3D-printing/OrcaSlicer
1
0
Fork 0
mirror of https://github.com/SoftFever/OrcaSlicer.git synced 2025-07-21 21:58:03 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions 3

WIP: MutablePolygon - linked list based polygon implementation

Browse source 
allowing rapid insertion and removal of points.
WIP: porting smooth_outward() from Cura.
This commit is contained in:
Vojtech Bubnik 2021-03-01 18:41:36 +01:00
parent 409849d238
commit 5276bd98d7
6 changed files with 632 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

242
src/libslic3r/MutablePolygon.cpp Normal file
View file

@ -0,0 +1,242 @@
#include "MutablePolygon.hpp"
#include "Line.hpp"
namespace Slic3r {
// Remove exact duplicate points. May reduce the polygon down to empty polygon.
void remove_duplicates(MutablePolygon &polygon)
{
if (! polygon.empty()) {
auto begin = polygon.begin();
auto it = begin;
for (++ it; it != begin;) {
auto prev = it.prev();
if (*prev == *it)
it = it.remove();
else
++ it;
}
}
}
// Remove nearly duplicate points. May reduce the polygon down to empty polygon.
void remove_duplicates(MutablePolygon &polygon, double eps)
{
if (! polygon.empty()) {
auto eps2 = eps * eps;
auto begin = polygon.begin();
auto it = begin;
for (++ it; it != begin;) {
auto prev = it.prev();
if ((*it - *prev).cast<double>().squaredNorm() < eps2)
it = it.remove();
else
++ it;
}
}
}
// 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)
{
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;
}
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 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;
} 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;
}
} 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;
}
}
}
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>());
} else {
// |
// __|2
// | / > shortcut cannot be of the desired length
// ___|/ .
// 0
// both are blocked and p0_it and p2_it are already correct
}
// 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)
{
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)
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.
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>());
}
}
} 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;
} while (it1 != polygon.begin());
}
} // namespace Slic3r