3,p4,p2) == RIGHT_TURN); // right_turn(p3,p4,p2);
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{
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switch (k.orientation_2_object()(p3,p4,p2))
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{
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case COLLINEAR:
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return S2S2_inter_info(i2);
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case RIGHT_TURN:
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return S2S2_inter_info(false);
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case LEFT_TURN:
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return S2S2_inter_info(true);
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}
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}
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case RIGHT_TURN:
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return ! (k.orientation_2_object()(p3,p4,p2) == LEFT_TURN); //left_turn(p3,p4,p2);
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{
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switch (k.orientation_2_object()(p3,p4,p2))
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{
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case COLLINEAR:
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return S2S2_inter_info(i2);
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case RIGHT_TURN:
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return S2S2_inter_info(true);
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case LEFT_TURN:
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return S2S2_inter_info(false);
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}
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}
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case COLLINEAR:
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return true;
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if (extra_test && k.collinear_2_object()(p3,p4,p2))
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return S2S2_inter_info(i3, i2, 1);
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return S2S2_inter_info(i3);
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}
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CGAL_kernel_assertion(false);
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return false;
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return S2S2_inter_info(false);
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}
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// lexicographic order of points p1 < p3 < p4 < p2, with segments (p1,p2) and (p3,p4)
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template <class K>
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S2S2_inter_info
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seg_seg_do_intersect_contained(
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const typename K::Point_2& p1, const typename K::Point_2& p2,
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const typename K::Point_2& p3, const typename K::Point_2& p4,
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int i1, int i2, int i3, int i4,
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const K& k, bool extra_test)
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{
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switch (make_certain(k.orientation_2_object()(p1,p2,p3))) {
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case LEFT_TURN:
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{
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switch (k.orientation_2_object()(p1,p2,p4))
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{
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case COLLINEAR:
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return S2S2_inter_info(i4);
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case RIGHT_TURN:
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return S2S2_inter_info(true);
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case LEFT_TURN:
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return S2S2_inter_info(false);
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}
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}
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case RIGHT_TURN:
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{
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switch (k.orientation_2_object()(p1,p2,p4))
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{
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case COLLINEAR:
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return S2S2_inter_info(i4);
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case RIGHT_TURN:
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return S2S2_inter_info(false);
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case LEFT_TURN:
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return S2S2_inter_info(true);
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}
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}
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case COLLINEAR:
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if (extra_test && k.collinear_2_object()(p3,p4,p2))
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return S2S2_inter_info(i3, i4, 1);
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return S2S2_inter_info(i3);
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}
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CGAL_kernel_assertion(false);
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return S2S2_inter_info(false);
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}
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template <class K>
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bool seg_seg_do_intersect_contained(
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const typename K::Point_2 &p1, const typename K::Point_2 &p2,
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const typename K::Point_2 &p3, const typename K::Point_2 &p4,
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const K& k)
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{
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switch (make_certain(k.orientation_2_object()(p1,p2,p3))) {
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case LEFT_TURN:
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return ! (k.orientation_2_object()(p1,p2,p4) == LEFT_TURN); // left_turn(p1,p2,p4);
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case RIGHT_TURN:
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return ! (k.orientation_2_object()(p1,p2,p4) == RIGHT_TURN); // right_turn(p1,p2,p4);
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case COLLINEAR:
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return true;
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}
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CGAL_kernel_assertion(false);
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return false;
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}
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template <class K>
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bool
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do_intersect(const typename K::Segment_2 &seg1,
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const typename K::Segment_2 &seg2,
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const K& k)
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S2S2_inter_info
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do_intersect_with_info(const typename K::Segment_2 &seg1,
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const typename K::Segment_2 &seg2,
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const K& k, bool extra_test)
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{
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typename K::Less_xy_2 less_xy;
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@ -105,50 +180,82 @@ do_intersect(const typename K::Segment_2 &seg1,
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// first try to filter using the bbox of the segments
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if (less_xy(A2,B1)
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|| less_xy(B2,A1))
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return false;
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return S2S2_inter_info(false);
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switch(make_certain(compare_xy(A1,B1))) {
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case SMALLER:
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switch(make_certain(compare_xy(A2,B1))) {
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case SMALLER:
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return false;
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return S2S2_inter_info(false);
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case EQUAL:
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return true;
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return S2S2_inter_info(A2_id, B1_id+2, 0);
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default: // LARGER
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switch(make_certain(compare_xy(A2,B2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(A1,A2,B1,B2, k);
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return seg_seg_do_intersect_crossing(A1,A2,B1,B2, A1_id,A2_id,B1_id+2,B2_id+2, k, extra_test);
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case EQUAL:
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return true;
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// A1 < B1 < B2 = A1
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if (extra_test && k.collinear_2_object()(A1, A2, B1))
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return S2S2_inter_info(B1_id+2, B2_id+2, 1); // TODO: A2==B2 too but bit is not set
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return S2S2_inter_info(A2_id, B2_id+2, 0);
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default: // LARGER
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return seg_seg_do_intersect_contained(A1,A2,B1,B2, k);
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return seg_seg_do_intersect_contained(A1,A2,B1,B2, A1_id,A2_id,B1_id+2,B2_id+2, k, extra_test);
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}
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}
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case EQUAL:
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return true;
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if (extra_test)
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{
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switch(make_certain(compare_xy(A2,B2))) {
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case SMALLER:
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// A1 = B1 < A2 < B2
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if (k.collinear_2_object()(A1,A2,B2))
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return S2S2_inter_info(A1_id, A2_id, 1); // TODO A1==B1 too but bit is not set
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break;
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case EQUAL:
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// A1 = B1 < A2 = B2
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return S2S2_inter_info(A1_id, A2_id, 1); // TODO A1==B1 and A2==B2 too but bits are not set
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default: // LARGER
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// A1 = B1 < B2 < A2
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if (k.collinear_2_object()(A1,A2,B2))
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return S2S2_inter_info(B1_id+2, B2_id+2, 1); // TODO A1==B1 too but bit is not set
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}
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}
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return S2S2_inter_info(A1_id, B1_id+2, 0);
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default: // LARGER
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switch(make_certain(compare_xy(B2,A1))) {
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case SMALLER:
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return false;
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return S2S2_inter_info(false);
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case EQUAL:
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return true;
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return S2S2_inter_info(A1_id, B2_id+2, 0);
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default: // LARGER
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switch(make_certain(compare_xy(B2,A2))) {
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case SMALLER:
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return seg_seg_do_intersect_crossing(B1,B2,A1,A2, k);
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return seg_seg_do_intersect_crossing(B1,B2,A1,A2, B1_id+2,B2_id+2,A1_id,A2_id, k, extra_test);
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case EQUAL:
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return true;
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// B1 < A1 < A2 = B2
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if (extra_test && k.collinear_2_object()(B1, A1, B2))
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return S2S2_inter_info(A1_id, A2_id, 1); // TODO A2==B2 too but bit not set
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return S2S2_inter_info(A2_id, B2_id+2, 0);
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default: // LARGER
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return seg_seg_do_intersect_contained(B1,B2,A1,A2, k);
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return seg_seg_do_intersect_contained(B1,B2,A1,A2, B1_id+2,B2_id+2,A1_id,A2_id, k, extra_test);
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}
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}
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}
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CGAL_kernel_assertion(false);
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return false;
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return S2S2_inter_info(false);
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}
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template <class K>
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bool
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do_intersect(const typename K::Segment_2 &seg1,
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const typename K::Segment_2 &seg2,
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const K& k)
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{
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return do_intersect_with_info(seg1, seg2, k, false).inter;
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}
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template <class K>
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class Segment_2_Segment_2_pair {
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public:
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@ -175,10 +282,44 @@ Segment_2_Segment_2_pair<K>::intersection_type() const
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typename K::Construct_vector_2 construct_vector;
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if (_result!=UNKNOWN)
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return _result;
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if (!internal::do_intersect(*_seg1, *_seg2, K())) {
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S2S2_inter_info inter_info = do_intersect_with_info(*_seg1, *_seg2, K(), true);
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if (!inter_info.inter) {
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_result = NO_INTERSECTION;
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return _result;
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}
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// check if intersection is a segment
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if (inter_info.dim==1)
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{
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_result=SEGMENT;
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// TODO: avoid reference_wrapper?
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std::vector< std::reference_wrapper<const typename K::Point_2> > pts;
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for (int i=0;i<2;++i)
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if (inter_info.pt_ids[i]>1)
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pts.push_back( std::cref(_seg2->point(inter_info.pt_ids[i]-2)) );
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else
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pts.push_back( std::cref(_seg1->point(inter_info.pt_ids[i])) );
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CGAL_assertion(pts.size()==2);
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_intersection_point = pts[0];
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_other_point = pts[1];
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return _result;
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}
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// check if intersection is an input endpoint
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if (inter_info.pt_ids[0]>=0)
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{
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_result = POINT;
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if (inter_info.pt_ids[0]>1)
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_intersection_point = _seg2->point(inter_info.pt_ids[0]-2);
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else
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_intersection_point = _seg1->point(inter_info.pt_ids[0]);
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return _result;
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}
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// TODO: use closed formula for 2 intersecting segments
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typename K::Line_2 const &l1 = _seg1->supporting_line();
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typename K::Line_2 const &l2 = _seg2->supporting_line();
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Line_2_Line_2_pair<K> linepair(&l1, &l2);
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