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Remove spikes from glyph shape

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This commit is contained in:
Filip Sykala - NTB T15p 2023-01-26 08:04:44 +01:00
parent 8f09c3ac82
commit badbe9ddba
3 changed files with 200 additions and 24 deletions
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212
src/libslic3r/Emboss.cpp
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@ -67,24 +67,189 @@ void visualize_heal(const std::string& svg_filepath, const ExPolygons &expolygon
const Points pts_2x2({Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)});
const Points pts_3x3({Point(-1, -1), Point(1, -1), Point(1, 1), Point(-1, 1)});
// Reduce number of Points in polygons with respect to flatness
// Flatness is area that could be modified
void simplify(Polygon &polygon, float flatness);
void simplify(Polygons &polygons, float flatness);
struct SpikeDesc
{
// cosinus of max spike angle
double cos_angle; // speed up to skip acos
// Half of Wanted bevel size
double half_bevel;
SpikeDesc(double bevel_size) {
// create min angle given by spike_length
// Use it as minimal height of 1 pixel base spike
double length = 6; // has to be smaller than count of heal iteration
double angle = 2. * atan2(length, .5); // [rad]
cos_angle = std::fabs(cos(angle));
// When remove spike this angle is set.
// Value must be grater than min_angle
half_bevel = bevel_size / 2;
}
};
void priv::simplify(Polygon &polygon, float flatness) {
polygon.douglas_peucker(flatness);
// Remove long sharp corners aka spikes
// by adding points to bevel tip of spikes - Not printable parts
// Try to not modify long sides of spike and add points on it's side
void remove_spikes(Polygon &polygon, const SpikeDesc &spike_desc);
void remove_spikes(Polygons &polygons, const SpikeDesc &spike_desc);
void remove_spikes(ExPolygons &expolygons, const SpikeDesc &spike_desc);
};
#include <Geometry.hpp>
void priv::remove_spikes(Polygon &polygon, const SpikeDesc &spike_desc)
{
enum class Type {
add, // Move with point B on A-side and add new point on C-side
move, // Only move with point B
erase // left only points A and C without move
};
struct SpikeHeal
{
Type type;
size_t index;
Point b;
Point add;
};
using SpikeHeals = std::vector<SpikeHeal>;
SpikeHeals heals;
size_t count = polygon.size();
if (count < 3)
return;
const Point *ptr_a = &polygon[count - 2];
const Point *ptr_b = &polygon[count - 1];
for (const Point &c : polygon) {
const Point &a = *ptr_a;
const Point &b = *ptr_b;
ScopeGuard sg([&ptr_a, &ptr_b, &c]() {
// prepare for next loop
ptr_a = ptr_b;
ptr_b = &c;
});
// calc sides
Point ba = a - b;
Point bc = c - b;
Vec2d ba_f = ba.cast<double>();
Vec2d bc_f = bc.cast<double>();
double dot_product = ba_f.dot(bc_f);
// sqrt together after multiplication save one sqrt
double ba_size_sq = ba_f.squaredNorm();
double bc_size_sq = bc_f.squaredNorm();
double norm = sqrt(ba_size_sq * bc_size_sq);
double cos_angle = dot_product / norm;
// small angle are around 1 --> cos(0) = 1
if (cos_angle < spike_desc.cos_angle)
continue;
SpikeHeal heal;
heal.index = &b - &polygon.points.front();
// has to be in range <-1, 1>
// Due to preccission of floating point number could be sligtly out of range
if (cos_angle > 1.)
cos_angle = 1.;
if (cos_angle < -1.)
cos_angle = -1.;
// Current Spike angle
double angle = acos(cos_angle);
double wanted_size = spike_desc.half_bevel / cos(angle / 2.);
double wanted_size_sq = wanted_size * wanted_size;
bool is_ba_short = ba_size_sq < wanted_size_sq;
bool is_bc_short = bc_size_sq < wanted_size_sq;
auto a_side = [&b, &ba_f, &ba_size_sq, &wanted_size]() {
Vec2d ab_norm = ba_f / sqrt(ba_size_sq);
return b + (wanted_size * ab_norm).cast<coord_t>();
};
auto c_side = [&b, &bc_f, &bc_size_sq, &wanted_size]() {
Vec2d bc_norm = bc_f / sqrt(bc_size_sq);
return b + (wanted_size * bc_norm).cast<coord_t>();
};
if (is_ba_short && is_bc_short) {
// remove short spike
heal.type = Type::erase;
} else if (is_ba_short){
// move point B on C-side
heal.type = Type::move;
heal.b = c_side();
} else if (is_bc_short) {
// move point B on A-side
heal.type = Type::move;
heal.b = a_side();
} else {
// move point B on A-side and add point on C-side
heal.type = Type::add;
heal.b = a_side();
heal.add = c_side();
}
heals.push_back(heal);
}
void priv::simplify(Polygons &polygons, float flatness) {
if (heals.empty())
return;
// sort index from high to low
if (heals.front().index == (count - 1))
std::rotate(heals.begin(), heals.begin()+1, heals.end());
std::reverse(heals.begin(), heals.end());
int extend = 0;
int curr_extend = 0;
for (const SpikeHeal &h : heals)
switch (h.type) {
case Type::add:
++curr_extend;
if (extend < curr_extend)
extend = curr_extend;
break;
case Type::erase:
--curr_extend;
}
Points &pts = polygon.points;
if (extend > 0)
pts.reserve(pts.size() + extend);
for (const SpikeHeal &h : heals) {
switch (h.type) {
case Type::add:
pts[h.index] = h.b;
pts.insert(pts.begin() + h.index+1, h.add);
break;
case Type::erase:
pts.erase(pts.begin() + h.index);
break;
case Type::move:
pts[h.index] = h.b;
break;
default: break;
}
}
}
void priv::remove_spikes(Polygons &polygons, const SpikeDesc &spike_desc)
{
for (Polygon &polygon : polygons)
simplify(polygon, flatness);
// simplification could ceate empty polygon
remove_spikes(polygon, spike_desc);
remove_bad(polygons);
}
void priv::remove_spikes(ExPolygons &expolygons, const SpikeDesc &spike_desc)
{
for (ExPolygon &expolygon : expolygons) {
remove_spikes(expolygon.contour, spike_desc);
remove_spikes(expolygon.holes, spike_desc);
}
remove_bad(expolygons);
}
bool priv::is_valid(const FontFile &font, unsigned int index) {
if (font.data == nullptr) return false;
if (font.data->empty()) return false;
@ -380,7 +545,8 @@ bool priv::remove_self_intersections(ExPolygons &shape, unsigned max_iteration)
return false;
}
ExPolygons Emboss::heal_shape(const Polygons &shape) {
ExPolygons Emboss::heal_shape(const Polygons &shape, double precision)
{
// When edit this code check that font 'ALIENATE.TTF' and glyph 'i' still work
// fix of self intersections
// http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Functions/SimplifyPolygon.htm
@ -388,6 +554,14 @@ ExPolygons Emboss::heal_shape(const Polygons &shape) {
const double clean_distance = 1.415; // little grater than sqrt(2)
ClipperLib::CleanPolygons(paths, clean_distance);
Polygons polygons = to_polygons(paths);
polygons.erase(std::remove_if(polygons.begin(), polygons.end(), [](const Polygon &p) { return p.size() < 3; }), polygons.end());
// use douglas peucker to reduce amount of used points
for (Polygon &polygon : polygons)
polygon.douglas_peucker(precision);
priv::SpikeDesc spike(precision);
priv::remove_spikes(polygons, spike);
// Do not remove all duplicits but do it better way
// Overlap all duplicit points by rectangle 3x3
@ -405,6 +579,12 @@ ExPolygons Emboss::heal_shape(const Polygons &shape) {
// https://docs.microsoft.com/en-us/typography/opentype/spec/ttch01
// https://developer.apple.com/fonts/TrueType-Reference-Manual/RM01/Chap1.html
ExPolygons res = Slic3r::union_ex(polygons, ClipperLib::pftNonZero);
priv::remove_spikes(polygons, spike);
double min_area = precision * precision;
priv::remove_small_islands(res, min_area);
heal_shape(res);
return res;
}
@ -438,6 +618,8 @@ bool priv::heal_dupl_inter(ExPolygons &shape, unsigned max_iteration)
{
if (shape.empty()) return true;
//priv::visualize_heal("C:/data/temp/heal_prev.svg", shape);
// create loop permanent memory
Polygons holes;
Points intersections;
@ -622,18 +804,10 @@ std::optional<Glyph> priv::get_glyph(const stbtt_fontinfo &font_info, int unicod
// change outer cw to ccw and inner ccw to cw order
std::reverse(pts.begin(), pts.end());
{ // use douglas peucker to reduce amount of used points
pts.push_back(pts.front());
pts = MultiPoint::_douglas_peucker(pts, flatness);
pts.pop_back();
if (pts.size() < 3)
continue;
}
glyph_polygons.emplace_back(pts);
}
if (!glyph_polygons.empty())
glyph.shape = Emboss::heal_shape(glyph_polygons);
glyph.shape = Emboss::heal_shape(glyph_polygons, flatness / SHAPE_SCALE);
return glyph;
}

6
src/libslic3r/Emboss.hpp
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@ -154,11 +154,13 @@ namespace Emboss
ExPolygons text2shapes(FontFileWithCache &font, const char *text, const FontProp &font_prop, std::function<bool()> was_canceled = nullptr);
/// <summary>
/// Fix intersections and self intersections in polygons glyph shape
/// Fix duplicit points and self intersections in polygons.
/// Also try to reduce amount of points and remove useless polygon parts
/// </summary>
/// <param name="shape">Input shape to heal</param>
/// <param name="precision">Define wanted precision of shape after heal</param>
/// <returns>Healed shapes</returns>
ExPolygons heal_shape(const Polygons &shape);
ExPolygons heal_shape(const Polygons &shape, double precision);
/// <summary>
/// NOTE: call Slic3r::union_ex before this call

2
tests/libslic3r/test_emboss.cpp
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@ -203,7 +203,7 @@ ExPolygons heal_and_check(const Polygons &polygons)
Points polygons_points = to_points(polygons);
Points duplicits_prev = collect_duplicates(polygons_points);
ExPolygons shape = Emboss::heal_shape(polygons);
ExPolygons shape = Emboss::heal_shape(polygons, 10);
// Is default shape for unhealabled shape?
bool is_default_shape =