bool
BridgeDetector::detect_angle()
{
if (this->_edges.empty() || this->_anchors.empty()) return false;
/* Outset the bridge expolygon by half the amount we used for detecting anchors;
we'll use this one to clip our test lines and be sure that their endpoints
are inside the anchors and not on their contours leading to false negatives. */
Polygons clip_area;
offset(this->expolygon, &clip_area, +this->extrusion_width/2);
/* we'll now try several directions using a rudimentary visibility check:
bridge in several directions and then sum the length of lines having both
endpoints within anchors */
// we test angles according to configured resolution
std::vector<double> angles;
for (int i = 0; i <= PI/this->resolution; ++i)
angles.push_back(i * this->resolution);
// we also test angles of each bridge contour
{
Polygons pp = this->expolygon;
for (Polygons::const_iterator p = pp.begin(); p != pp.end(); ++p) {
Lines lines = p->lines();
for (Lines::const_iterator line = lines.begin(); line != lines.end(); ++line)
angles.push_back(line->direction());
}
}
/* we also test angles of each open supporting edge
(this finds the optimal angle for C-shaped supports) */
for (Polylines::const_iterator edge = this->_edges.begin(); edge != this->_edges.end(); ++edge) {
if (edge->first_point().coincides_with(edge->last_point())) continue;
angles.push_back(Line(edge->first_point(), edge->last_point()).direction());
}
// remove duplicates
double min_resolution = PI/180.0; // 1 degree
std::sort(angles.begin(), angles.end());
for (size_t i = 1; i < angles.size(); ++i) {
if (xd::Geometry::directions_parallel(angles[i], angles[i-1], min_resolution)) {
angles.erase(angles.begin() + i);
--i;
}
}
/* compare first value with last one and remove the greatest one (PI)
in case they are parallel (PI, 0) */
if (xd::Geometry::directions_parallel(angles.front(), angles.back(), min_resolution))
angles.pop_back();
BridgeDirectionComparator bdcomp(this->extrusion_width);
double line_increment = this->extrusion_width;
bool have_coverage = false;
for (std::vector<double>::const_iterator angle = angles.begin(); angle != angles.end(); ++angle) {
Polygons my_clip_area = clip_area;
ExPolygons my_anchors = this->_anchors;
// rotate everything - the center point doesn't matter
for (Polygons::iterator it = my_clip_area.begin(); it != my_clip_area.end(); ++it)
it->rotate(-*angle, Point(0,0));
for (ExPolygons::iterator it = my_anchors.begin(); it != my_anchors.end(); ++it)
it->rotate(-*angle, Point(0,0));
// generate lines in this direction
BoundingBox bb;
for (ExPolygons::const_iterator it = my_anchors.begin(); it != my_anchors.end(); ++it)
bb.merge((Points)*it);
Lines lines;
for (coord_t y = bb.min.y; y <= bb.max.y; y += line_increment)
lines.push_back(Line(Point(bb.min.x, y), Point(bb.max.x, y)));
Lines clipped_lines;
intersection(lines, my_clip_area, &clipped_lines);
// remove any line not having both endpoints within anchors
for (size_t i = 0; i < clipped_lines.size(); ++i) {
Line &line = clipped_lines[i];
if (!xd::Geometry::contains(my_anchors, line.a)
|| !xd::Geometry::contains(my_anchors, line.b)) {
clipped_lines.erase(clipped_lines.begin() + i);
--i;
}
}
std::vector<double> lengths;
double total_length = 0;
for (Lines::const_iterator line = clipped_lines.begin(); line != clipped_lines.end(); ++line) {
double len = line->length();
lengths.push_back(len);
total_length += len;
}
if (total_length) have_coverage = true;
// sum length of bridged lines
bdcomp.dir_coverage[*angle] = total_length;
/* The following produces more correct results in some cases and more broken in others.
TODO: investigate, as it looks more reliable than line clipping. */
// $directions_coverage{$angle} = sum(map $_->area, @{$self->coverage($angle)}) // 0;
// max length of bridged lines
bdcomp.dir_avg_length[*angle] = !lengths.empty()
? *std::max_element(lengths.begin(), lengths.end())
: 0;
}
// if no direction produced coverage, then there's no bridge direction
if (!have_coverage) return false;
// sort directions by score
std::sort(angles.begin(), angles.end(), bdcomp);
this->angle = angles.front();
if (this->angle >= PI) this->angle -= PI;
// #ifdef SLIC3R_DEBUG
// printf(" Optimal infill angle is %d degrees\n", (int)Slic3r::Geometry::rad2deg(this->angle));
// #endif
return true;
}
inline void polygons_rotate(Polygons &polys, double angle)
{
for (Polygons::iterator p = polys.begin(); p != polys.end(); ++p)
p->rotate(angle);
}
void
BridgeDetector::coverage(double angle, Polygons* coverage) const
{
// Clone our expolygon and rotate it so that we work with vertical lines.
ExPolygon expolygon = this->expolygon;
expolygon.rotate(PI/2.0 - angle, Point(0,0));
/* Outset the bridge expolygon by half the amount we used for detecting anchors;
we'll use this one to generate our trapezoids and be sure that their vertices
are inside the anchors and not on their contours leading to false negatives. */
ExPolygons grown;
offset(expolygon, &grown, this->extrusion_width/2.0);
// Compute trapezoids according to a vertical orientation
Polygons trapezoids;
for (ExPolygons::const_iterator it = grown.begin(); it != grown.end(); ++it)
it->get_trapezoids2(&trapezoids, PI/2.0);
// get anchors, convert them to Polygons and rotate them too
Polygons anchors;
for (ExPolygons::const_iterator anchor = this->_anchors.begin(); anchor != this->_anchors.end(); ++anchor) {
Polygons pp = *anchor;
for (Polygons::iterator p = pp.begin(); p != pp.end(); ++p)
p->rotate(PI/2.0 - angle, Point(0,0));
anchors.insert(anchors.end(), pp.begin(), pp.end());
}
Polygons covered;
for (Polygons::const_iterator trapezoid = trapezoids.begin(); trapezoid != trapezoids.end(); ++trapezoid) {
Lines lines = trapezoid->lines();
Lines supported;
intersection(lines, anchors, &supported);
// not nice, we need a more robust non-numeric check
for (size_t i = 0; i < supported.size(); ++i) {
if (supported[i].length() < this->extrusion_width) {
supported.erase(supported.begin() + i);
i--;
}
}
if (supported.size() >= 2) covered.push_back(*trapezoid);
}
// merge trapezoids and rotate them back
Polygons _coverage;
union_(covered, &_coverage);
for (Polygons::iterator p = _coverage.begin(); p != _coverage.end(); ++p)
p->rotate(-(PI/2.0 - angle), Point(0,0));
// intersect trapezoids with actual bridge area to remove extra margins
// and append it to result
intersection(_coverage, this->expolygon, coverage);
/*
if (0) {
my @lines = map @{$_->lines}, @$trapezoids;
$_->rotate(-(PI/2 - $angle), [0,0]) for @lines;
require "Slic3r/SVG.pm";
Slic3r::SVG::output(
"coverage_" . rad2deg($angle) . ".svg",
expolygons => [$self->expolygon],
green_expolygons => $self->_anchors,
red_expolygons => $coverage,
lines => \@lines,
);
}
*/
}