void
BridgeDetector::unsupported_edges(double angle, Polylines* unsupported) const
{
// get bridge edges (both contour and holes)
Polylines bridge_edges;
{
Polygons pp = this->expolygon;
bridge_edges.insert(bridge_edges.end(), pp.begin(), pp.end()); // this uses split_at_first_point()
}
// get unsupported edges
Polygons grown_lower;
offset(this->lower_slices, &grown_lower, +this->extrusion_width);
Polylines _unsupported;
diff(bridge_edges, grown_lower, &_unsupported);
/* Split into individual segments and filter out edges parallel to the bridging angle
TODO: angle tolerance should probably be based on segment length and flow width,
so that we build supports whenever there's a chance that at least one or two bridge
extrusions would be anchored within such length (i.e. a slightly non-parallel bridging
direction might still benefit from anchors if long enough) */
double angle_tolerance = PI / 180.0 * 5.0;
for (Polylines::const_iterator polyline = _unsupported.begin(); polyline != _unsupported.end(); ++polyline) {
Lines lines = polyline->lines();
for (Lines::const_iterator line = lines.begin(); line != lines.end(); ++line) {
if (!xd::Geometry::directions_parallel(line->direction(), angle))
unsupported->push_back(*line);
}
}
/*
if (0) {
require "Slic3r/SVG.pm";
Slic3r::SVG::output(
"unsupported_" . rad2deg($angle) . ".svg",
expolygons => [$self->expolygon],
green_expolygons => $self->_anchors,
red_expolygons => union_ex($grown_lower),
no_arrows => 1,
polylines => \@bridge_edges,
red_polylines => $unsupported,
);
}
*/
}
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;
}
