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#include <2geom/sweep-bounds.h>
#include <algorithm>
namespace Geom {
struct Event {
double x;
unsigned ix;
bool closing;
Event(double pos, unsigned i, bool c) : x(pos), ix(i), closing(c) {}
// Lexicographic ordering by x then closing
bool operator<(Event const &other) const {
if(x < other.x) return true;
if(x > other.x) return false;
return closing < other.closing;
}
bool operator==(Event const &other) const {
return other.x == x && other.ix == ix && other.closing == closing;
}
};
std::vector<std::vector<unsigned> > fake_cull(unsigned a, unsigned b);
/**
* \brief Make a list of pairs of self intersections in a list of Rects.
*
* \param rs: vector of Rect.
* \param d: dimension to sweep along
*
* [(A = rs[i], B = rs[j]) for i,J in enumerate(pairs) for j in J]
* then A.left <= B.left
*/
std::vector<std::vector<unsigned> > sweep_bounds(std::vector<Rect> rs, Dim2 d) {
std::vector<Event> events; events.reserve(rs.size()*2);
std::vector<std::vector<unsigned> > pairs(rs.size());
for(unsigned i = 0; i < rs.size(); i++) {
events.emplace_back(rs[i][d].min(), i, false);
events.emplace_back(rs[i][d].max(), i, true);
}
std::sort(events.begin(), events.end());
std::vector<unsigned> open;
for(auto & event : events) {
unsigned ix = event.ix;
if(event.closing) {
std::vector<unsigned>::iterator iter = std::find(open.begin(), open.end(), ix);
//if(iter != open.end())
open.erase(iter);
} else {
for(unsigned int jx : open) {
if(rs[jx][1-d].intersects(rs[ix][1-d])) {
pairs[jx].push_back(ix);
}
}
open.push_back(ix);
}
}
return pairs;
}
/**
* \brief Make a list of pairs of red-blue intersections between two lists of Rects.
*
* \param a: vector of Rect.
* \param b: vector of Rect.
* \param d: dimension to scan along
*
* [(A = rs[i], B = rs[j]) for i,J in enumerate(pairs) for j in J]
* then A.left <= B.left, A in a, B in b
*/
std::vector<std::vector<unsigned> > sweep_bounds(std::vector<Rect> a, std::vector<Rect> b, Dim2 d) {
std::vector<std::vector<unsigned> > pairs(a.size());
if(a.empty() || b.empty()) return pairs;
std::vector<Event> events[2];
events[0].reserve(a.size()*2);
events[1].reserve(b.size()*2);
for(unsigned n = 0; n < 2; n++) {
unsigned sz = n ? b.size() : a.size();
events[n].reserve(sz*2);
for(unsigned i = 0; i < sz; i++) {
Rect r = n ? b[i] : a[i];
events[n].emplace_back(r[d].min(), i, false);
events[n].emplace_back(r[d].max(), i, true);
}
std::sort(events[n].begin(), events[n].end());
}
std::vector<unsigned> open[2];
bool n = events[1].front() < events[0].front();
{// As elegant as putting the initialiser in the for was, it upsets some legacy compilers (MS VS C++)
unsigned i[] = {0,0};
for(; i[n] < events[n].size();) {
unsigned ix = events[n][i[n]].ix;
bool closing = events[n][i[n]].closing;
//std::cout << n << "[" << ix << "] - " << (closing ? "closer" : "opener") << "\n";
if(closing) {
open[n].erase(std::find(open[n].begin(), open[n].end(), ix));
} else {
if(n) {
//n = 1
//opening a B, add to all open a
for(unsigned int jx : open[0]) {
if(a[jx][1-d].intersects(b[ix][1-d])) {
pairs[jx].push_back(ix);
}
}
} else {
//n = 0
//opening an A, add all open b
for(unsigned int jx : open[1]) {
if(b[jx][1-d].intersects(a[ix][1-d])) {
pairs[ix].push_back(jx);
}
}
}
open[n].push_back(ix);
}
i[n]++;
if(i[n]>=events[n].size()) {break;}
n = (events[!n][i[!n]] < events[n][i[n]]) ? !n : n;
}}
return pairs;
}
//Fake cull, until the switch to the real sweep is made.
std::vector<std::vector<unsigned> > fake_cull(unsigned a, unsigned b) {
std::vector<std::vector<unsigned> > ret;
std::vector<unsigned> all;
for(unsigned j = 0; j < b; j++)
all.push_back(j);
for(unsigned i = 0; i < a; i++)
ret.push_back(all);
return ret;
}
}
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
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