3D-printing/OrcaSlicer
1
0
Fork 0
mirror of https://github.com/SoftFever/OrcaSlicer.git synced 2025-07-22 06:04:01 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions 3

Follow-up to 5276bd98d7:

Browse source 
WIP: MutablePolygon - linked list based polygon implementation
allowing rapid insertion and removal of points.
WIP: porting smooth_outward() from Cura.
This commit is contained in:
Vojtech Bubnik 2021-03-03 15:04:15 +01:00
parent 6a46b71dc1
commit 5f5de1c812
3 changed files with 428 additions and 197 deletions
Download patch file Download diff file Expand all files Collapse all files

445
src/libslic3r/MutablePolygon.cpp
View file

@ -1,5 +1,6 @@
#include "MutablePolygon.hpp"
#include "Line.hpp"
#include "libslic3r.h"
namespace Slic3r {
@ -36,207 +37,295 @@ void remove_duplicates(MutablePolygon &polygon, double eps)
}
}
// Sample a point on line (a, b) at distance "dist" from ref_pt.
// If two points fulfill the condition, then the first one (closer to point a) is taken.
// If none of the two points falls on line (a, b), return false.
template<typename VectorType>
static inline VectorType point_on_line_at_dist(const VectorType &a, const VectorType &b, const VectorType &ref_pt, const double dist)
// Adapted from Cura ConstPolygonRef::smooth_corner_complex() by Tim Kuipers.
// A concave corner at it1 with position p1 has been removed by the caller between it0 and it2, where |p2 - p0| < shortcut_length.
// Now try to close a concave crack by walking left from it0 and right from it2 as long as the new clipping edge is smaller than shortcut_length
// and the new clipping edge is still inside the polygon (it is a diagonal, it does not intersect polygon boundary).
// Once the traversal stops (always at a clipping edge shorter than shortcut_length), the final trapezoid is clipped with a new clipping edge of shortcut_length.
// Return true if a hole was completely closed (degenerated to an empty polygon) or a single CCW triangle was left, which is not to be simplified any further.
// it0, it2 are updated to the final clipping edge.
static bool clip_narrow_corner(
const Vec2i64 p1,
MutablePolygon::iterator &it0,
MutablePolygon::iterator &it2,
MutablePolygon::range &unprocessed_range,
int64_t dist2_current,
const int64_t shortcut_length)
{
using T = typename VectorType::Scalar;
auto v = b - a;
auto l2 = v.squaredNorm();
assert(l2 > T(0));
auto vpt = ref_pt - a;
// Parameter of the foot point of ref_pt on line (a, b).
auto t = v.dot(vpt) / l2;
// Foot point of ref_pt on line (a, b).
auto foot_pt = a + t * v;
auto dfoot2 = vpt.squaredNorm() - (foot_pt - ref_pt).squaredNorm();
// Distance of the result point from the foot point, normalized to length of (a, b).
auto dfoot = dfoot2 > T(0) ? sqrt(dfoot2) / sqrt(l2) : T(0);
auto t_result = t - dfoot;
if (t_result < T(0))
t_result = t + dfoot;
t_result = Slic3r::clamp(0., 1., t_result);
return a + v * t;
}
MutablePolygon &polygon = it0.polygon();
assert(polygon.size() >= 2);
static bool smooth_corner_complex(const Vec2d p1, MutablePolygon::iterator &it0, MutablePolygon::iterator &it2, const double shortcut_length)
{
// walk away from the corner until the shortcut > shortcut_length or it would smooth a piece inward
// - walk in both directions untill shortcut > shortcut_length
// - stop walking in one direction if it would otherwise cut off a corner in that direction
// - same in the other direction
// - stop if both are cut off
// walk by updating p0_it and p2_it
double shortcut_length2 = shortcut_length * shortcut_length;
bool forward_is_blocked = false;
bool forward_is_too_far = false;
bool backward_is_blocked = false;
bool backward_is_too_far = false;
for (;;) {
const bool forward_has_converged = forward_is_blocked || forward_is_too_far;
const bool backward_has_converged = backward_is_blocked || backward_is_too_far;
if (forward_has_converged && backward_has_converged) {
if (forward_is_too_far && backward_is_too_far && (*it0.prev() - *it2.next()).cast<double>().squaredNorm() < shortcut_length2) {
// Trim the narrowing region.
-- it0;
++ it2;
forward_is_too_far = false;
backward_is_too_far = false;
continue;
} else
break;
}
const int64_t shortcut_length2 = sqr(shortcut_length);
const Vec2d p0 = it0->cast<double>();
const Vec2d p2 = it2->cast<double>();
if (! forward_has_converged && (backward_has_converged || (p2 - p1).squaredNorm() < (p0 - p1).squaredNorm())) {
// walk forward
const auto it2_2 = it2.next();
const Vec2d p2_2 = it2_2->cast<double>();
if (cross2(p2 - p0, p2_2 - p0) > 0) {
forward_is_blocked = true;
} else if ((p2_2 - p0).squaredNorm() > shortcut_length2) {
forward_is_too_far = true;
enum Status {
Free,
Blocked,
Far,
};
Status forward = Free;
Status backward = Free;
Vec2i64 p0 = it0->cast<int64_t>();
Vec2i64 p2 = it2->cast<int64_t>();
Vec2i64 p02;
Vec2i64 p22;
int64_t dist2_next;
// As long as there is at least a single triangle left in the polygon.
while (polygon.size() >= 3) {
assert(dist2_current <= shortcut_length2);
if (forward == Far && backward == Far) {
p02 = it0.prev()->cast<int64_t>();
p22 = it2.next()->cast<int64_t>();
auto d2 = (p22 - p02).squaredNorm();
if (d2 <= shortcut_length2) {
// The region was narrow until now and it is still narrow. Trim at both sides.
it0 = unprocessed_range.remove_back(it0).prev();
it2 = unprocessed_range.remove_front(it2);
if (polygon.size() <= 2)
// A hole degenerated to an empty polygon.
return true;
forward = Free;
backward = Free;
dist2_current = d2;
p0 = p02;
p2 = p22;
} else {
it2 = it2_2; // make one step in the forward direction
backward_is_blocked = false; // invalidate data about backward walking
backward_is_too_far = false;
// The region is widening. Stop traversal and trim the final trapezoid.
dist2_next = d2;
break;
}
} else if (forward != Free && backward != Free)
// One of the corners is blocked, the other is blocked or too far. Stop traversal.
break;
// Try to proceed by flipping a diagonal.
// Progress by keeping the distance of the clipping edge end points equal to initial p1.
//FIXME This is an arbitrary condition, maybe a more local condition will be better (take a shorter diagonal?).
if (forward == Free && (backward != Free || (p2 - p1).squaredNorm() < (p0 - p1).cast<int64_t>().squaredNorm())) {
p22 = it2.next()->cast<int64_t>();
if (cross2(p2 - p0, p22 - p0) > 0)
forward = Blocked;
else {
// New clipping edge lenght.
auto d2 = (p22 - p0).squaredNorm();
if (d2 > shortcut_length2) {
forward = Far;
dist2_next = d2;
} else {
forward = Free;
// Make one step in the forward direction.
it2 = unprocessed_range.remove_front(it2);
p2 = p22;
dist2_current = d2;
}
}
} else {
// walk backward
const auto it0_2 = it0.prev();
const Vec2d p0_2 = it0_2->cast<double>();
if (cross2(p0_2 - p0, p2 - p0_2) > 0) {
backward_is_blocked = true;
} else if ((p2 - p0_2).squaredNorm() > shortcut_length2) {
backward_is_too_far = true;
} else {
it0 = it0_2; // make one step in the backward direction
forward_is_blocked = false; // invalidate data about forward walking
forward_is_too_far = false;
}
}
if (it0.prev() == it2 || it0 == it2) {
// stop if we went all the way around the polygon
// this should only be the case for hole polygons (?)
if (forward_is_too_far && backward_is_too_far) {
// in case p0_it.prev() == p2_it :
// / .
// / /|
// | becomes | |
// \ \|
// \ .
// in case p0_it == p2_it :
// / .
// / becomes /|
// \ \|
// \ .
break;
} else {
// this whole polygon can be removed
return true;
assert(backward == Free);
p02 = it0.prev()->cast<int64_t>();
if (cross2(p0 - p2, p02 - p2) > 0)
backward = Blocked;
else {
// New clipping edge lenght.
auto d2 = (p2 - p02).squaredNorm();
if (d2 > shortcut_length2) {
backward = Far;
dist2_next = d2;
} else {
backward = Free;
// Make one step in the backward direction.
it0 = unprocessed_range.remove_back(it0).prev();
p0 = p02;
dist2_current = d2;
}
}
}
}
const Vec2d p0 = it0->cast<double>();
const Vec2d p2 = it2->cast<double>();
const Vec2d v02 = p2 - p0;
const int64_t l2_v02 = v02.squaredNorm();
if (std::abs(l2_v02 - shortcut_length2) < shortcut_length * 10) // i.e. if (size2 < l * (l+10) && size2 > l * (l-10))
{ // v02 is approximately shortcut length
// handle this separately to avoid rounding problems below in the getPointOnLineWithDist function
// p0_it and p2_it are already correct
} else if (! backward_is_blocked && ! forward_is_blocked) {
const auto l_v02 = sqrt(l2_v02);
const Vec2d p0_2 = it0.prev()->cast<double>();
const Vec2d p2_2 = it2.next()->cast<double>();
double t = Slic3r::clamp(0., 1., (shortcut_length - l_v02) / ((p2_2 - p0_2).norm() - l_v02));
it0 = it0.prev().insert((p0 + (p0_2 - p0) * t).cast<coord_t>());
it2 = it2.insert((p2 + (p2_2 - p2) * t).cast<coord_t>());
} else if (! backward_is_blocked) {
it0 = it0.prev().insert(point_on_line_at_dist(p0, Vec2d(it0.prev()->cast<double>()), p2, shortcut_length).cast<coord_t>());
} else if (! forward_is_blocked) {
it2 = it2.insert(point_on_line_at_dist(p2, Vec2d(it2.next()->cast<double>()), p0, shortcut_length).cast<coord_t>());
if (polygon.size() <= 3) {
// A hole degenerated to an empty polygon, or a tiny triangle remained.
assert(polygon.size() < 3 || (forward == Blocked && backward == Blocked) || (forward == Far && backward == Far));
if (polygon.size() < 3 || forward == Far) {
assert(polygon.size() < 3 || dist2_current <= shortcut_length2);
polygon.clear();
} else {
// The remaining triangle is CCW oriented, keep it.
}
return true;
}
assert(dist2_current <= shortcut_length2);
if ((forward == Blocked && backward == Blocked) || dist2_current > sqr(shortcut_length - int64_t(SCALED_EPSILON))) {
// The crack is filled, keep the last clipping edge.
} else if (dist2_next < sqr(shortcut_length - int64_t(SCALED_EPSILON))) {
// To avoid creating tiny edges.
if (forward == Far)
it0 = unprocessed_range.remove_back(it0).prev();
if (backward == Far)
it2 = unprocessed_range.remove_front(it2);
if (polygon.size() <= 2)
// A hole degenerated to an empty polygon.
return true;
} else if (forward == Blocked || backward == Blocked) {
// One side is far, the other blocked.
assert(forward == Far || backward == Far);
if (backward == Far) {
// Sort, so we will clip the 1st edge.
std::swap(p0, p2);
std::swap(p02, p22);
}
// Find point on (p0, p02) at distance shortcut_length from p2.
// Circle intersects a line at two points, however because |p2 - p0| < shortcut_length,
// only the second intersection is valid. Because |p2 - p02| > shortcut_length, such
// intersection should always be found on (p0, p02).
const Vec2d v = (p02 - p0).cast<double>();
const Vec2d d = (p0 - p2).cast<double>();
const double a = v.squaredNorm();
const double b = 2. * double(d.dot(v));
double u = b * b - 4. * a * (d.squaredNorm() - shortcut_length2);
assert(u > 0.);
u = sqrt(u);
double t = (- b + u) / (2. * a);
assert(t > 0. && t < 1.);
(backward == Far ? *it2 : *it0) += (v.cast<double>() * t).cast<coord_t>();
} else {
// |
// __|2
// | / > shortcut cannot be of the desired length
// ___|/ .
// 0
// both are blocked and p0_it and p2_it are already correct
// The trapezoid (it0.prev(), it0, it2, it2.next()) is widening. Trim it.
assert(forward == Far && backward == Far);
assert(dist2_next > shortcut_length2);
const double dcurrent = sqrt(double(dist2_current));
double t = (shortcut_length - dcurrent) / (sqrt(double(dist2_next)) - dcurrent);
assert(t > 0. && t < 1.);
*it0 += ((p02 - p0).cast<double>() * t).cast<coord_t>();
*it2 += ((p22 - p2).cast<double>() * t).cast<coord_t>();
}
// Delete all the points between it0 and it2.
while (it0.next() != it2)
it0.next().remove();
return false;
}
void smooth_outward(MutablePolygon &polygon, double shortcut_length)
// adapted from Cura ConstPolygonRef::smooth_outward() by Tim Kuipers.
void smooth_outward(MutablePolygon &polygon, coord_t clip_dist_scaled)
{
remove_duplicates(polygon, scaled<double>(0.01));
const int shortcut_length2 = shortcut_length * shortcut_length;
static constexpr const double cos_min_angle = -0.70710678118654752440084436210485; // cos(135 degrees)
const auto clip_dist_scaled2 = sqr<int64_t>(clip_dist_scaled);
const auto clip_dist_scaled2eps = sqr(clip_dist_scaled + int64_t(SCALED_EPSILON));
const auto foot_dist_min2 = sqr(SCALED_EPSILON);
MutablePolygon::iterator it1 = polygon.begin();
do {
const Vec2d p1 = it1->cast<double>();
auto it0 = it1.prev();
auto it2 = it1.next();
const Vec2d p0 = it0->cast<double>();
const Vec2d p2 = it2->cast<double>();
const Vec2d v1 = p0 - p1;
const Vec2d v2 = p2 - p1;
const double cos_angle = v1.dot(v2);
if (cos_angle < cos_min_angle && cross2(v1, v2) < 0) {
// Simplify the sharp angle.
const Vec2d v02 = p2 - p0;
const double l2_v02 = v02.squaredNorm();
if (l2_v02 >= shortcut_length2) {
// Trim an obtuse corner.
// Each source point will be visited exactly once.
MutablePolygon::range unprocessed_range(polygon);
while (! unprocessed_range.empty() && polygon.size() > 2) {
auto it1 = unprocessed_range.process_next();
auto it0 = it1.prev();
auto it2 = it1.next();
const Point p0 = *it0;
const Point p1 = *it1;
const Point p2 = *it2;
const Vec2i64 v1 = (p0 - p1).cast<int64_t>();
const Vec2i64 v2 = (p2 - p1).cast<int64_t>();
if (cross2(v1, v2) > 0) {
// Concave corner.
int64_t dot = v1.dot(v2);
auto l2v1 = double(v1.squaredNorm());
auto l2v2 = double(v2.squaredNorm());
if (dot > 0 || Slic3r::sqr(double(dot)) * 2. < l2v1 * l2v2) {
// Angle between v1 and v2 bigger than 135 degrees.
// Simplify the sharp angle.
Vec2i64 v02 = (p2 - p0).cast<int64_t>();
int64_t l2v02 = v02.squaredNorm();
it1.remove();
if (l2_v02 > Slic3r::sqr(shortcut_length + SCALED_EPSILON)) {
double l2_1 = v1.squaredNorm();
double l2_2 = v2.squaredNorm();
bool trim = true;
if (cos_angle > 0.9999) {
// The triangle p0, p1, p2 is likely degenerate.
// Measure height of the triangle.
double d2 = l2_1 > l2_2 ? line_alg::distance_to_squared(Linef{ p0, p1 }, p2) : line_alg::distance_to_squared(Linef{ p2, p1 }, p0);
if (d2 < Slic3r::sqr(scaled<double>(0.02)))
trim = false;
}
if (trim) {
Vec2d bisector = v1 / l2_1 + v2 / l2_2;
double d1 = v1.dot(bisector) / l2_1;
double d2 = v2.dot(bisector) / l2_2;
double lbisector = bisector.norm();
if (d1 < shortcut_length && d2 < shortcut_length) {
it0.insert((p1 + v1 * (shortcut_length / d1)).cast<coord_t>())
.insert((p1 + v2 * (shortcut_length / d2)).cast<coord_t>());
} else if (v1.squaredNorm() < v2.squaredNorm())
it0.insert(point_on_line_at_dist(p1, p2, p0, shortcut_length).cast<coord_t>());
else
it0.insert(point_on_line_at_dist(p1, p0, p2, shortcut_length).cast<coord_t>());
if (l2v02 < clip_dist_scaled2) {
// (p0, p2) is short.
// Clip a sharp concave corner by possibly expanding the trimming region left of it0 and right of it2.
// Updates it0, it2 and num_to_process.
if (clip_narrow_corner(p1.cast<int64_t>(), it0, it2, unprocessed_range, l2v02, clip_dist_scaled))
// Trimmed down to an empty polygon or to a single CCW triangle.
return;
} else {
// Clip an obtuse corner.
if (l2v02 > clip_dist_scaled2eps) {
Vec2d v1d = v1.cast<double>();
Vec2d v2d = v2.cast<double>();
// Sort v1d, v2d, shorter first.
bool swap = l2v1 > l2v2;
if (swap) {
std::swap(v1d, v2d);
std::swap(l2v1, l2v2);
}
double lv1 = sqrt(l2v1);
double lv2 = sqrt(l2v2);
// Bisector between v1 and v2.
Vec2d bisector = v1d / lv1 + v2d / lv2;
double l2bisector = bisector.squaredNorm();
// Squared distance of the end point of v1 to the bisector.
double d2 = l2v1 - sqr(v1d.dot(bisector)) / l2bisector;
if (d2 < foot_dist_min2) {
// Height of the p1, p0, p2 triangle is tiny. Just remove p1.
} else if (d2 < 0.25 * clip_dist_scaled2 + SCALED_EPSILON) {
// The shorter vector is too close to the bisector. Trim the shorter vector fully,
// trim the longer vector partially.
// Intersection of a circle at p2 of radius = clip_dist_scaled
// with a ray (p1, p0), take the intersection after the foot point.
// The intersection shall always exist because |p2 - p1| > clip_dist_scaled.
const double b = - 2. * v1d.cast<double>().dot(v2d);
double u = b * b - 4. * l2v2 * (double(l2v1) - clip_dist_scaled2);
assert(u > 0.);
// Take the second intersection along v2.
double t = (- b + sqrt(u)) / (2. * l2v2);
assert(t > 0. && t < 1.);
Point pt_new = p1 + (t * v2d).cast<coord_t>();
#ifndef NDEBUG
double d2new = (pt_new - (swap ? p2 : p0)).cast<double>().squaredNorm();
assert(std::abs(d2new - clip_dist_scaled2) < sqr(10. * SCALED_EPSILON));
#endif // NDEBUG
it2.insert(pt_new);
} else {
// Cut the corner with a line perpendicular to the bisector.
double t = sqrt(0.25 * clip_dist_scaled2 / d2);
assert(t > 0. && t < 1.);
Point p0 = p1 + (v1d * t).cast<coord_t>();
Point p2 = p1 + (v2d * (t * lv2 / lv1)).cast<coord_t>();
if (swap)
std::swap(p0, p2);
it2.insert(p2).insert(p0);
}
} else {
// Just remove p1.
assert(l2v02 >= clip_dist_scaled2 && l2v02 <= clip_dist_scaled2eps);
}
}
} else {
bool remove_poly = smooth_corner_complex(p1, it0, it2, shortcut_length); // edits p0_it and p2_it!
if (remove_poly) {
// don't convert ListPolygon into result
return;
}
}
// update:
it1 = it2; // next point to consider for whether it's an internal corner
}
else
it1 = it2;
} else
++ it1;
} else
++ it1;
} while (it1 != polygon.begin());
}
if (polygon.size() == 3) {
// Check whether the last triangle is clockwise oriented (it is a hole) and its height is below clip_dist_scaled.
// If so, fill in the hole.
const Point p0 = *polygon.begin().prev();
const Point p1 = *polygon.begin();
const Point p2 = *polygon.begin().next();
Vec2i64 v1 = (p0 - p1).cast<int64_t>();
Vec2i64 v2 = (p2 - p1).cast<int64_t>();
if (cross2(v1, v2) > 0) {
// CW triangle. Measure its height.
const Vec2i64 v3 = (p2 - p0).cast<int64_t>();
int64_t l12 = v1.squaredNorm();
int64_t l22 = v2.squaredNorm();
int64_t l32 = v3.squaredNorm();
if (l22 > l12 && l22 > l32) {
std::swap(v1, v2);
std::swap(l12, l22);
} else if (l32 > l12 && l32 > l22) {
v1 = v3;
l12 = l32;
}
auto h2 = l22 - sqr(double(v1.dot(v2))) / double(l12);
if (h2 < clip_dist_scaled2)
// CW triangle with a low height. Close the hole.
polygon.clear();
}
} else if (polygon.size() < 3)
polygon.clear();
}
} // namespace Slic3r