118 lines
2.4 KiB
C++
118 lines
2.4 KiB
C++
#include "Polygon.h"
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#include <math.h>
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double Polygon::area() const {
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double d = 0.0;
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for(const_iterator it = begin(); it != end(); it++) {
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const_iterator it2 = it+1;
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if(it2 == end()) it2 = begin();
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d += (it2->getX()+it->getX())*(it2->getY()-it->getY());
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}
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return fabs(d/2);
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}
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double Polygon::perimeter() const {
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double d = 0.0;
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for(const_iterator it = begin(); it != end(); it++) {
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const_iterator it2 = it+1;
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if(it2 == end()) it2 = begin();
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d += it->distance(*it2);
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}
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return d;
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}
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int Polygon::quadrant(const Vertex &v) const {
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if(v.getX() > 0 && v.getY() >= 0) return 1;
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if(v.getX() >= 0 && v.getY() < 0) return 2;
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if(v.getX() < 0 && v.getY() <= 0) return 3;
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if(v.getX() <= 0 && v.getY() > 0) return 4;
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return 0;
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}
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bool Polygon::contains(const Vertex &v) const {
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const Line d1(-1, -1, 1, 1);
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const Line d2(-1, 1, 1, -1);
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int d = 0;
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int q, ql, q2;
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Line l;
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Vertex v2;
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if(empty()) return false;
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v2 = back() - v;
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q = quadrant(v2);
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if(q == 0) return true;
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for(const_iterator it = begin(); it != end(); it++) {
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ql = q;
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v2 = *it - v;
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q = quadrant(v2);
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if(q == 0) return true;
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switch(q-ql) {
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case 0:
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break;
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case 1:
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case -3:
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d++;
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break;
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case 3:
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case -1:
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d--;
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break;
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default:
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l.setVertex1(((it == begin()) ? back() : *(it-1)) - v);
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l.setVertex2(v2);
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if(q == 1 || q == 3) {
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if(!(l.intersects(d2, &v2) & INTERSECTION_LINE)) return false;
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q2 = quadrant(v2);
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if(q2 == 0) return true;
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if((q == 1 && q2 == 2) || (q == 3 && q2 == 4)) d -= 2;
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else d += 2;
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}
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else {
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if(!(l.intersects(d1, &v2) & INTERSECTION_LINE)) return false;
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q2 = quadrant(v2);
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if(q2 == 0) return true;
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if((q == 2 && q2 == 3) || (q == 4 && q2 == 1)) d -= 2;
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else d += 2;
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}
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}
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}
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return (d != 0);
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}
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bool Polygon::intersects(const Line &l) const {
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Line line;
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for(Polygon::const_iterator it = begin(); it != end(); it++) {
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Polygon::const_iterator it2 = it+1;
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if(it2 == end()) it2 = begin();
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line.setVertex1(*it);
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line.setVertex2(*it2);
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if(l.intersects(line, NULL) == INTERSECTION_SEGMENT_SEGMENT)
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return true;
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}
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return false;
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}
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