PrusaSlicer-NonPlainar/xs/src/Geometry.cpp

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#include "Geometry.hpp"
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#include "clipper.hpp"
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#include <algorithm>
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#include <map>
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namespace Slic3r { namespace Geometry {
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static bool
sort_points (Point a, Point b)
{
return (a.x < b.x) || (a.x == b.x && a.y < b.y);
}
/* This implementation is based on Steffen Mueller's work for
the Perl module Math::ConvexHull::MonotoneChain (available
on CPAN under the GPL terms) */
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void
convex_hull(Points points, Polygon &hull)
{
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assert(points.size() >= 3);
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// sort input points
std::sort(points.begin(), points.end(), sort_points);
typedef const Point* PointPtr;
PointPtr* out_hull = (PointPtr*)malloc(points.size()*2*sizeof(PointPtr));
/* lower hull */
size_t k = 0;
for (Points::const_iterator it = points.begin(); it != points.end(); ++it) {
while (k >= 2 && it->ccw(out_hull[k-2], out_hull[k-1]) <= 0) --k;
Point pz = *&*it;
out_hull[k++] = &*it;
}
/* upper hull */
size_t t = k+1;
for (Points::const_iterator it = points.end() - 2; it != points.begin(); --it) {
while (k >= t && it->ccw(out_hull[k-2], out_hull[k-1]) <= 0) --k;
out_hull[k++] = &*it;
}
// we assume hull is empty
hull.points.reserve(k);
for (size_t i = 0; i < k; ++i) {
hull.points.push_back(*(out_hull[i]));
}
// not sure why this happens randomly
if (hull.points.front().coincides_with(hull.points.back()))
hull.points.pop_back();
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free(out_hull);
}
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/* accepts an arrayref of points and returns a list of indices
according to a nearest-neighbor walk */
void
chained_path(Points &points, std::vector<Points::size_type> &retval, Point start_near)
{
PointPtrs my_points;
std::map<Point*,Points::size_type> indices;
my_points.reserve(points.size());
for (Points::iterator it = points.begin(); it != points.end(); ++it) {
my_points.push_back(&*it);
indices[&*it] = it - points.begin();
}
retval.reserve(points.size());
while (!my_points.empty()) {
Points::size_type idx = start_near.nearest_point_index(my_points);
start_near = *my_points[idx];
retval.push_back(indices[ my_points[idx] ]);
my_points.erase(my_points.begin() + idx);
}
}
void
chained_path(Points &points, std::vector<Points::size_type> &retval)
{
if (points.empty()) return; // can't call front() on empty vector
chained_path(points, retval, points.front());
}
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/* retval and items must be different containers */
template<class T>
void
chained_path_items(Points &points, T &items, T &retval)
{
std::vector<Points::size_type> indices;
chained_path(points, indices);
for (std::vector<Points::size_type>::const_iterator it = indices.begin(); it != indices.end(); ++it)
retval.push_back(items[*it]);
}
template void chained_path_items(Points &points, ClipperLib::PolyNodes &items, ClipperLib::PolyNodes &retval);
} }