orcaslicer/src/libslic3r/SLA/SLAPad.cpp
2019-10-09 14:59:09 +02:00

695 lines
24 KiB
C++

#include "SLAPad.hpp"
#include "SLABoilerPlate.hpp"
#include "SLASpatIndex.hpp"
#include "ConcaveHull.hpp"
#include "boost/log/trivial.hpp"
#include "SLABoostAdapter.hpp"
#include "ClipperUtils.hpp"
#include "Tesselate.hpp"
#include "MTUtils.hpp"
// For debugging:
// #include <fstream>
// #include <libnest2d/tools/benchmark.h>
#include "SVG.hpp"
#include "I18N.hpp"
#include <boost/log/trivial.hpp>
//! macro used to mark string used at localization,
//! return same string
#define L(s) Slic3r::I18N::translate(s)
namespace Slic3r { namespace sla {
namespace {
/// This function will return a triangulation of a sheet connecting an upper
/// and a lower plate given as input polygons. It will not triangulate the
/// plates themselves only the sheet. The caller has to specify the lower and
/// upper z levels in world coordinates as well as the offset difference
/// between the sheets. If the lower_z_mm is higher than upper_z_mm or the
/// offset difference is negative, the resulting triangle orientation will be
/// reversed.
///
/// IMPORTANT: This is not a universal triangulation algorithm. It assumes
/// that the lower and upper polygons are offsetted versions of the same
/// original polygon. In general, it assumes that one of the polygons is
/// completely inside the other. The offset difference is the reference
/// distance from the inner polygon's perimeter to the outer polygon's
/// perimeter. The real distance will be variable as the clipper offset has
/// different strategies (rounding, etc...). This algorithm should have
/// O(2n + 3m) complexity where n is the number of upper vertices and m is the
/// number of lower vertices.
Contour3D walls(
const Polygon &lower,
const Polygon &upper,
double lower_z_mm,
double upper_z_mm,
double offset_difference_mm,
ThrowOnCancel thr = [] {})
{
Contour3D ret;
if(upper.points.size() < 3 || lower.size() < 3) return ret;
// The concept of the algorithm is relatively simple. It will try to find
// the closest vertices from the upper and the lower polygon and use those
// as starting points. Then it will create the triangles sequentially using
// an edge from the upper polygon and a vertex from the lower or vice versa,
// depending on the resulting triangle's quality.
// The quality is measured by a scalar value. So far it looks like it is
// enough to derive it from the slope of the triangle's two edges connecting
// the upper and the lower part. A reference slope is calculated from the
// height and the offset difference.
// Offset in the index array for the ceiling
const auto offs = upper.points.size();
// Shorthand for the vertex arrays
auto& upts = upper.points, &lpts = lower.points;
auto& rpts = ret.points; auto& ind = ret.indices;
// If the Z levels are flipped, or the offset difference is negative, we
// will interpret that as the triangles normals should be inverted.
bool inverted = upper_z_mm < lower_z_mm || offset_difference_mm < 0;
// Copy the points into the mesh, convert them from 2D to 3D
rpts.reserve(upts.size() + lpts.size());
ind.reserve(2 * upts.size() + 2 * lpts.size());
for (auto &p : upts)
rpts.emplace_back(unscaled(p.x()), unscaled(p.y()), upper_z_mm);
for (auto &p : lpts)
rpts.emplace_back(unscaled(p.x()), unscaled(p.y()), lower_z_mm);
// Create pointing indices into vertex arrays. u-upper, l-lower
size_t uidx = 0, lidx = offs, unextidx = 1, lnextidx = offs + 1;
// Simple squared distance calculation.
auto distfn = [](const Vec3d& p1, const Vec3d& p2) {
auto p = p1 - p2; return p.transpose() * p;
};
// We need to find the closest point on lower polygon to the first point on
// the upper polygon. These will be our starting points.
double distmin = std::numeric_limits<double>::max();
for(size_t l = lidx; l < rpts.size(); ++l) {
thr();
double d = distfn(rpts[l], rpts[uidx]);
if(d < distmin) { lidx = l; distmin = d; }
}
// Set up lnextidx to be ahead of lidx in cyclic mode
lnextidx = lidx + 1;
if(lnextidx == rpts.size()) lnextidx = offs;
// This will be the flip switch to toggle between upper and lower triangle
// creation mode
enum class Proceed {
UPPER, // A segment from the upper polygon and one vertex from the lower
LOWER // A segment from the lower polygon and one vertex from the upper
} proceed = Proceed::UPPER;
// Flags to help evaluating loop termination.
bool ustarted = false, lstarted = false;
// The variables for the fitness values, one for the actual and one for the
// previous.
double current_fit = 0, prev_fit = 0;
// Every triangle of the wall has two edges connecting the upper plate with
// the lower plate. From the length of these two edges and the zdiff we
// can calculate the momentary squared offset distance at a particular
// position on the wall. The average of the differences from the reference
// (squared) offset distance will give us the driving fitness value.
const double offsdiff2 = std::pow(offset_difference_mm, 2);
const double zdiff2 = std::pow(upper_z_mm - lower_z_mm, 2);
// Mark the current vertex iterator positions. If the iterators return to
// the same position, the loop can be terminated.
size_t uendidx = uidx, lendidx = lidx;
do { thr(); // check throw if canceled
prev_fit = current_fit;
switch(proceed) { // proceed depending on the current state
case Proceed::UPPER:
if(!ustarted || uidx != uendidx) { // there are vertices remaining
// Get the 3D vertices in order
const Vec3d& p_up1 = rpts[uidx];
const Vec3d& p_low = rpts[lidx];
const Vec3d& p_up2 = rpts[unextidx];
// Calculate fitness: the average of the two connecting edges
double a = offsdiff2 - (distfn(p_up1, p_low) - zdiff2);
double b = offsdiff2 - (distfn(p_up2, p_low) - zdiff2);
current_fit = (std::abs(a) + std::abs(b)) / 2;
if(current_fit > prev_fit) { // fit is worse than previously
proceed = Proceed::LOWER;
} else { // good to go, create the triangle
inverted
? ind.emplace_back(int(unextidx), int(lidx), int(uidx))
: ind.emplace_back(int(uidx), int(lidx), int(unextidx));
// Increment the iterators, rotate if necessary
++uidx; ++unextidx;
if(unextidx == offs) unextidx = 0;
if(uidx == offs) uidx = 0;
ustarted = true; // mark the movement of the iterators
// so that the comparison to uendidx can be made correctly
}
} else proceed = Proceed::LOWER;
break;
case Proceed::LOWER:
// Mode with lower segment, upper vertex. Same structure:
if(!lstarted || lidx != lendidx) {
const Vec3d& p_low1 = rpts[lidx];
const Vec3d& p_low2 = rpts[lnextidx];
const Vec3d& p_up = rpts[uidx];
double a = offsdiff2 - (distfn(p_up, p_low1) - zdiff2);
double b = offsdiff2 - (distfn(p_up, p_low2) - zdiff2);
current_fit = (std::abs(a) + std::abs(b)) / 2;
if(current_fit > prev_fit) {
proceed = Proceed::UPPER;
} else {
inverted
? ind.emplace_back(int(uidx), int(lnextidx), int(lidx))
: ind.emplace_back(int(lidx), int(lnextidx), int(uidx));
++lidx; ++lnextidx;
if(lnextidx == rpts.size()) lnextidx = offs;
if(lidx == rpts.size()) lidx = offs;
lstarted = true;
}
} else proceed = Proceed::UPPER;
break;
} // end of switch
} while(!ustarted || !lstarted || uidx != uendidx || lidx != lendidx);
return ret;
}
// Same as walls() but with identical higher and lower polygons.
Contour3D inline straight_walls(const Polygon &plate,
double lo_z,
double hi_z,
ThrowOnCancel thr)
{
return walls(plate, plate, lo_z, hi_z, .0 /*offset_diff*/, thr);
}
// Function to cut tiny connector cavities for a given polygon. The input poly
// will be offsetted by "padding" and small rectangle shaped cavities will be
// inserted along the perimeter in every "stride" distance. The stick rectangles
// will have a with about "stick_width". The input dimensions are in world
// measure, not the scaled clipper units.
void breakstick_holes(Points& pts,
double padding,
double stride,
double stick_width,
double penetration)
{
if(stride <= EPSILON || stick_width <= EPSILON || padding <= EPSILON)
return;
// SVG svg("bridgestick_plate.svg");
// svg.draw(poly);
// The connector stick will be a small rectangle with dimensions
// stick_width x (penetration + padding) to have some penetration
// into the input polygon.
Points out;
out.reserve(2 * pts.size()); // output polygon points
// stick bottom and right edge dimensions
double sbottom = scaled(stick_width);
double sright = scaled(penetration + padding);
// scaled stride distance
double sstride = scaled(stride);
double t = 0;
// process pairs of vertices as an edge, start with the last and
// first point
for (size_t i = pts.size() - 1, j = 0; j < pts.size(); i = j, ++j) {
// Get vertices and the direction vectors
const Point &a = pts[i], &b = pts[j];
Vec2d dir = b.cast<double>() - a.cast<double>();
double nrm = dir.norm();
dir /= nrm;
Vec2d dirp(-dir(Y), dir(X));
// Insert start point
out.emplace_back(a);
// dodge the start point, do not make sticks on the joins
while (t < sbottom) t += sbottom;
double tend = nrm - sbottom;
while (t < tend) { // insert the stick on the polygon perimeter
// calculate the stick rectangle vertices and insert them
// into the output.
Point p1 = a + (t * dir).cast<coord_t>();
Point p2 = p1 + (sright * dirp).cast<coord_t>();
Point p3 = p2 + (sbottom * dir).cast<coord_t>();
Point p4 = p3 + (sright * -dirp).cast<coord_t>();
out.insert(out.end(), {p1, p2, p3, p4});
// continue along the perimeter
t += sstride;
}
t = t - nrm;
// Insert edge endpoint
out.emplace_back(b);
}
// move the new points
out.shrink_to_fit();
pts.swap(out);
}
template<class...Args>
ExPolygons breakstick_holes(const ExPolygons &input, Args...args)
{
ExPolygons ret = input;
for (ExPolygon &p : ret) {
breakstick_holes(p.contour.points, args...);
for (auto &h : p.holes) breakstick_holes(h.points, args...);
}
return ret;
}
static inline coord_t get_waffle_offset(const PadConfig &c)
{
return scaled(c.brim_size_mm + c.wing_distance());
}
static inline double get_merge_distance(const PadConfig &c)
{
return 2. * (1.8 * c.wall_thickness_mm) + c.max_merge_dist_mm;
}
// Part of the pad configuration that is used for 3D geometry generation
struct PadConfig3D {
double thickness, height, wing_height, slope;
explicit PadConfig3D(const PadConfig &cfg2d)
: thickness{cfg2d.wall_thickness_mm}
, height{cfg2d.full_height()}
, wing_height{cfg2d.wall_height_mm}
, slope{cfg2d.wall_slope}
{}
inline double bottom_offset() const
{
return (thickness + wing_height) / std::tan(slope);
}
};
// Outer part of the skeleton is used to generate the waffled edges of the pad.
// Inner parts will not be waffled or offsetted. Inner parts are only used if
// pad is generated around the object and correspond to holes and inner polygons
// in the model blueprint.
struct PadSkeleton { ExPolygons inner, outer; };
PadSkeleton divide_blueprint(const ExPolygons &bp)
{
ClipperLib::PolyTree ptree = union_pt(bp);
PadSkeleton ret;
ret.inner.reserve(size_t(ptree.Total()));
ret.outer.reserve(size_t(ptree.Total()));
for (ClipperLib::PolyTree::PolyNode *node : ptree.Childs) {
ExPolygon poly(ClipperPath_to_Slic3rPolygon(node->Contour));
for (ClipperLib::PolyTree::PolyNode *child : node->Childs) {
if (child->IsHole()) {
poly.holes.emplace_back(
ClipperPath_to_Slic3rPolygon(child->Contour));
traverse_pt_unordered(child->Childs, &ret.inner);
}
else traverse_pt_unordered(child, &ret.inner);
}
ret.outer.emplace_back(poly);
}
return ret;
}
// A helper class for storing polygons and maintaining a spatial index of their
// bounding boxes.
class Intersector {
BoxIndex m_index;
ExPolygons m_polys;
public:
// Add a new polygon to the index
void add(const ExPolygon &ep)
{
m_polys.emplace_back(ep);
m_index.insert(BoundingBox{ep}, unsigned(m_index.size()));
}
// Check an arbitrary polygon for intersection with the indexed polygons
bool intersects(const ExPolygon &poly)
{
// Create a suitable query bounding box.
auto bb = poly.contour.bounding_box();
std::vector<BoxIndexEl> qres = m_index.query(bb, BoxIndex::qtIntersects);
// Now check intersections on the actual polygons (not just the boxes)
bool is_overlap = false;
auto qit = qres.begin();
while (!is_overlap && qit != qres.end())
is_overlap = is_overlap || poly.overlaps(m_polys[(qit++)->second]);
return is_overlap;
}
};
// This dummy intersector to implement the "force pad everywhere" feature
struct DummyIntersector
{
inline void add(const ExPolygon &) {}
inline bool intersects(const ExPolygon &) { return true; }
};
template<class _Intersector>
class _AroundPadSkeleton : public PadSkeleton
{
// A spatial index used to be able to efficiently find intersections of
// support polygons with the model polygons.
_Intersector m_intersector;
public:
_AroundPadSkeleton(const ExPolygons &support_blueprint,
const ExPolygons &model_blueprint,
const PadConfig & cfg,
ThrowOnCancel thr)
{
// We need to merge the support and the model contours in a special
// way in which the model contours have to be substracted from the
// support contours. The pad has to have a hole in which the model can
// fit perfectly (thus the substraction -- diff_ex). Also, the pad has
// to be eliminated from areas where there is no need for a pad, due
// to missing supports.
add_supports_to_index(support_blueprint);
auto model_bp_offs =
offset_ex(model_blueprint,
scaled<float>(cfg.embed_object.object_gap_mm),
ClipperLib::jtMiter, 1);
ExPolygons fullcvh =
wafflized_concave_hull(support_blueprint, model_bp_offs, cfg, thr);
auto model_bp_sticks =
breakstick_holes(model_bp_offs, cfg.embed_object.object_gap_mm,
cfg.embed_object.stick_stride_mm,
cfg.embed_object.stick_width_mm,
cfg.embed_object.stick_penetration_mm);
ExPolygons fullpad = diff_ex(fullcvh, model_bp_sticks);
remove_redundant_parts(fullpad);
PadSkeleton divided = divide_blueprint(fullpad);
outer = std::move(divided.outer);
inner = std::move(divided.inner);
}
private:
// Add the support blueprint to the search index to be queried later
void add_supports_to_index(const ExPolygons &supp_bp)
{
for (auto &ep : supp_bp) m_intersector.add(ep);
}
// Create the wafflized pad around all object in the scene. This pad doesnt
// have any holes yet.
ExPolygons wafflized_concave_hull(const ExPolygons &supp_bp,
const ExPolygons &model_bp,
const PadConfig &cfg,
ThrowOnCancel thr)
{
auto allin = reserve_vector<ExPolygon>(supp_bp.size() + model_bp.size());
for (auto &ep : supp_bp) allin.emplace_back(ep.contour);
for (auto &ep : model_bp) allin.emplace_back(ep.contour);
ConcaveHull cchull{allin, get_merge_distance(cfg), thr};
return offset_waffle_style_ex(cchull, get_waffle_offset(cfg));
}
// To remove parts of the pad skeleton which do not host any supports
void remove_redundant_parts(ExPolygons &parts)
{
auto endit = std::remove_if(parts.begin(), parts.end(),
[this](const ExPolygon &p) {
return !m_intersector.intersects(p);
});
parts.erase(endit, parts.end());
}
};
using AroundPadSkeleton = _AroundPadSkeleton<Intersector>;
using BrimPadSkeleton = _AroundPadSkeleton<DummyIntersector>;
class BelowPadSkeleton : public PadSkeleton
{
public:
BelowPadSkeleton(const ExPolygons &support_blueprint,
const ExPolygons &model_blueprint,
const PadConfig & cfg,
ThrowOnCancel thr)
{
outer.reserve(support_blueprint.size() + model_blueprint.size());
for (auto &ep : support_blueprint) outer.emplace_back(ep.contour);
for (auto &ep : model_blueprint) outer.emplace_back(ep.contour);
ConcaveHull ochull{outer, get_merge_distance(cfg), thr};
outer = offset_waffle_style_ex(ochull, get_waffle_offset(cfg));
}
};
// Offset the contour only, leave the holes untouched
template<class...Args>
ExPolygon offset_contour_only(const ExPolygon &poly, coord_t delta, Args...args)
{
ExPolygons tmp = offset_ex(poly.contour, float(delta), args...);
if (tmp.empty()) return {};
Polygons holes = poly.holes;
for (auto &h : holes) h.reverse();
tmp = diff_ex(to_polygons(tmp), holes);
if (tmp.empty()) return {};
return tmp.front();
}
bool add_cavity(Contour3D &pad, ExPolygon &top_poly, const PadConfig3D &cfg,
ThrowOnCancel thr)
{
auto logerr = []{BOOST_LOG_TRIVIAL(error)<<"Could not create pad cavity";};
double wing_distance = cfg.wing_height / std::tan(cfg.slope);
coord_t delta_inner = -scaled(cfg.thickness + wing_distance);
coord_t delta_middle = -scaled(cfg.thickness);
ExPolygon inner_base = offset_contour_only(top_poly, delta_inner);
ExPolygon middle_base = offset_contour_only(top_poly, delta_middle);
if (inner_base.empty() || middle_base.empty()) { logerr(); return false; }
ExPolygons pdiff = diff_ex(top_poly, middle_base.contour);
if (pdiff.size() != 1) { logerr(); return false; }
top_poly = pdiff.front();
double z_min = -cfg.wing_height, z_max = 0;
double offset_difference = -wing_distance;
pad.merge(walls(inner_base.contour, middle_base.contour, z_min, z_max,
offset_difference, thr));
pad.merge(triangulate_expolygon_3d(inner_base, z_min, NORMALS_UP));
return true;
}
Contour3D create_outer_pad_geometry(const ExPolygons & skeleton,
const PadConfig3D &cfg,
ThrowOnCancel thr)
{
Contour3D ret;
for (const ExPolygon &pad_part : skeleton) {
ExPolygon top_poly{pad_part};
ExPolygon bottom_poly =
offset_contour_only(pad_part, -scaled(cfg.bottom_offset()));
if (bottom_poly.empty()) continue;
double z_min = -cfg.height, z_max = 0;
ret.merge(walls(top_poly.contour, bottom_poly.contour, z_max, z_min,
cfg.bottom_offset(), thr));
if (cfg.wing_height > 0. && add_cavity(ret, top_poly, cfg, thr))
z_max = -cfg.wing_height;
for (auto &h : bottom_poly.holes)
ret.merge(straight_walls(h, z_max, z_min, thr));
ret.merge(triangulate_expolygon_3d(bottom_poly, z_min, NORMALS_DOWN));
ret.merge(triangulate_expolygon_3d(top_poly, NORMALS_UP));
}
return ret;
}
Contour3D create_inner_pad_geometry(const ExPolygons & skeleton,
const PadConfig3D &cfg,
ThrowOnCancel thr)
{
Contour3D ret;
double z_max = 0., z_min = -cfg.height;
for (const ExPolygon &pad_part : skeleton) {
ret.merge(straight_walls(pad_part.contour, z_max, z_min,thr));
for (auto &h : pad_part.holes)
ret.merge(straight_walls(h, z_max, z_min, thr));
ret.merge(triangulate_expolygon_3d(pad_part, z_min, NORMALS_DOWN));
ret.merge(triangulate_expolygon_3d(pad_part, z_max, NORMALS_UP));
}
return ret;
}
Contour3D create_pad_geometry(const PadSkeleton &skelet,
const PadConfig & cfg,
ThrowOnCancel thr)
{
#ifndef NDEBUG
SVG svg("pad_skeleton.svg");
svg.draw(skelet.outer, "green");
svg.draw(skelet.inner, "blue");
svg.Close();
#endif
PadConfig3D cfg3d(cfg);
return create_outer_pad_geometry(skelet.outer, cfg3d, thr)
.merge(create_inner_pad_geometry(skelet.inner, cfg3d, thr));
}
Contour3D create_pad_geometry(const ExPolygons &supp_bp,
const ExPolygons &model_bp,
const PadConfig & cfg,
ThrowOnCancel thr)
{
PadSkeleton skelet;
if (cfg.embed_object.enabled) {
if (cfg.embed_object.everywhere)
skelet = BrimPadSkeleton(supp_bp, model_bp, cfg, thr);
else
skelet = AroundPadSkeleton(supp_bp, model_bp, cfg, thr);
} else
skelet = BelowPadSkeleton(supp_bp, model_bp, cfg, thr);
return create_pad_geometry(skelet, cfg, thr);
}
} // namespace
void pad_blueprint(const TriangleMesh & mesh,
ExPolygons & output,
const std::vector<float> &heights,
ThrowOnCancel thrfn)
{
if (mesh.empty()) return;
TriangleMeshSlicer slicer(&mesh);
auto out = reserve_vector<ExPolygons>(heights.size());
slicer.slice(heights, 0.f, &out, thrfn);
size_t count = 0;
for(auto& o : out) count += o.size();
// Unification is expensive, a simplify also speeds up the pad generation
auto tmp = reserve_vector<ExPolygon>(count);
for(ExPolygons& o : out)
for(ExPolygon& e : o) {
auto&& exss = e.simplify(scaled<double>(0.1));
for(ExPolygon& ep : exss) tmp.emplace_back(std::move(ep));
}
ExPolygons utmp = union_ex(tmp);
for(auto& o : utmp) {
auto&& smp = o.simplify(scaled<double>(0.1));
output.insert(output.end(), smp.begin(), smp.end());
}
}
void pad_blueprint(const TriangleMesh &mesh,
ExPolygons & output,
float h,
float layerh,
ThrowOnCancel thrfn)
{
float gnd = float(mesh.bounding_box().min(Z));
std::vector<float> slicegrid = grid(gnd, gnd + h, layerh);
pad_blueprint(mesh, output, slicegrid, thrfn);
}
void create_pad(const ExPolygons &sup_blueprint,
const ExPolygons &model_blueprint,
TriangleMesh & out,
const PadConfig & cfg,
ThrowOnCancel thr)
{
Contour3D t = create_pad_geometry(sup_blueprint, model_blueprint, cfg, thr);
out.merge(mesh(std::move(t)));
}
std::string PadConfig::validate() const
{
static const double constexpr MIN_BRIM_SIZE_MM = .1;
if (brim_size_mm < MIN_BRIM_SIZE_MM ||
bottom_offset() > brim_size_mm + wing_distance() ||
get_waffle_offset(*this) <= MIN_BRIM_SIZE_MM)
return L("Pad brim size is too small for the current configuration.");
return "";
}
}} // namespace Slic3r::sla