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Use exact intergral in SupportSpotsGenerator.

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Previously a numerical integration for ObjectPart was performed.
Now it is calculated exactly over triangles. The code has
also been refactored to enable unit testing.
This commit is contained in:
Martin Šach 2023-09-25 12:26:04 +02:00 committed by SachCZ
parent 11273b29ac
commit ea69deef24
1 changed files with 105 additions and 122 deletions
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227
src/libslic3r/SupportSpotsGenerator.cpp
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@ -268,29 +268,6 @@ float get_flow_width(const LayerRegion *region, ExtrusionRole role)
return region->flow(FlowRole::frPerimeter).width();
}
std::vector<ExtrusionLine> to_short_lines(const ExtrusionEntity *e, float length_limit)
{
assert(!e->is_collection());
Polyline pl = e->as_polyline();
std::vector<ExtrusionLine> lines;
lines.reserve(pl.points.size() * 1.5f);
for (int point_idx = 0; point_idx < int(pl.points.size()) - 1; ++point_idx) {
Vec2f start = unscaled(pl.points[point_idx]).cast<float>();
Vec2f next = unscaled(pl.points[point_idx + 1]).cast<float>();
Vec2f v = next - start; // vector from next to current
float dist_to_next = v.norm();
v.normalize();
int lines_count = int(std::ceil(dist_to_next / length_limit));
float step_size = dist_to_next / lines_count;
for (int i = 0; i < lines_count; ++i) {
Vec2f a(start + v * (i * step_size));
Vec2f b(start + v * ((i + 1) * step_size));
lines.emplace_back(a, b, (a-b).norm(), e);
}
}
return lines;
}
float estimate_curled_up_height(
float distance, float curvature, float layer_height, float flow_width, float prev_line_curled_height, Params params)
{
@ -513,7 +490,48 @@ public:
float sticking_second_moment_of_area_covariance_accumulator{};
bool connected_to_bed = false;
ObjectPart() = default;
ObjectPart(
const std::vector<const ExtrusionEntityCollection*>& extrusion_collections,
const bool connected_to_bed,
const coordf_t print_head_z,
const coordf_t layer_height,
const std::optional<Polygons>& brim
) {
if (connected_to_bed) {
this->connected_to_bed = true;
}
const auto bottom_z = print_head_z - layer_height;
const auto center_z = print_head_z - layer_height / 2;
for (const ExtrusionEntityCollection* collection : extrusion_collections) {
if (collection->empty()) {
continue;
}
const Polygons polygons{collection->polygons_covered_by_width()};
const Integrals integrals{polygons};
const float volume = integrals.area * layer_height;
this->volume += volume;
this->volume_centroid_accumulator += to_3d(integrals.x_i, center_z * integrals.area) / integrals.area * volume; // TODO check that it is correct
if (this->connected_to_bed) {
this->sticking_area += integrals.area;
this->sticking_centroid_accumulator += to_3d(integrals.x_i, bottom_z * integrals.area); // TODO check that it layer height should be added
this->sticking_second_moment_of_area_accumulator += integrals.x_i_squared;
this->sticking_second_moment_of_area_covariance_accumulator += integrals.xy;
}
}
if (brim) {
Integrals integrals{*brim};
this->sticking_area += integrals.area;
this->sticking_centroid_accumulator += to_3d(integrals.x_i, bottom_z * integrals.area);
this->sticking_second_moment_of_area_accumulator += integrals.x_i_squared;
this->sticking_second_moment_of_area_covariance_accumulator += integrals.xy;
}
}
void add(const ObjectPart &other)
{
@ -678,117 +696,67 @@ public:
}
};
// return new object part and actual area covered by extrusions
std::tuple<ObjectPart, float> build_object_part_from_slice(const size_t &slice_idx, const Layer *layer, const Params& params)
{
ObjectPart new_object_part;
float area_covered_by_extrusions = 0;
const LayerSlice& slice = layer->lslices_ex.at(slice_idx);
auto add_extrusions_to_object = [&new_object_part, &area_covered_by_extrusions, &params](const ExtrusionEntity *e,
const LayerRegion *region) {
float flow_width = get_flow_width(region, e->role());
const Layer *l = region->layer();
float slice_z = l->slice_z;
float height = l->height;
std::vector<ExtrusionLine> lines = to_short_lines(e, 5.0);
for (const ExtrusionLine &line : lines) {
float volume = line.len * height * flow_width * PI / 4.0f;
area_covered_by_extrusions += line.len * flow_width;
new_object_part.volume += volume;
new_object_part.volume_centroid_accumulator += to_3d(Vec2f((line.a + line.b) / 2.0f), slice_z) * volume;
if (int(l->id()) == params.raft_layers_count) { // layer attached on bed/raft
new_object_part.connected_to_bed = true;
float sticking_area = line.len * flow_width;
new_object_part.sticking_area += sticking_area;
Vec2f middle = Vec2f((line.a + line.b) / 2.0f);
new_object_part.sticking_centroid_accumulator += sticking_area * to_3d(middle, slice_z);
// Bottom infill lines can be quite long, and algined, so the middle approximaton used above does not work
Vec2f dir = (line.b - line.a).normalized();
float segment_length = flow_width; // segments of size flow_width
for (float segment_middle_dist = std::min(line.len, segment_length * 0.5f); segment_middle_dist < line.len;
segment_middle_dist += segment_length) {
Vec2f segment_middle = line.a + segment_middle_dist * dir;
new_object_part.sticking_second_moment_of_area_accumulator += segment_length * flow_width *
segment_middle.cwiseProduct(segment_middle);
new_object_part.sticking_second_moment_of_area_covariance_accumulator += segment_length * flow_width *
segment_middle.x() * segment_middle.y();
}
}
}
};
std::vector<const ExtrusionEntityCollection*> gather_extrusions(const LayerSlice& slice, const Layer* layer) {
// TODO reserve might be good, benchmark
std::vector<const ExtrusionEntityCollection*> result;
for (const auto &island : slice.islands) {
const LayerRegion *perimeter_region = layer->get_region(island.perimeters.region());
for (size_t perimeter_idx : island.perimeters) {
for (const ExtrusionEntity *perimeter :
static_cast<const ExtrusionEntityCollection *>(perimeter_region->perimeters().entities[perimeter_idx])->entities) {
add_extrusions_to_object(perimeter, perimeter_region);
}
auto collection = static_cast<const ExtrusionEntityCollection *>(
perimeter_region->perimeters().entities[perimeter_idx]
);
result.push_back(collection);
}
for (const LayerExtrusionRange &fill_range : island.fills) {
const LayerRegion *fill_region = layer->get_region(fill_range.region());
for (size_t fill_idx : fill_range) {
for (const ExtrusionEntity *fill :
static_cast<const ExtrusionEntityCollection *>(fill_region->fills().entities[fill_idx])->entities) {
add_extrusions_to_object(fill, fill_region);
}
auto collection = static_cast<const ExtrusionEntityCollection *>(
fill_region->fills().entities[fill_idx]
);
result.push_back(collection);
}
}
for (size_t thin_fill_idx : island.thin_fills) {
add_extrusions_to_object(perimeter_region->thin_fills().entities[thin_fill_idx], perimeter_region);
const ExtrusionEntityCollection& collection = perimeter_region->thin_fills();
result.push_back(&collection);
}
return result;
}
bool has_brim(const Layer* layer, const Params& params){
return
int(layer->id()) == params.raft_layers_count
&& params.raft_layers_count == 0
&& params.brim_type != BrimType::btNoBrim
&& params.brim_width > 0.0;
}
Polygons get_brim(const ExPolygon& slice_polygon, const BrimType brim_type, const float brim_width) {
// TODO: The algorithm here should take into account that multiple slices may
// have coliding Brim areas and the final brim area is smaller,
// thus has lower adhesion. For now this effect will be neglected.
ExPolygons brim;
if (brim_type == BrimType::btOuterAndInner || brim_type == BrimType::btOuterOnly) {
Polygon brim_hole = slice_polygon.contour;
brim_hole.reverse();
Polygons c = expand(slice_polygon.contour, scale_(brim_width)); // For very small polygons, the expand may result in empty vector, even thought the input is correct.
if (!c.empty()) {
brim.push_back(ExPolygon{c.front(), brim_hole});
}
}
// BRIM HANDLING
if (int(layer->id()) == params.raft_layers_count && params.raft_layers_count == 0 && params.brim_type != BrimType::btNoBrim &&
params.brim_width > 0.0) {
// TODO: The algorithm here should take into account that multiple slices may have coliding Brim areas and the final brim area is
// smaller,
// thus has lower adhesion. For now this effect will be neglected.
ExPolygon slice_poly = layer->lslices[slice_idx];
ExPolygons brim;
if (params.brim_type == BrimType::btOuterAndInner || params.brim_type == BrimType::btOuterOnly) {
Polygon brim_hole = slice_poly.contour;
brim_hole.reverse();
Polygons c = expand(slice_poly.contour, scale_(params.brim_width)); // For very small polygons, the expand may result in empty vector, even thought the input is correct.
if (!c.empty()) {
brim.push_back(ExPolygon{c.front(), brim_hole});
}
}
if (params.brim_type == BrimType::btOuterAndInner || params.brim_type == BrimType::btInnerOnly) {
Polygons brim_contours = slice_poly.holes;
polygons_reverse(brim_contours);
for (const Polygon &brim_contour : brim_contours) {
Polygons brim_holes = shrink({brim_contour}, scale_(params.brim_width));
polygons_reverse(brim_holes);
ExPolygon inner_brim{brim_contour};
inner_brim.holes = brim_holes;
brim.push_back(inner_brim);
}
}
for (const Polygon &poly : to_polygons(brim)) {
Vec2f p0 = unscaled(poly.first_point()).cast<float>();
for (size_t i = 2; i < poly.points.size(); i++) {
Vec2f p1 = unscaled(poly.points[i - 1]).cast<float>();
Vec2f p2 = unscaled(poly.points[i]).cast<float>();
float sign = cross2(p1 - p0, p2 - p1) > 0 ? 1.0f : -1.0f;
auto [area, first_moment_of_area, second_moment_area,
second_moment_of_area_covariance] = compute_moments_of_area_of_triangle(p0, p1, p2);
new_object_part.sticking_area += sign * area;
new_object_part.sticking_centroid_accumulator += sign * Vec3f(first_moment_of_area.x(), first_moment_of_area.y(),
layer->print_z * area);
new_object_part.sticking_second_moment_of_area_accumulator += sign * second_moment_area;
new_object_part.sticking_second_moment_of_area_covariance_accumulator += sign * second_moment_of_area_covariance;
}
if (brim_type == BrimType::btOuterAndInner || brim_type == BrimType::btInnerOnly) {
Polygons brim_contours = slice_polygon.holes;
polygons_reverse(brim_contours);
for (const Polygon &brim_contour : brim_contours) {
Polygons brim_holes = shrink({brim_contour}, scale_(brim_width));
polygons_reverse(brim_holes);
ExPolygon inner_brim{brim_contour};
inner_brim.holes = brim_holes;
brim.push_back(inner_brim);
}
}
return {new_object_part, area_covered_by_extrusions};
return to_polygons(brim);
}
class ActiveObjectParts
@ -862,7 +830,22 @@ std::tuple<SupportPoints, PartialObjects> check_stability(const PrintObject
for (size_t slice_idx = 0; slice_idx < layer->lslices_ex.size(); ++slice_idx) {
const LayerSlice &slice = layer->lslices_ex.at(slice_idx);
auto [new_part, covered_area] = build_object_part_from_slice(slice_idx, layer, params);
const std::vector<const ExtrusionEntityCollection*> extrusion_collections{gather_extrusions(slice, layer)};
const bool connected_to_bed = int(layer->id()) == params.raft_layers_count;
const std::optional<Polygons> brim{
has_brim(layer, params) ?
std::optional{get_brim(layer->lslices[slice_idx], params.brim_type, params.brim_width)} :
std::nullopt
};
ObjectPart new_part{
extrusion_collections,
connected_to_bed,
layer->print_z,
layer->height,
brim
};
const SliceConnection &connection_to_below = precomputed_slices_connections[layer_idx][slice_idx];
#ifdef DETAILED_DEBUG_LOGS