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2 changed files with 1 additions and 68 deletions

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@ -116,71 +116,6 @@ void Tour::insertNearest(Point p) {
nearest->next = newNode; nearest->next = newNode;
} }
enum class Orientation { COLLINEAR, CLOCKWISE, COUNTER_CLOCKWISE };
// I'm not going to pretend that I came up with this on my own.
// The description for the algorithms is found both in the
// linear algebra course, and on this wiki
// https://en.wikipedia.org/w/index.php?title=Line-line_intersection&oldid=1229564037
// Calculate the calcOrientation of the triplet (p, q, r)
inline Orientation calcOrientation(const Point &p, const Point &q, const Point &r) {
int val = (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
if (val == 0)
return Orientation::COLLINEAR;
return (val > 0) ? Orientation::CLOCKWISE : Orientation::COUNTER_CLOCKWISE;
}
// True if q lies on the segment p-r
inline bool isOnSegment(const Point &p, const Point &q, const Point &r) {
return (q.x <= std::max(p.x, r.x) && q.x >= std::min(p.x, r.x) &&
q.y <= std::max(p.y, r.y) && q.y >= std::min(p.y, r.y));
}
// Check if the two line segments p1q1 and p2q2 intersect
bool doesPointsIntersect(const Point &p1, const Point &q1, const Point &p2,
const Point &q2) {
Orientation o1 = calcOrientation(p1, q1, p2);
Orientation o2 = calcOrientation(p1, q1, q2);
Orientation o3 = calcOrientation(p2, q2, p1);
Orientation o4 = calcOrientation(p2, q2, q1);
// General case: line segments intersect if they have different orientations
if (o1 != o2 && o3 != o4)
return true;
// Special cases
// p1, q1, p2 are collinear and p2 lies on segment p1q1
if (o1 == Orientation::COLLINEAR && isOnSegment(p1, p2, q1))
return true;
// p1, q1, q2 are collinear and q2 lies on segment p1q1
if (o2 == Orientation::COLLINEAR && isOnSegment(p1, q2, q1))
return true;
// p2, q2, p1 are collinear and p1 lies on segment p2q2
if (o3 == Orientation::COLLINEAR && isOnSegment(p2, p1, q2))
return true;
// p2, q2, q1 are collinear and q1 lies on segment p2q2
if (o4 == Orientation::COLLINEAR && isOnSegment(p2, q1, q2))
return true;
return false;
}
bool Tour::pointsCross(Point &p1, Point &p2) {
if (m_startNode == nullptr || m_startNode->next == m_startNode)
return false;
Node *n1 = m_startNode, *n2 = m_startNode->next;
do {
Point &q1 = n1->point, &q2 = n2->point;
if (doesPointsIntersect(p1, p2, q1, q2))
return true;
n1 = n2;
n2 = n2->next;
} while (n1 != m_startNode);
return false;
}
void Tour::insertSmallest(Point p) { void Tour::insertSmallest(Point p) {
if (m_startNode == nullptr) { if (m_startNode == nullptr) {
m_startNode = new Node(p); m_startNode = new Node(p);

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@ -27,8 +27,6 @@ public:
private: private:
Node* m_startNode; Node* m_startNode;
bool pointsCross(Point &p1, Point &p2);
}; };
#endif // TOUR_H #endif // TOUR_H