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PrusaSlicer/src/libslic3r/ElephantFootCompensation.cpp
bubnikv fe4b65e305 Improvement of the Elephant foot compensation: 
Using a positive curvature estimate to control the strength
of the Elephant foot compensation shall work similarly to
the previous implementation while avoiding pinching off
tiny pieces from the contour.
2019-11-15 16:20:01 +01:00

610 lines
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#include "clipper/clipper_z.hpp"
#include "libslic3r.h"
#include "ClipperUtils.hpp"
#include "EdgeGrid.hpp"
#include "ExPolygon.hpp"
#include "ElephantFootCompensation.hpp"
#include "Flow.hpp"
#include "Geometry.hpp"
#include "SVG.hpp"
#include "Utils.hpp"
#include <cmath>
#include <cassert>
// #define CONTOUR_DISTANCE_DEBUG_SVG
namespace Slic3r {
struct ResampledPoint {
ResampledPoint(size_t idx_src, bool interpolated, double curve_parameter) : idx_src(idx_src), interpolated(interpolated), curve_parameter(curve_parameter) {}
size_t idx_src;
// Is this point interpolated or initial?
bool interpolated;
// Euclidean distance along the curve from the 0th point.
double curve_parameter;
};
// Distance calculated using SDF (Shape Diameter Function).
// The distance is calculated by casting a fan of rays and measuring the intersection distance.
// Thus the calculation is relatively slow. For the Elephant foot compensation purpose, this distance metric does not avoid
// pinching off small pieces of a contour, thus this function has been superseded by contour_distance2().
std::vector<float> contour_distance(const EdgeGrid::Grid &grid, const size_t idx_contour, const Slic3r::Points &contour, const std::vector<ResampledPoint> &resampled_point_parameters, double search_radius)
{
assert(! contour.empty());
assert(contour.size() >= 2);
std::vector<float> out;
if (contour.size() > 2)
{
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
static int iRun = 0;
++ iRun;
BoundingBox bbox = get_extents(contour);
bbox.merge(grid.bbox());
ExPolygon expoly_grid;
expoly_grid.contour = Polygon(*grid.contours().front());
for (size_t i = 1; i < grid.contours().size(); ++ i)
expoly_grid.holes.emplace_back(Polygon(*grid.contours()[i]));
#endif
struct Visitor {
Visitor(const EdgeGrid::Grid &grid, const size_t idx_contour, const std::vector<ResampledPoint> &resampled_point_parameters, double dist_same_contour_reject) :
grid(grid), idx_contour(idx_contour), resampled_point_parameters(resampled_point_parameters), dist_same_contour_reject(dist_same_contour_reject) {}
void init(const size_t aidx_point_start, const Point &apt_start, Vec2d dir, const double radius) {
this->idx_point_start = aidx_point_start;
this->pt = apt_start.cast<double>() + SCALED_EPSILON * dir;
dir *= radius;
this->pt_start = this->pt.cast<coord_t>();
// Trim the vector by the grid's bounding box.
const BoundingBox &bbox = this->grid.bbox();
double t = 1.;
for (size_t axis = 0; axis < 2; ++ axis) {
double dx = std::abs(dir(axis));
if (dx >= EPSILON) {
double tedge = (dir(axis) > 0) ? (double(bbox.max(axis)) - SCALED_EPSILON - this->pt(axis)) : (this->pt(axis) - double(bbox.min(axis)) - SCALED_EPSILON);
if (tedge < dx)
t = std::min(t, tedge / dx);
}
}
this->dir = dir;
if (t < 1.)
dir *= t;
this->pt_end = (this->pt + dir).cast<coord_t>();
this->t_min = 1.;
assert(this->grid.bbox().contains(this->pt_start) && this->grid.bbox().contains(this->pt_end));
}
bool operator()(coord_t iy, coord_t ix) {
// Called with a row and colum of the grid cell, which is intersected by a line.
auto cell_data_range = this->grid.cell_data_range(iy, ix);
bool valid = true;
for (auto it_contour_and_segment = cell_data_range.first; it_contour_and_segment != cell_data_range.second; ++ it_contour_and_segment) {
// End points of the line segment and their vector.
auto segment = this->grid.segment(*it_contour_and_segment);
if (Geometry::segments_intersect(segment.first, segment.second, this->pt_start, this->pt_end)) {
// The two segments intersect. Calculate the intersection.
Vec2d pt2 = segment.first.cast<double>();
Vec2d dir2 = segment.second.cast<double>() - pt2;
Vec2d vptpt2 = pt - pt2;
double denom = dir(0) * dir2(1) - dir2(0) * dir(1);
if (std::abs(denom) >= EPSILON) {
double t = cross2(dir2, vptpt2) / denom;
assert(t > - EPSILON && t < 1. + EPSILON);
bool this_valid = true;
if (it_contour_and_segment->first == idx_contour) {
// The intersected segment originates from the same contour as the starting point.
// Reject the intersection if it is close to the starting point.
// Find the start and end points of this segment
double param_lo = resampled_point_parameters[idx_point_start].curve_parameter;
double param_hi;
double param_end = resampled_point_parameters.back().curve_parameter;
{
const Slic3r::Points &ipts = *grid.contours()[it_contour_and_segment->first];
size_t ipt = it_contour_and_segment->second;
ResampledPoint key(ipt, false, 0.);
auto lower = [](const ResampledPoint& l, const ResampledPoint r) { return l.idx_src < r.idx_src || (l.idx_src == r.idx_src && int(l.interpolated) > int(r.interpolated)); };
auto it = std::lower_bound(resampled_point_parameters.begin(), resampled_point_parameters.end(), key, lower);
assert(it != resampled_point_parameters.end() && it->idx_src == ipt && ! it->interpolated);
double t2 = cross2(dir, vptpt2) / denom;
assert(t2 > - EPSILON && t2 < 1. + EPSILON);
if (++ ipt == ipts.size())
param_hi = t2 * dir2.norm();
else
param_hi = it->curve_parameter + t2 * dir2.norm();
}
if (param_lo > param_hi)
std::swap(param_lo, param_hi);
assert(param_lo >= 0. && param_lo <= param_end);
assert(param_hi >= 0. && param_hi <= param_end);
this_valid = param_hi > param_lo + dist_same_contour_reject && param_hi - param_end < param_lo - dist_same_contour_reject;
}
if (t < this->t_min) {
this->t_min = t;
valid = this_valid;
}
}
}
if (! valid)
this->t_min = 1.;
}
// Continue traversing the grid along the edge.
return true;
}
const EdgeGrid::Grid &grid;
const size_t idx_contour;
const std::vector<ResampledPoint> &resampled_point_parameters;
const double dist_same_contour_reject;
size_t idx_point_start;
Point pt_start;
Point pt_end;
Vec2d pt;
Vec2d dir;
// Minium parameter along the vector (pt_end - pt_start).
double t_min;
} visitor(grid, idx_contour, resampled_point_parameters, search_radius);
const Point *pt_this = &contour.back();
size_t idx_pt_this = contour.size() - 1;
const Point *pt_prev = pt_this - 1;
// perpenduclar vector
auto perp = [](const Vec2d& v) -> Vec2d { return Vec2d(v.y(), -v.x()); };
Vec2d vprev = (*pt_this - *pt_prev).cast<double>().normalized();
out.reserve(contour.size() + 1);
for (const Point &pt_next : contour) {
Vec2d vnext = (pt_next - *pt_this).cast<double>().normalized();
Vec2d dir = - (perp(vprev) + perp(vnext)).normalized();
Vec2d dir_perp = perp(dir);
double cross = cross2(vprev, vnext);
double dot = vprev.dot(vnext);
double a = (cross < 0 || dot > 0.5) ? (M_PI / 3.) : (0.48 * acos(std::min(1., - dot)));
// Throw rays, collect distances.
std::vector<double> distances;
int num_rays = 15;
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
SVG svg(debug_out_path("contour_distance_raycasted-%d-%d.svg", iRun, &pt_next - contour.data()).c_str(), bbox);
svg.draw(expoly_grid);
svg.draw_outline(Polygon(contour), "blue", scale_(0.01));
svg.draw(*pt_this, "red", coord_t(scale_(0.1)));
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
for (int i = - num_rays + 1; i < num_rays; ++ i) {
double angle = a * i / (int)num_rays;
double c = cos(angle);
double s = sin(angle);
Vec2d v = c * dir + s * dir_perp;
visitor.init(idx_pt_this, *pt_this, v, search_radius);
grid.visit_cells_intersecting_line(visitor.pt_start, visitor.pt_end, visitor);
distances.emplace_back(visitor.t_min);
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
svg.draw(Line(visitor.pt_start, visitor.pt_end), "yellow", scale_(0.01));
if (visitor.t_min < 1.) {
Vec2d pt = visitor.pt + visitor.dir * visitor.t_min;
svg.draw(Point(pt), "red", coord_t(scale_(0.1)));
}
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
}
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
svg.Close();
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
std::sort(distances.begin(), distances.end());
#if 0
double median = distances[distances.size() / 2];
double standard_deviation = 0;
for (double d : distances)
standard_deviation += (d - median) * (d - median);
standard_deviation = sqrt(standard_deviation / (distances.size() - 1));
double avg = 0;
size_t cnt = 0;
for (double d : distances)
if (d > median - standard_deviation - EPSILON && d < median + standard_deviation + EPSILON) {
avg += d;
++ cnt;
}
avg /= double(cnt);
out.emplace_back(float(avg * search_radius));
#else
out.emplace_back(float(distances.front() * search_radius));
#endif
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
printf("contour_distance_raycasted-%d-%d.svg - distance %lf\n", iRun, int(&pt_next - contour.data()), unscale<double>(out.back()));
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
pt_this = &pt_next;
idx_pt_this = &pt_next - contour.data();
vprev = vnext;
}
// Rotate the vector by one item.
out.emplace_back(out.front());
out.erase(out.begin());
}
return out;
}
// Contour distance by measuring the closest point of an ExPolygon stored inside the EdgeGrid, while filtering out points of the same contour
// at concave regions, or convex regions with low curvature (curvature is estimated as a ratio between contour length and chordal distance crossing the contour ends).
std::vector<float> contour_distance2(const EdgeGrid::Grid &grid, const size_t idx_contour, const Slic3r::Points &contour, const std::vector<ResampledPoint> &resampled_point_parameters, double compensation, double search_radius)
{
assert(! contour.empty());
assert(contour.size() >= 2);
std::vector<float> out;
if (contour.size() > 2)
{
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
static int iRun = 0;
++ iRun;
BoundingBox bbox = get_extents(contour);
bbox.merge(grid.bbox());
ExPolygon expoly_grid;
expoly_grid.contour = Polygon(*grid.contours().front());
for (size_t i = 1; i < grid.contours().size(); ++ i)
expoly_grid.holes.emplace_back(Polygon(*grid.contours()[i]));
#endif
struct Visitor {
Visitor(const EdgeGrid::Grid &grid, const size_t idx_contour, const std::vector<ResampledPoint> &resampled_point_parameters, double dist_same_contour_accept, double dist_same_contour_reject) :
grid(grid), idx_contour(idx_contour), contour(*grid.contours()[idx_contour]), resampled_point_parameters(resampled_point_parameters), dist_same_contour_accept(dist_same_contour_accept), dist_same_contour_reject(dist_same_contour_reject) {}
void init(const Points &contour, const Point &apoint) {
this->idx_point = &apoint - contour.data();
this->point = apoint;
this->found = false;
this->dir_inside = this->dir_inside_at_point(contour, this->idx_point);
}
bool operator()(coord_t iy, coord_t ix) {
// Called with a row and colum of the grid cell, which is intersected by a line.
auto cell_data_range = this->grid.cell_data_range(iy, ix);
for (auto it_contour_and_segment = cell_data_range.first; it_contour_and_segment != cell_data_range.second; ++ it_contour_and_segment) {
// End points of the line segment and their vector.
std::pair<const Point&, const Point&> segment = this->grid.segment(*it_contour_and_segment);
const Vec2d v = (segment.second - segment.first).cast<double>();
const Vec2d va = (this->point - segment.first).cast<double>();
const double l2 = v.squaredNorm(); // avoid a sqrt
const double t = (l2 == 0.0) ? 0. : clamp(0., 1., va.dot(v) / l2);
// Closest point from this->point to the segment.
const Vec2d foot = segment.first.cast<double>() + t * v;
const Vec2d bisector = foot - this->point.cast<double>();
const double dist = bisector.norm();
if ((! this->found || dist < this->distance) && this->dir_inside.dot(bisector) > 0) {
bool accept = true;
if (it_contour_and_segment->first == idx_contour) {
// Complex case: The closest segment originates from the same contour as the starting point.
// Reject the closest point if its distance along the contour is reasonable compared to the current contour bisector (this->pt, foot).
double param_lo = resampled_point_parameters[this->idx_point].curve_parameter;
double param_hi;
double param_end = resampled_point_parameters.back().curve_parameter;
const Slic3r::Points &ipts = *grid.contours()[it_contour_and_segment->first];
const size_t ipt = it_contour_and_segment->second;
{
ResampledPoint key(ipt, false, 0.);
auto lower = [](const ResampledPoint& l, const ResampledPoint r) { return l.idx_src < r.idx_src || (l.idx_src == r.idx_src && int(l.interpolated) > int(r.interpolated)); };
auto it = std::lower_bound(resampled_point_parameters.begin(), resampled_point_parameters.end(), key, lower);
assert(it != resampled_point_parameters.end() && it->idx_src == ipt && ! it->interpolated);
param_hi = t * sqrt(l2);
if (ipt + 1 < ipts.size())
param_hi += it->curve_parameter;
}
if (param_lo > param_hi)
std::swap(param_lo, param_hi);
assert(param_lo > - SCALED_EPSILON && param_lo <= param_end + SCALED_EPSILON);
assert(param_hi > - SCALED_EPSILON && param_hi <= param_end + SCALED_EPSILON);
double dist_along_contour = std::min(param_hi - param_lo, param_lo + param_end - param_hi);
if (dist_along_contour < dist_same_contour_accept)
accept = false;
else if (dist < dist_same_contour_reject + SCALED_EPSILON) {
// this->point is close to foot. This point will only be accepted if the path along the contour is significantly
// longer than the bisector. That is, the path shall not bulge away from the bisector too much.
// Bulge is estimated by 0.6 of the circle circumference drawn around the bisector.
// Test whether the contour is convex or concave.
bool inside =
(t == 0.) ? this->inside_corner(ipts, ipt, this->point) :
(t == 1.) ? this->inside_corner(ipts, ipt + 1 == ipts.size() ? 0 : ipt + 1, this->point) :
this->left_of_segment(ipts, ipt, this->point);
accept = inside && dist_along_contour > 0.6 * M_PI * dist;
}
}
if (accept && (! this->found || dist < this->distance)) {
// Simple case: Just measure the shortest distance.
this->distance = dist;
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
this->closest_point = foot.cast<coord_t>();
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
this->found = true;
}
}
}
// Continue traversing the grid.
return true;
}
const EdgeGrid::Grid &grid;
const size_t idx_contour;
const Points &contour;
const std::vector<ResampledPoint> &resampled_point_parameters;
const double dist_same_contour_accept;
const double dist_same_contour_reject;
size_t idx_point;
Point point;
// Direction inside the contour from idx_point, not normalized.
Vec2d dir_inside;
bool found;
double distance;
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
Point closest_point;
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
private:
static Vec2d dir_inside_at_point(const Points &contour, size_t i) {
size_t iprev = prev_idx_modulo(i, contour);
size_t inext = next_idx_modulo(i, contour);
Vec2d v1 = (contour[i] - contour[iprev]).cast<double>();
Vec2d v2 = (contour[inext] - contour[i]).cast<double>();
return Vec2d(- v1.y() - v2.y(), v1.x() + v2.x());
}
static Vec2d dir_inside_at_segment(const Points& contour, size_t i) {
size_t inext = next_idx_modulo(i, contour);
Vec2d v = (contour[inext] - contour[i]).cast<double>();
return Vec2d(- v.y(), v.x());
}
static bool inside_corner(const Slic3r::Points &contour, size_t i, const Point &pt_oposite) {
const Vec2d pt = pt_oposite.cast<double>();
size_t iprev = prev_idx_modulo(i, contour);
size_t inext = next_idx_modulo(i, contour);
Vec2d v1 = (contour[i] - contour[iprev]).cast<double>();
Vec2d v2 = (contour[inext] - contour[i]).cast<double>();
bool left_of_v1 = cross2(v1, pt - contour[iprev].cast<double>()) > 0.;
bool left_of_v2 = cross2(v2, pt - contour[i ].cast<double>()) > 0.;
return cross2(v1, v2) > 0 ?
left_of_v1 && left_of_v2 : // convex corner
left_of_v1 || left_of_v2; // concave corner
}
static bool left_of_segment(const Slic3r::Points &contour, size_t i, const Point &pt_oposite) {
const Vec2d pt = pt_oposite.cast<double>();
size_t inext = next_idx_modulo(i, contour);
Vec2d v = (contour[inext] - contour[i]).cast<double>();
return cross2(v, pt - contour[i].cast<double>()) > 0.;
}
} visitor(grid, idx_contour, resampled_point_parameters, 0.5 * compensation * M_PI, search_radius);
out.reserve(contour.size());
Point radius_vector(search_radius, search_radius);
for (const Point &pt : contour) {
visitor.init(contour, pt);
grid.visit_cells_intersecting_box(BoundingBox(pt - radius_vector, pt + radius_vector), visitor);
out.emplace_back(float(visitor.found ? std::min(visitor.distance, search_radius) : search_radius));
#if 0
//#ifdef CONTOUR_DISTANCE_DEBUG_SVG
if (out.back() < search_radius) {
SVG svg(debug_out_path("contour_distance_filtered-%d-%d.svg", iRun, int(&pt - contour.data())).c_str(), bbox);
svg.draw(expoly_grid);
svg.draw_outline(Polygon(contour), "blue", scale_(0.01));
svg.draw(pt, "green", coord_t(scale_(0.1)));
svg.draw(visitor.closest_point, "red", coord_t(scale_(0.1)));
printf("contour_distance_filtered-%d-%d.svg - distance %lf\n", iRun, int(&pt - contour.data()), unscale<double>(out.back()));
}
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
}
#ifdef CONTOUR_DISTANCE_DEBUG_SVG
if (out.back() < search_radius) {
SVG svg(debug_out_path("contour_distance_filtered-final-%d.svg", iRun).c_str(), bbox);
svg.draw(expoly_grid);
svg.draw_outline(Polygon(contour), "blue", scale_(0.01));
for (size_t i = 0; i < contour.size(); ++ i)
svg.draw(contour[i], out[i] < float(search_radius - SCALED_EPSILON) ? "red" : "green", coord_t(scale_(0.1)));
}
#endif /* CONTOUR_DISTANCE_DEBUG_SVG */
}
return out;
}
Points resample_polygon(const Points &contour, double dist, std::vector<ResampledPoint> &resampled_point_parameters)
{
Points out;
out.reserve(contour.size());
resampled_point_parameters.reserve(contour.size());
if (contour.size() > 2) {
Vec2d pt_prev = contour.back().cast<double>();
for (const Point &pt : contour) {
size_t idx_this = &pt - contour.data();
const Vec2d pt_this = pt.cast<double>();
const Vec2d v = pt_this - pt_prev;
const double l = v.norm();
const size_t n = size_t(ceil(l / dist));
const double l_step = l / n;
for (size_t i = 1; i < n; ++ i) {
double interpolation_parameter = double(i) / n;
Vec2d new_pt = pt_prev + v * interpolation_parameter;
out.emplace_back(new_pt.cast<coord_t>());
resampled_point_parameters.emplace_back(idx_this, true, l_step);
}
out.emplace_back(pt);
resampled_point_parameters.emplace_back(idx_this, false, l_step);
pt_prev = pt_this;
}
for (size_t i = 1; i < resampled_point_parameters.size(); ++i)
resampled_point_parameters[i].curve_parameter += resampled_point_parameters[i - 1].curve_parameter;
}
return out;
}
static inline void smooth_compensation(std::vector<float> &compensation, float strength, size_t num_iterations)
{
std::vector<float> out(compensation);
for (size_t iter = 0; iter < num_iterations; ++ iter) {
for (size_t i = 0; i < compensation.size(); ++ i) {
float prev = prev_value_modulo(i, compensation);
float next = next_value_modulo(i, compensation);
float laplacian = compensation[i] * (1.f - strength) + 0.5f * strength * (prev + next);
// Compensations are negative. Only apply the laplacian if it leads to lower compensation.
out[i] = std::max(laplacian, compensation[i]);
}
out.swap(compensation);
}
}
static inline void smooth_compensation_banded(const Points &contour, float band, std::vector<float> &compensation, float strength, size_t num_iterations)
{
assert(contour.size() == compensation.size());
assert(contour.size() > 2);
std::vector<float> out(compensation);
float dist_min2 = band * band;
static constexpr bool use_min = false;
for (size_t iter = 0; iter < num_iterations; ++ iter) {
for (int i = 0; i < int(compensation.size()); ++ i) {
const Vec2f pthis = contour[i].cast<float>();
int j = prev_idx_modulo(i, contour);
Vec2f pprev = contour[j].cast<float>();
float prev = compensation[j];
float l2 = (pthis - pprev).squaredNorm();
if (l2 < dist_min2) {
float l = sqrt(l2);
int jprev = exchange(j, prev_idx_modulo(j, contour));
while (j != i) {
const Vec2f pp = contour[j].cast<float>();
const float lthis = (pp - pprev).norm();
const float lnext = l + lthis;
if (lnext > band) {
// Interpolate the compensation value.
prev = use_min ?
std::min(prev, lerp(compensation[jprev], compensation[j], (band - l) / lthis)) :
lerp(compensation[jprev], compensation[j], (band - l) / lthis);
break;
}
prev = use_min ? std::min(prev, compensation[j]) : compensation[j];
pprev = pp;
l = lnext;
jprev = exchange(j, prev_idx_modulo(j, contour));
}
}
j = next_idx_modulo(i, contour);
pprev = contour[j].cast<float>();
float next = compensation[j];
l2 = (pprev - pthis).squaredNorm();
if (l2 < dist_min2) {
float l = sqrt(l2);
int jprev = exchange(j, next_idx_modulo(j, contour));
while (j != i) {
const Vec2f pp = contour[j].cast<float>();
const float lthis = (pp - pprev).norm();
const float lnext = l + lthis;
if (lnext > band) {
// Interpolate the compensation value.
next = use_min ?
std::min(next, lerp(compensation[jprev], compensation[j], (band - l) / lthis)) :
lerp(compensation[jprev], compensation[j], (band - l) / lthis);
break;
}
next = use_min ? std::min(next, compensation[j]) : compensation[j];
pprev = pp;
l = lnext;
jprev = exchange(j, next_idx_modulo(j, contour));
}
}
float laplacian = compensation[i] * (1.f - strength) + 0.5f * strength * (prev + next);
// Compensations are negative. Only apply the laplacian if it leads to lower compensation.
out[i] = std::max(laplacian, compensation[i]);
}
out.swap(compensation);
}
}
ExPolygon elephant_foot_compensation(const ExPolygon &input_expoly, const Flow &external_perimeter_flow, const double compensation)
{
// The contour shall be wide enough to apply the external perimeter plus compensation on both sides.
double min_contour_width = double(external_perimeter_flow.scaled_width() + external_perimeter_flow.scaled_spacing());
double scaled_compensation = scale_(compensation);
double min_contour_width_compensated = min_contour_width + 2. * scaled_compensation;
// Make the search radius a bit larger for the averaging in contour_distance over a fan of rays to work.
double search_radius = min_contour_width_compensated + min_contour_width * 0.5;
BoundingBox bbox = get_extents(input_expoly.contour);
Point bbox_size = bbox.size();
ExPolygon out;
if (bbox_size.x() < min_contour_width_compensated + SCALED_EPSILON ||
bbox_size.y() < min_contour_width_compensated + SCALED_EPSILON ||
input_expoly.area() < min_contour_width_compensated * min_contour_width_compensated * 5.)
{
// The contour is tiny. Don't correct it.
out = input_expoly;
}
else
{
EdgeGrid::Grid grid;
ExPolygon simplified = input_expoly.simplify(SCALED_EPSILON).front();
BoundingBox bbox = get_extents(simplified.contour);
bbox.offset(SCALED_EPSILON);
grid.set_bbox(bbox);
grid.create(simplified, coord_t(0.7 * search_radius));
std::vector<std::vector<float>> deltas;
deltas.reserve(simplified.holes.size() + 1);
ExPolygon resampled(simplified);
double resample_interval = scale_(0.5);
for (size_t idx_contour = 0; idx_contour <= simplified.holes.size(); ++ idx_contour) {
Polygon &poly = (idx_contour == 0) ? resampled.contour : resampled.holes[idx_contour - 1];
std::vector<ResampledPoint> resampled_point_parameters;
poly.points = resample_polygon(poly.points, resample_interval, resampled_point_parameters);
std::vector<float> dists = contour_distance2(grid, idx_contour, poly.points, resampled_point_parameters, scaled_compensation, search_radius);
for (float &d : dists) {
// printf("Point %d, Distance: %lf\n", int(&d - dists.data()), unscale<double>(d));
// Convert contour width to available compensation distance.
if (d < min_contour_width)
d = 0.f;
else if (d > min_contour_width_compensated)
d = - float(scaled_compensation);
else
d = - (d - float(min_contour_width)) / 2.f;
assert(d >= - float(scaled_compensation) && d <= 0.f);
}
// smooth_compensation(dists, 0.4f, 10);
smooth_compensation_banded(poly.points, float(0.8 * resample_interval), dists, 0.3f, 3);
deltas.emplace_back(dists);
}
ExPolygons out_vec = variable_offset_inner_ex(resampled, deltas, 2.);
if (out_vec.size() == 1)
out = std::move(out_vec.front());
else {
// Something went wrong, don't compensate.
out = input_expoly;
#ifdef TESTS_EXPORT_SVGS
if (out_vec.size() > 1) {
static int iRun = 0;
SVG::export_expolygons(debug_out_path("elephant_foot_compensation-many_contours-%d.svg", iRun ++).c_str(),
{ { { input_expoly }, { "gray", "black", "blue", coord_t(scale_(0.02)), 0.5f, "black", coord_t(scale_(0.05)) } },
{ { out_vec }, { "gray", "black", "blue", coord_t(scale_(0.02)), 0.5f, "black", coord_t(scale_(0.05)) } } });
}
#endif /* TESTS_EXPORT_SVGS */
assert(out_vec.size() == 1);
}
}
return out;
}
ExPolygons elephant_foot_compensation(const ExPolygons &input, const Flow &external_perimeter_flow, const double compensation)
{
ExPolygons out;
out.reserve(input.size());
for (const ExPolygon &expoly : input)
out.emplace_back(elephant_foot_compensation(expoly, external_perimeter_flow, compensation));
return out;
}
} // namespace Slic3r
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