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ArcWelder: Fixing some edge conditions with least squares fitting.

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This commit is contained in:
Vojtech Bubnik 2023-10-03 14:35:31 +02:00
parent a693adbeab
commit 5b45777d4b
1 changed files with 48 additions and 42 deletions
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90
src/libslic3r/Geometry/ArcWelder.cpp
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@ -264,44 +264,47 @@ static std::optional<Circle> try_create_circle(const Points::const_iterator begi
// of all points on the polyline to be fitted.
Vec2i64 first_point = begin->cast<int64_t>();
Vec2i64 last_point = std::prev(end)->cast<int64_t>();
Vec2i64 c = (first_point.cast<int64_t>() + last_point.cast<int64_t>()) / 2;
Vec2i64 v = last_point - first_point;
Vec2i64 prev_point = first_point;
int prev_side = sign(v.dot(prev_point - c));
assert(prev_side != 0);
Point point_on_bisector;
#ifndef NDEBUG
point_on_bisector = { std::numeric_limits<coord_t>::max(), std::numeric_limits<coord_t>::max() };
#endif // NDEBUG
for (auto it = std::next(begin); it != end; ++ it) {
Vec2i64 this_point = it->cast<int64_t>();
int64_t d = v.dot(this_point - c);
int this_side = sign(d);
int sideness = this_side * prev_side;
if (sideness < 0) {
// Calculate the intersection point.
Vec2d vd = v.cast<double>();
Vec2d p = c.cast<double>() + vd * double(d) / vd.squaredNorm();
point_on_bisector = p.cast<coord_t>();
break;
}
if (sideness == 0) {
// this_point is on the bisector.
assert(prev_side != 0);
assert(this_side == 0);
point_on_bisector = this_point.cast<coord_t>();
break;
Vec2d vd = v.cast<double>();
double ld = v.squaredNorm();
if (ld > sqr(scaled<double>(0.0015))) {
Vec2i64 c = (first_point.cast<int64_t>() + last_point.cast<int64_t>()) / 2;
Vec2i64 prev_point = first_point;
int prev_side = sign(v.dot(prev_point - c));
assert(prev_side != 0);
Point point_on_bisector;
#ifndef NDEBUG
point_on_bisector = { std::numeric_limits<coord_t>::max(), std::numeric_limits<coord_t>::max() };
#endif // NDEBUG
for (auto it = std::next(begin); it != end; ++ it) {
Vec2i64 this_point = it->cast<int64_t>();
int64_t d = v.dot(this_point - c);
int this_side = sign(d);
int sideness = this_side * prev_side;
if (sideness < 0) {
// Calculate the intersection point.
Vec2d p = c.cast<double>() + vd * double(d) / ld;
point_on_bisector = p.cast<coord_t>();
break;
}
if (sideness == 0) {
// this_point is on the bisector.
assert(prev_side != 0);
assert(this_side == 0);
point_on_bisector = this_point.cast<coord_t>();
break;
}
prev_point = this_point;
prev_side = this_side;
}
prev_point = this_point;
prev_side = this_side;
// point_on_bisector must be set
assert(point_on_bisector.x() != std::numeric_limits<coord_t>::max() && point_on_bisector.y() != std::numeric_limits<coord_t>::max());
circle = try_create_circle(*begin, point_on_bisector, *std::prev(end), max_radius);
if (// Use twice the tolerance for fitting the initial circle.
// Early exit if such approximation is grossly inaccurate, thus the tolerance could not be achieved.
circle && ! circle_approximation_sufficient(*circle, begin, end, tolerance * 2))
circle.reset();
}
// point_on_bisector must be set
assert(point_on_bisector.x() != std::numeric_limits<coord_t>::max() && point_on_bisector.y() != std::numeric_limits<coord_t>::max());
circle = try_create_circle(*begin, point_on_bisector, *std::prev(end), max_radius);
if (// Use twice the tolerance for fitting the initial circle.
// Early exit if such approximation is grossly inaccurate, thus the tolerance could not be achieved.
circle && ! circle_approximation_sufficient(*circle, begin, end, tolerance * 2))
circle.reset();
}
if (circle) {
// Fit the arc between the end points by least squares.
@ -320,13 +323,16 @@ static std::optional<Circle> try_create_circle(const Points::const_iterator begi
std::optional<Vec2d> opt_center = ArcWelder::arc_fit_center_gauss_newton_ls(first_point, last_point,
circle->center.cast<double>(), fpts.begin(), fpts.end(), 5);
if (opt_center) {
circle->center = opt_center->cast<coord_t>();
circle->radius = (circle->radius > 0 ? 1.f : -1.f) * (*opt_center - first_point).norm();
if (circle_approximation_sufficient(*circle, begin, end, tolerance)) {
out = circle;
} else {
//FIXME One may consider adjusting the arc to fit the worst offender as a last effort,
// however Vojtech is not sure whether it is worth it.
// Fitted radius must not be excessively large. If so, it is better to fit with a line segment.
if (const double r2 = (*opt_center - first_point).squaredNorm(); r2 < max_radius * max_radius) {
circle->center = opt_center->cast<coord_t>();
circle->radius = (circle->radius > 0 ? 1.f : -1.f) * sqrt(r2);
if (circle_approximation_sufficient(*circle, begin, end, tolerance)) {
out = circle;
} else {
//FIXME One may consider adjusting the arc to fit the worst offender as a last effort,
// however Vojtech is not sure whether it is worth it.
}
}
}
}