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67
src/Tour.cpp
67
src/Tour.cpp
@ -52,7 +52,7 @@ void Tour::draw(QGraphicsScene *scene) const {
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return;
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Node *node = m_startNode;
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do {
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do{
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node->point.draw(scene);
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node->point.drawTo(node->next->point, scene);
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node = node->next;
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@ -116,71 +116,6 @@ void Tour::insertNearest(Point p) {
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nearest->next = newNode;
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}
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enum class Orientation { COLLINEAR, CLOCKWISE, COUNTER_CLOCKWISE };
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// I'm not going to pretend that I came up with this on my own.
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// The description for the algorithms is found both in the
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// linear algebra course, and on this wiki
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// https://en.wikipedia.org/w/index.php?title=Line-line_intersection&oldid=1229564037
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// Calculate the calcOrientation of the triplet (p, q, r)
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inline Orientation calcOrientation(const Point &p, const Point &q, const Point &r) {
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int val = (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
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if (val == 0)
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return Orientation::COLLINEAR;
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return (val > 0) ? Orientation::CLOCKWISE : Orientation::COUNTER_CLOCKWISE;
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}
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// True if q lies on the segment p-r
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inline bool isOnSegment(const Point &p, const Point &q, const Point &r) {
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return (q.x <= std::max(p.x, r.x) && q.x >= std::min(p.x, r.x) &&
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q.y <= std::max(p.y, r.y) && q.y >= std::min(p.y, r.y));
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}
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// Check if the two line segments p1q1 and p2q2 intersect
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bool doesPointsIntersect(const Point &p1, const Point &q1, const Point &p2,
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const Point &q2) {
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Orientation o1 = calcOrientation(p1, q1, p2);
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Orientation o2 = calcOrientation(p1, q1, q2);
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Orientation o3 = calcOrientation(p2, q2, p1);
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Orientation o4 = calcOrientation(p2, q2, q1);
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// General case: line segments intersect if they have different orientations
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if (o1 != o2 && o3 != o4)
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return true;
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// Special cases
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// p1, q1, p2 are collinear and p2 lies on segment p1q1
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if (o1 == Orientation::COLLINEAR && isOnSegment(p1, p2, q1))
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return true;
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// p1, q1, q2 are collinear and q2 lies on segment p1q1
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if (o2 == Orientation::COLLINEAR && isOnSegment(p1, q2, q1))
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return true;
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// p2, q2, p1 are collinear and p1 lies on segment p2q2
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if (o3 == Orientation::COLLINEAR && isOnSegment(p2, p1, q2))
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return true;
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// p2, q2, q1 are collinear and q1 lies on segment p2q2
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if (o4 == Orientation::COLLINEAR && isOnSegment(p2, q1, q2))
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return true;
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return false;
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}
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bool Tour::pointsCross(Point &p1, Point &p2) {
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if (m_startNode == nullptr || m_startNode->next == m_startNode)
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return false;
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Node *n1 = m_startNode, *n2 = m_startNode->next;
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do {
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Point &q1 = n1->point, &q2 = n2->point;
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if (doesPointsIntersect(p1, p2, q1, q2))
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return true;
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n1 = n2;
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n2 = n2->next;
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} while (n1 != m_startNode);
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return false;
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}
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void Tour::insertSmallest(Point p) {
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if (m_startNode == nullptr) {
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m_startNode = new Node(p);
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@ -27,8 +27,6 @@ public:
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private:
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Node* m_startNode;
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bool pointsCross(Point &p1, Point &p2);
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};
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#endif // TOUR_H
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