126 lines
2.8 KiB
C++
126 lines
2.8 KiB
C++
#ifndef POLYGON2_H
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#define POLYGON2_H
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#include "Point2.h"
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#include <vector>
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#include "Line2.h"
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#include "BBox2.h"
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static bool polygonContainsPoint(const std::vector<Point2>& poly, const Point2 p);
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class Polygon2 {
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std::vector<Point2> pts;
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public:
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void add(const Point2 p) {
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pts.push_back(p);
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}
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std::vector<Point2>::iterator begin() {return pts.begin();}
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std::vector<Point2>::iterator end() {return pts.end();}
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std::vector<Point2>::const_iterator begin() const {return pts.begin();}
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std::vector<Point2>::const_iterator end() const {return pts.end();}
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std::vector<Point2>& getVector() {return pts;}
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Point2& operator [] (const size_t idx) {
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return pts[idx];
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}
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/** get polygon as list of lines */
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std::vector<Line2> getLines() const {
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std::vector<Line2> res;
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for (size_t i = 0; i < pts.size(); ++i) {
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const Point2 p1 = pts[(i+0)];
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const Point2 p2 = pts[(i+1)%pts.size()];
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res.push_back(Line2(p1, p2));
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}
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return res;
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}
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struct CutRes {
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Point2 p;
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size_t i1,i2; // line, given by two points, within this poly
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size_t j1,j2; // line, given by two points, within other, given poly
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CutRes(Point2 p, size_t i1, size_t i2, size_t j1, size_t j2) : p(p), i1(i1), i2(i2), j1(j1), j2(j2) {;}
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};
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BBox2 getBBox() const {
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BBox2 bb;
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for (const Point2 p : pts) {bb.add(p);}
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return bb;
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}
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bool contains(const Point2 p) const {
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return polygonContainsPoint(pts, p);
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}
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std::vector<CutRes> getIntersections(const Polygon2& o, bool limit = true) const {
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std::vector<CutRes> res;
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for (size_t i = 0; i < pts.size(); ++i) {
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const size_t i1 = (i+0);
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const size_t i2 = (i+1) % pts.size();
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const Line2 l1(pts[i1], pts[i2]);
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for (size_t j = 0; j < o.pts.size(); ++j) {
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const size_t j1 = (j+0);
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const size_t j2 = (j+1) % o.pts.size();
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const Line2 l2(o.pts[j1], o.pts[j2]);
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Point2 p;
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//if (l1.getSegmentIntersection(l2, p)) {
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if (intersects(l1, l2, limit, p)) {
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res.push_back(CutRes(p, i1,i2, j1,j2));
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}
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}
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}
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return res;
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}
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};
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/** does the given polygon (list of points) contain the given point? */
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static bool polygonContainsPoint(const std::vector<Point2>& poly, const Point2 p) {
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// https://en.wikipedia.org/wiki/Winding_number
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// http://geomalgorithms.com/a03-_inclusion.html
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// BBox2 bb
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// bb.grow(Point2(0.001, 0.001));
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// if (!bb.contains(p)) {return false;}
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double sum = 0;
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for (size_t i = 0; i < poly.size(); ++i) {
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const Point2 p1 = poly[i];
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const Point2 p2 = poly[(i+1)%poly.size()];
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const Point2 d1 = (p1-p).normalized();
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const Point2 d2 = (p2-p).normalized();
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sum += std::acos(dot(d1, d2));
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}
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// normalize (x = number of windings)
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const double x = sum / M_PI / 2;
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// only look at the fractional part
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//const double y = x - std::floor(x);
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return std::abs(x) >= 0.975;// && (std::abs(y) >= 0.9 || std::abs(y) < 0.1);
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}
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#endif // POLYGON2_H
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