void
PerimeterGenerator::process()
{
// other perimeters
this->_mm3_per_mm = this->perimeter_flow.mm3_per_mm();
coord_t pwidth = this->perimeter_flow.scaled_width();
coord_t pspacing = this->perimeter_flow.scaled_spacing();
// external perimeters
this->_ext_mm3_per_mm = this->ext_perimeter_flow.mm3_per_mm();
coord_t ext_pwidth = this->ext_perimeter_flow.scaled_width();
coord_t ext_pspacing = this->ext_perimeter_flow.scaled_spacing();
coord_t ext_pspacing2 = this->ext_perimeter_flow.scaled_spacing(this->perimeter_flow);
// overhang perimeters
this->_mm3_per_mm_overhang = this->overhang_flow.mm3_per_mm();
// solid infill
coord_t ispacing = this->solid_infill_flow.scaled_spacing();
coord_t gap_area_threshold = pwidth * pwidth;
// Calculate the minimum required spacing between two adjacent traces.
// This should be equal to the nominal flow spacing but we experiment
// with some tolerance in order to avoid triggering medial axis when
// some squishing might work. Loops are still spaced by the entire
// flow spacing; this only applies to collapsing parts.
// For ext_min_spacing we use the ext_pspacing calculated for two adjacent
// external loops (which is the correct way) instead of using ext_pspacing2
// which is the spacing between external and internal, which is not correct
// and would make the collapsing (thus the details resolution) dependent on
// internal flow which is unrelated.
coord_t min_spacing = pspacing * (1 - INSET_OVERLAP_TOLERANCE);
coord_t ext_min_spacing = ext_pspacing * (1 - INSET_OVERLAP_TOLERANCE);
// prepare grown lower layer slices for overhang detection
if (this->lower_slices != NULL && this->config->overhangs) {
// We consider overhang any part where the entire nozzle diameter is not supported by the
// lower layer, so we take lower slices and offset them by half the nozzle diameter used
// in the current layer
double nozzle_diameter = this->print_config->nozzle_diameter.get_at(this->config->perimeter_extruder-1);
this->_lower_slices_p = offset(*this->lower_slices, scale_(+nozzle_diameter/2));
}
// we need to process each island separately because we might have different
// extra perimeters for each one
for (Surfaces::const_iterator surface = this->slices->surfaces.begin();
surface != this->slices->surfaces.end(); ++surface) {
// detect how many perimeters must be generated for this island
signed short loop_number = this->config->perimeters + surface->extra_perimeters;
loop_number--; // 0-indexed loops
Polygons gaps;
Polygons last = surface->expolygon.simplify_p(SCALED_RESOLUTION);
if (loop_number >= 0) { // no loops = -1
std::vector<PerimeterGeneratorLoops> contours(loop_number+1); // depth => loops
std::vector<PerimeterGeneratorLoops> holes(loop_number+1); // depth => loops
Polylines thin_walls;
// we loop one time more than needed in order to find gaps after the last perimeter was applied
for (signed short i = 0; i <= loop_number+1; ++i) { // outer loop is 0
Polygons offsets;
if (i == 0) {
// the minimum thickness of a single loop is:
// ext_width/2 + ext_spacing/2 + spacing/2 + width/2
if (this->config->thin_walls) {
offsets = offset2(
last,
-(ext_pwidth/2 + ext_min_spacing/2 - 1),
+(ext_min_spacing/2 - 1)
);
} else {
offsets = offset(last, -ext_pwidth/2);
}
// look for thin walls
if (this->config->thin_walls) {
Polygons diffpp = diff(
last,
offset(offsets, +ext_pwidth/2),
true // medial axis requires non-overlapping geometry
);
// the following offset2 ensures almost nothing in @thin_walls is narrower than $min_width
// (actually, something larger than that still may exist due to mitering or other causes)
coord_t min_width = ext_pwidth / 2;
ExPolygons expp = offset2_ex(diffpp, -min_width/2, +min_width/2);
// the maximum thickness of our thin wall area is equal to the minimum thickness of a single loop
Polylines pp;
for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
ex->medial_axis(ext_pwidth + ext_pspacing2, min_width, &pp);
double threshold = ext_pwidth * 2;
for (Polylines::const_iterator p = pp.begin(); p != pp.end(); ++p) {
if (p->length() > threshold) {
thin_walls.push_back(*p);
}
}
#ifdef DEBUG
printf(" %zu thin walls detected\n", thin_walls.size());
#endif
/*
if (false) {
require "Slic3r/SVG.pm";
Slic3r::SVG::output(
"medial_axis.svg",
no_arrows => 1,
#expolygons => \@expp,
polylines => \@thin_walls,
);
}
*/
}
} else {
coord_t distance = (i == 1) ? ext_pspacing2 : pspacing;
if (this->config->thin_walls) {
offsets = offset2(
last,
-(distance + min_spacing/2 - 1),
+(min_spacing/2 - 1)
);
} else {
offsets = offset(
last,
-distance
);
}
// look for gaps
if (this->config->gap_fill_speed.value > 0 && this->config->fill_density.value > 0) {
// not using safety offset here would "detect" very narrow gaps
// (but still long enough to escape the area threshold) that gap fill
// won't be able to fill but we'd still remove from infill area
ExPolygons diff_expp = diff_ex(
offset(last, -0.5*distance),
offset(offsets, +0.5*distance + 10) // safety offset
);
for (ExPolygons::const_iterator ex = diff_expp.begin(); ex != diff_expp.end(); ++ex) {
if (fabs(ex->area()) >= gap_area_threshold) {
Polygons pp = *ex;
gaps.insert(gaps.end(), pp.begin(), pp.end());
}
}
}
}
if (offsets.empty()) break;
if (i > loop_number) break; // we were only looking for gaps this time
last = offsets;
for (Polygons::const_iterator polygon = offsets.begin(); polygon != offsets.end(); ++polygon) {
PerimeterGeneratorLoop loop(*polygon, i);
loop.is_contour = polygon->is_counter_clockwise();
if (loop.is_contour) {
contours[i].push_back(loop);
} else {
holes[i].push_back(loop);
}
}
}
// nest loops: holes first
for (signed short d = 0; d <= loop_number; ++d) {
PerimeterGeneratorLoops &holes_d = holes[d];
// loop through all holes having depth == d
for (signed short i = 0; i < holes_d.size(); ++i) {
const PerimeterGeneratorLoop &loop = holes_d[i];
// find the hole loop that contains this one, if any
for (signed short t = d+1; t <= loop_number; ++t) {
for (signed short j = 0; j < holes[t].size(); ++j) {
PerimeterGeneratorLoop &candidate_parent = holes[t][j];
if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
candidate_parent.children.push_back(loop);
holes_d.erase(holes_d.begin() + i);
--i;
goto NEXT_LOOP;
}
}
}
// if no hole contains this hole, find the contour loop that contains it
for (signed short t = loop_number; t >= 0; --t) {
for (signed short j = 0; j < contours[t].size(); ++j) {
PerimeterGeneratorLoop &candidate_parent = contours[t][j];
if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
candidate_parent.children.push_back(loop);
holes_d.erase(holes_d.begin() + i);
--i;
goto NEXT_LOOP;
}
}
}
NEXT_LOOP: ;
}
}
// nest contour loops
for (signed short d = loop_number; d >= 1; --d) {
PerimeterGeneratorLoops &contours_d = contours[d];
// loop through all contours having depth == d
for (signed short i = 0; i < contours_d.size(); ++i) {
const PerimeterGeneratorLoop &loop = contours_d[i];
// find the contour loop that contains it
for (signed short t = d-1; t >= 0; --t) {
for (signed short j = 0; j < contours[t].size(); ++j) {
PerimeterGeneratorLoop &candidate_parent = contours[t][j];
if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
candidate_parent.children.push_back(loop);
contours_d.erase(contours_d.begin() + i);
--i;
goto NEXT_CONTOUR;
}
}
}
NEXT_CONTOUR: ;
}
}
// at this point, all loops should be in contours[0]
ExtrusionEntityCollection entities = this->_traverse_loops(contours.front(), thin_walls);
// if brim will be printed, reverse the order of perimeters so that
// we continue inwards after having finished the brim
// TODO: add test for perimeter order
if (this->config->external_perimeters_first
|| (this->layer_id == 0 && this->print_config->brim_width.value > 0))
entities.reverse();
// append perimeters for this slice as a collection
if (!entities.empty())
this->loops->append(entities);
}
// fill gaps
if (!gaps.empty()) {
/*
if (false) {
require "Slic3r/SVG.pm";
Slic3r::SVG::output(
"gaps.svg",
expolygons => union_ex(\@gaps),
);
}
*/
// where $pwidth < thickness < 2*$pspacing, infill with width = 2*$pwidth
// where 0.1*$pwidth < thickness < $pwidth, infill with width = 1*$pwidth
std::vector<PerimeterGeneratorGapSize> gap_sizes;
gap_sizes.push_back(PerimeterGeneratorGapSize(pwidth, 2*pspacing, 2*pwidth));
gap_sizes.push_back(PerimeterGeneratorGapSize(0.1*pwidth, pwidth, 1*pwidth));
for (std::vector<PerimeterGeneratorGapSize>::const_iterator gap_size = gap_sizes.begin();
gap_size != gap_sizes.end(); ++gap_size) {
ExtrusionEntityCollection gap_fill = this->_fill_gaps(gap_size->min,
gap_size->max, unscale(gap_size->width), gaps);
this->gap_fill->append(gap_fill.entities);
// Make sure we don't infill narrow parts that are already gap-filled
// (we only consider this surface's gaps to reduce the diff() complexity).
// Growing actual extrusions ensures that gaps not filled by medial axis
// are not subtracted from fill surfaces (they might be too short gaps
// that medial axis skips but infill might join with other infill regions
// and use zigzag).
coord_t dist = gap_size->width/2;
Polygons filled;
for (ExtrusionEntitiesPtr::const_iterator it = gap_fill.entities.begin();
it != gap_fill.entities.end(); ++it) {
Polygons f;
offset((*it)->as_polyline(), &f, dist);
filled.insert(filled.end(), f.begin(), f.end());
}
last = diff(last, filled);
gaps = diff(gaps, filled); // prevent more gap fill here
}
}
// create one more offset to be used as boundary for fill
// we offset by half the perimeter spacing (to get to the actual infill boundary)
// and then we offset back and forth by half the infill spacing to only consider the
// non-collapsing regions
coord_t inset = 0;
if (loop_number == 0) {
// one loop
inset += ext_pspacing2/2;
} else if (loop_number > 0) {
// two or more loops
inset += pspacing/2;
}
// only apply infill overlap if we actually have one perimeter
if (inset > 0)
inset -= this->config->get_abs_value("infill_overlap", inset + ispacing/2);
{
ExPolygons expp = union_ex(last);
// simplify infill contours according to resolution
Polygons pp;
for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
ex->simplify_p(SCALED_RESOLUTION, &pp);
// collapse too narrow infill areas
coord_t min_perimeter_infill_spacing = ispacing * (1 - INSET_OVERLAP_TOLERANCE);
expp = offset2_ex(
pp,
-inset -min_perimeter_infill_spacing/2,
+min_perimeter_infill_spacing/2
);
// append infill areas to fill_surfaces
for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
this->fill_surfaces->surfaces.push_back(Surface(stInternal, *ex)); // use a bogus surface type
}
}
}
