orcaslicer/src/libslic3r/SLA/SLASupportTree.cpp
2019-04-12 10:26:33 +02:00

2296 lines
82 KiB
C++

/**
* In this file we will implement the automatic SLA support tree generation.
*
*/
#include <numeric>
#include "SLASupportTree.hpp"
#include "SLABoilerPlate.hpp"
#include "SLASpatIndex.hpp"
#include "SLABasePool.hpp"
#include <libslic3r/ClipperUtils.hpp>
#include <libslic3r/Model.hpp>
#include <libnest2d/optimizers/nlopt/genetic.hpp>
#include <boost/log/trivial.hpp>
#include <tbb/parallel_for.h>
#include <libslic3r/I18N.hpp>
//! macro used to mark string used at localization,
//! return same string
#define L(s) Slic3r::I18N::translate(s)
/**
* Terminology:
*
* Support point:
* The point on the model surface that needs support.
*
* Pillar:
* A thick column that spans from a support point to the ground and has
* a thick cone shaped base where it touches the ground.
*
* Ground facing support point:
* A support point that can be directly connected with the ground with a pillar
* that does not collide or cut through the model.
*
* Non ground facing support point:
* A support point that cannot be directly connected with the ground (only with
* the model surface).
*
* Head:
* The pinhead that connects to the model surface with the sharp end end
* to a pillar or bridge stick with the dull end.
*
* Headless support point:
* A support point on the model surface for which there is not enough place for
* the head. It is either in a hole or there is some barrier that would collide
* with the head geometry. The headless support point can be ground facing and
* non ground facing as well.
*
* Bridge:
* A stick that connects two pillars or a head with a pillar.
*
* Junction:
* A small ball in the intersection of two or more sticks (pillar, bridge, ...)
*
* CompactBridge:
* A bridge that connects a headless support point with the model surface or a
* nearby pillar.
*/
namespace Slic3r {
namespace sla {
// Compile time configuration value definitions:
// The max Z angle for a normal at which it will get completely ignored.
const double SupportConfig::normal_cutoff_angle = 150.0 * M_PI / 180.0;
// The shortest distance of any support structure from the model surface
const double SupportConfig::safety_distance_mm = 0.5;
const double SupportConfig::max_solo_pillar_height_mm = 15.0;
const double SupportConfig::max_dual_pillar_height_mm = 35.0;
const double SupportConfig::optimizer_rel_score_diff = 1e-6;
const unsigned SupportConfig::optimizer_max_iterations = 1000;
const unsigned SupportConfig::pillar_cascade_neighbors = 3;
const unsigned SupportConfig::max_bridges_on_pillar = 3;
using Coordf = double;
using Portion = std::tuple<double, double>;
inline Portion make_portion(double a, double b) {
return std::make_tuple(a, b);
}
template<class Vec> double distance(const Vec& p) {
return std::sqrt(p.transpose() * p);
}
template<class Vec> double distance(const Vec& pp1, const Vec& pp2) {
auto p = pp2 - pp1;
return distance(p);
}
Contour3D sphere(double rho, Portion portion = make_portion(0.0, 2.0*PI),
double fa=(2*PI/360)) {
Contour3D ret;
// prohibit close to zero radius
if(rho <= 1e-6 && rho >= -1e-6) return ret;
auto& vertices = ret.points;
auto& facets = ret.indices;
// Algorithm:
// Add points one-by-one to the sphere grid and form facets using relative
// coordinates. Sphere is composed effectively of a mesh of stacked circles.
// adjust via rounding to get an even multiple for any provided angle.
double angle = (2*PI / floor(2*PI / fa));
// Ring to be scaled to generate the steps of the sphere
std::vector<double> ring;
for (double i = 0; i < 2*PI; i+=angle) ring.emplace_back(i);
const auto sbegin = size_t(2*std::get<0>(portion)/angle);
const auto send = size_t(2*std::get<1>(portion)/angle);
const size_t steps = ring.size();
const double increment = 1.0 / double(steps);
// special case: first ring connects to 0,0,0
// insert and form facets.
if(sbegin == 0)
vertices.emplace_back(Vec3d(0.0, 0.0, -rho + increment*sbegin*2.0*rho));
auto id = coord_t(vertices.size());
for (size_t i = 0; i < ring.size(); i++) {
// Fixed scaling
const double z = -rho + increment*rho*2.0 * (sbegin + 1.0);
// radius of the circle for this step.
const double r = std::sqrt(std::abs(rho*rho - z*z));
Vec2d b = Eigen::Rotation2Dd(ring[i]) * Eigen::Vector2d(0, r);
vertices.emplace_back(Vec3d(b(0), b(1), z));
if(sbegin == 0)
facets.emplace_back((i == 0) ? Vec3crd(coord_t(ring.size()), 0, 1) :
Vec3crd(id - 1, 0, id));
++ id;
}
// General case: insert and form facets for each step,
// joining it to the ring below it.
for (size_t s = sbegin + 2; s < send - 1; s++) {
const double z = -rho + increment*double(s*2.0*rho);
const double r = std::sqrt(std::abs(rho*rho - z*z));
for (size_t i = 0; i < ring.size(); i++) {
Vec2d b = Eigen::Rotation2Dd(ring[i]) * Eigen::Vector2d(0, r);
vertices.emplace_back(Vec3d(b(0), b(1), z));
auto id_ringsize = coord_t(id - int(ring.size()));
if (i == 0) {
// wrap around
facets.emplace_back(Vec3crd(id - 1, id,
id + coord_t(ring.size() - 1)));
facets.emplace_back(Vec3crd(id - 1, id_ringsize, id));
} else {
facets.emplace_back(Vec3crd(id_ringsize - 1, id_ringsize, id));
facets.emplace_back(Vec3crd(id - 1, id_ringsize - 1, id));
}
id++;
}
}
// special case: last ring connects to 0,0,rho*2.0
// only form facets.
if(send >= size_t(2*PI / angle)) {
vertices.emplace_back(Vec3d(0.0, 0.0, -rho + increment*send*2.0*rho));
for (size_t i = 0; i < ring.size(); i++) {
auto id_ringsize = coord_t(id - int(ring.size()));
if (i == 0) {
// third vertex is on the other side of the ring.
facets.emplace_back(Vec3crd(id - 1, id_ringsize, id));
} else {
auto ci = coord_t(id_ringsize + coord_t(i));
facets.emplace_back(Vec3crd(ci - 1, ci, id));
}
}
}
id++;
return ret;
}
// Down facing cylinder in Z direction with arguments:
// r: radius
// h: Height
// ssteps: how many edges will create the base circle
// sp: starting point
Contour3D cylinder(double r, double h, size_t ssteps, const Vec3d sp = {0,0,0})
{
Contour3D ret;
auto steps = int(ssteps);
auto& points = ret.points;
auto& indices = ret.indices;
points.reserve(2*ssteps);
double a = 2*PI/steps;
Vec3d jp = sp;
Vec3d endp = {sp(X), sp(Y), sp(Z) + h};
// Upper circle points
for(int i = 0; i < steps; ++i) {
double phi = i*a;
double ex = endp(X) + r*std::cos(phi);
double ey = endp(Y) + r*std::sin(phi);
points.emplace_back(ex, ey, endp(Z));
}
// Lower circle points
for(int i = 0; i < steps; ++i) {
double phi = i*a;
double x = jp(X) + r*std::cos(phi);
double y = jp(Y) + r*std::sin(phi);
points.emplace_back(x, y, jp(Z));
}
// Now create long triangles connecting upper and lower circles
indices.reserve(2*ssteps);
auto offs = steps;
for(int i = 0; i < steps - 1; ++i) {
indices.emplace_back(i, i + offs, offs + i + 1);
indices.emplace_back(i, offs + i + 1, i + 1);
}
// Last triangle connecting the first and last vertices
auto last = steps - 1;
indices.emplace_back(0, last, offs);
indices.emplace_back(last, offs + last, offs);
// According to the slicing algorithms, we need to aid them with generating
// a watertight body. So we create a triangle fan for the upper and lower
// ending of the cylinder to close the geometry.
points.emplace_back(jp); size_t ci = points.size() - 1;
for(int i = 0; i < steps - 1; ++i)
indices.emplace_back(i + offs + 1, i + offs, ci);
indices.emplace_back(offs, steps + offs - 1, ci);
points.emplace_back(endp); ci = points.size() - 1;
for(int i = 0; i < steps - 1; ++i)
indices.emplace_back(ci, i, i + 1);
indices.emplace_back(steps - 1, 0, ci);
return ret;
}
struct Head {
Contour3D mesh;
size_t steps = 45;
Vec3d dir = {0, 0, -1};
Vec3d tr = {0, 0, 0};
double r_back_mm = 1;
double r_pin_mm = 0.5;
double width_mm = 2;
double penetration_mm = 0.5;
// For identification purposes. This will be used as the index into the
// container holding the head structures. See SLASupportTree::Impl
long id = -1;
// If there is a pillar connecting to this head, then the id will be set.
long pillar_id = -1;
inline void invalidate() { id = -1; }
inline bool is_valid() const { return id >= 0; }
Head(double r_big_mm,
double r_small_mm,
double length_mm,
double penetration,
Vec3d direction = {0, 0, -1}, // direction (normal to the dull end )
Vec3d offset = {0, 0, 0}, // displacement
const size_t circlesteps = 45):
steps(circlesteps), dir(direction), tr(offset),
r_back_mm(r_big_mm), r_pin_mm(r_small_mm), width_mm(length_mm),
penetration_mm(penetration)
{
// We create two spheres which will be connected with a robe that fits
// both circles perfectly.
// Set up the model detail level
const double detail = 2*PI/steps;
// We don't generate whole circles. Instead, we generate only the
// portions which are visible (not covered by the robe) To know the
// exact portion of the bottom and top circles we need to use some
// rules of tangent circles from which we can derive (using simple
// triangles the following relations:
// The height of the whole mesh
const double h = r_big_mm + r_small_mm + width_mm;
double phi = PI/2 - std::acos( (r_big_mm - r_small_mm) / h );
// To generate a whole circle we would pass a portion of (0, Pi)
// To generate only a half horizontal circle we can pass (0, Pi/2)
// The calculated phi is an offset to the half circles needed to smooth
// the transition from the circle to the robe geometry
auto&& s1 = sphere(r_big_mm, make_portion(0, PI/2 + phi), detail);
auto&& s2 = sphere(r_small_mm, make_portion(PI/2 + phi, PI), detail);
for(auto& p : s2.points) z(p) += h;
mesh.merge(s1);
mesh.merge(s2);
for(size_t idx1 = s1.points.size() - steps, idx2 = s1.points.size();
idx1 < s1.points.size() - 1;
idx1++, idx2++)
{
coord_t i1s1 = coord_t(idx1), i1s2 = coord_t(idx2);
coord_t i2s1 = i1s1 + 1, i2s2 = i1s2 + 1;
mesh.indices.emplace_back(i1s1, i2s1, i2s2);
mesh.indices.emplace_back(i1s1, i2s2, i1s2);
}
auto i1s1 = coord_t(s1.points.size()) - coord_t(steps);
auto i2s1 = coord_t(s1.points.size()) - 1;
auto i1s2 = coord_t(s1.points.size());
auto i2s2 = coord_t(s1.points.size()) + coord_t(steps) - 1;
mesh.indices.emplace_back(i2s2, i2s1, i1s1);
mesh.indices.emplace_back(i1s2, i2s2, i1s1);
// To simplify further processing, we translate the mesh so that the
// last vertex of the pointing sphere (the pinpoint) will be at (0,0,0)
for(auto& p : mesh.points) z(p) -= (h + r_small_mm - penetration_mm);
}
void transform()
{
using Quaternion = Eigen::Quaternion<double>;
// We rotate the head to the specified direction The head's pointing
// side is facing upwards so this means that it would hold a support
// point with a normal pointing straight down. This is the reason of
// the -1 z coordinate
auto quatern = Quaternion::FromTwoVectors(Vec3d{0, 0, -1}, dir);
for(auto& p : mesh.points) p = quatern * p + tr;
}
double fullwidth() const {
return 2 * r_pin_mm + width_mm + 2*r_back_mm - penetration_mm;
}
static double fullwidth(const SupportConfig& cfg) {
return 2 * cfg.head_front_radius_mm + cfg.head_width_mm +
2 * cfg.head_back_radius_mm - cfg.head_penetration_mm;
}
Vec3d junction_point() const {
return tr + ( 2 * r_pin_mm + width_mm + r_back_mm - penetration_mm)*dir;
}
double request_pillar_radius(double radius) const {
const double rmax = r_back_mm;
return radius > 0 && radius < rmax ? radius : rmax;
}
};
struct Junction {
Contour3D mesh;
double r = 1;
size_t steps = 45;
Vec3d pos;
long id = -1;
Junction(const Vec3d& tr, double r_mm, size_t stepnum = 45):
r(r_mm), steps(stepnum), pos(tr)
{
mesh = sphere(r_mm, make_portion(0, PI), 2*PI/steps);
for(auto& p : mesh.points) p += tr;
}
};
struct Pillar {
Contour3D mesh;
Contour3D base;
double r = 1;
size_t steps = 0;
Vec3d endpt;
double height = 0;
long id = -1;
// If the pillar connects to a head, this is the id of that head
bool starts_from_head = true; // Could start from a junction as well
long start_junction_id = -1;
// How many bridges are connected to this pillar
unsigned bridges = 0;
// How many pillars are cascaded with this one
unsigned links = 0;
Pillar(const Vec3d& jp, const Vec3d& endp,
double radius = 1, size_t st = 45):
r(radius), steps(st), endpt(endp), starts_from_head(false)
{
assert(steps > 0);
height = jp(Z) - endp(Z);
if(height > 0) { // Endpoint is below the starting point
// We just create a bridge geometry with the pillar parameters and
// move the data.
Contour3D body = cylinder(radius, height, st, endp);
mesh.points.swap(body.points);
mesh.indices.swap(body.indices);
}
}
Pillar(const Junction& junc, const Vec3d& endp):
Pillar(junc.pos, endp, junc.r, junc.steps){}
Pillar(const Head& head, const Vec3d& endp, double radius = 1):
Pillar(head.junction_point(), endp, head.request_pillar_radius(radius),
head.steps)
{
}
inline Vec3d startpoint() const {
return {endpt(X), endpt(Y), endpt(Z) + height};
}
inline const Vec3d& endpoint() const { return endpt; }
Pillar& add_base(double baseheight = 3, double radius = 2) {
if(baseheight <= 0) return *this;
if(baseheight > height) baseheight = height;
assert(steps >= 0);
auto last = int(steps - 1);
if(radius < r ) radius = r;
double a = 2*PI/steps;
double z = endpt(Z) + baseheight;
for(size_t i = 0; i < steps; ++i) {
double phi = i*a;
double x = endpt(X) + r*std::cos(phi);
double y = endpt(Y) + r*std::sin(phi);
base.points.emplace_back(x, y, z);
}
for(size_t i = 0; i < steps; ++i) {
double phi = i*a;
double x = endpt(X) + radius*std::cos(phi);
double y = endpt(Y) + radius*std::sin(phi);
base.points.emplace_back(x, y, z - baseheight);
}
auto ep = endpt; ep(Z) += baseheight;
base.points.emplace_back(endpt);
base.points.emplace_back(ep);
auto& indices = base.indices;
auto hcenter = int(base.points.size() - 1);
auto lcenter = int(base.points.size() - 2);
auto offs = int(steps);
for(int i = 0; i < last; ++i) {
indices.emplace_back(i, i + offs, offs + i + 1);
indices.emplace_back(i, offs + i + 1, i + 1);
indices.emplace_back(i, i + 1, hcenter);
indices.emplace_back(lcenter, offs + i + 1, offs + i);
}
indices.emplace_back(0, last, offs);
indices.emplace_back(last, offs + last, offs);
indices.emplace_back(hcenter, last, 0);
indices.emplace_back(offs, offs + last, lcenter);
return *this;
}
bool has_base() const { return !base.points.empty(); }
};
// A Bridge between two pillars (with junction endpoints)
struct Bridge {
Contour3D mesh;
double r = 0.8;
long id = -1;
long start_jid = -1;
long end_jid = -1;
// We should reduce the radius a tiny bit to help the convex hull algorithm
Bridge(const Vec3d& j1, const Vec3d& j2,
double r_mm = 0.8, size_t steps = 45):
r(r_mm)
{
using Quaternion = Eigen::Quaternion<double>;
Vec3d dir = (j2 - j1).normalized();
double d = distance(j2, j1);
mesh = cylinder(r, d, steps);
auto quater = Quaternion::FromTwoVectors(Vec3d{0,0,1}, dir);
for(auto& p : mesh.points) p = quater * p + j1;
}
Bridge(const Junction& j1, const Junction& j2, double r_mm = 0.8):
Bridge(j1.pos, j2.pos, r_mm, j1.steps) {}
};
// A bridge that spans from model surface to model surface with small connecting
// edges on the endpoints. Used for headless support points.
struct CompactBridge {
Contour3D mesh;
long id = -1;
CompactBridge(const Vec3d& sp,
const Vec3d& ep,
const Vec3d& n,
double r,
size_t steps = 45)
{
Vec3d startp = sp + r * n;
Vec3d dir = (ep - startp).normalized();
Vec3d endp = ep - r * dir;
Bridge br(startp, endp, r, steps);
mesh.merge(br.mesh);
// now add the pins
double fa = 2*PI/steps;
auto upperball = sphere(r, Portion{PI / 2 - fa, PI}, fa);
for(auto& p : upperball.points) p += startp;
auto lowerball = sphere(r, Portion{0, PI/2 + 2*fa}, fa);
for(auto& p : lowerball.points) p += endp;
mesh.merge(upperball);
mesh.merge(lowerball);
}
};
// A wrapper struct around the base pool (pad)
struct Pad {
TriangleMesh tmesh;
PoolConfig cfg;
double zlevel = 0;
Pad() {}
Pad(const TriangleMesh& object_support_mesh,
const ExPolygons& baseplate,
double ground_level,
const PoolConfig& pcfg) :
cfg(pcfg),
zlevel(ground_level +
(sla::get_pad_fullheight(pcfg) - sla::get_pad_elevation(pcfg)) )
{
ExPolygons basep;
cfg.throw_on_cancel();
// The 0.1f is the layer height with which the mesh is sampled and then
// the layers are unified into one vector of polygons.
base_plate(object_support_mesh, basep,
float(cfg.min_wall_height_mm + cfg.min_wall_thickness_mm),
0.1f, pcfg.throw_on_cancel);
for(auto& bp : baseplate) basep.emplace_back(bp);
create_base_pool(basep, tmesh, cfg);
tmesh.translate(0, 0, float(zlevel));
}
bool empty() const { return tmesh.facets_count() == 0; }
};
// The minimum distance for two support points to remain valid.
static const double /*constexpr*/ D_SP = 0.1;
enum { // For indexing Eigen vectors as v(X), v(Y), v(Z) instead of numbers
X, Y, Z
};
// Calculate the normals for the selected points (from 'points' set) on the
// mesh. This will call squared distance for each point.
PointSet normals(const PointSet& points,
const EigenMesh3D& mesh,
double eps = 0.05, // min distance from edges
std::function<void()> throw_on_cancel = [](){},
const std::vector<unsigned>& selected_points = {});
inline Vec2d to_vec2(const Vec3d& v3) {
return {v3(X), v3(Y)};
}
bool operator==(const SpatElement& e1, const SpatElement& e2) {
return e1.second == e2.second;
}
// Clustering a set of points by the given distance.
ClusteredPoints cluster(const std::vector<unsigned>& indices,
std::function<Vec3d(unsigned)> pointfn,
double dist,
unsigned max_points);
ClusteredPoints cluster(const PointSet& points,
double dist,
unsigned max_points);
ClusteredPoints cluster(
const std::vector<unsigned>& indices,
std::function<Vec3d(unsigned)> pointfn,
std::function<bool(const SpatElement&, const SpatElement&)> predicate,
unsigned max_points);
// This class will hold the support tree meshes with some additional bookkeeping
// as well. Various parts of the support geometry are stored separately and are
// merged when the caller queries the merged mesh. The merged result is cached
// for fast subsequent delivery of the merged mesh which can be quite complex.
// An object of this class will be used as the result type during the support
// generation algorithm. Parts will be added with the appropriate methods such
// as add_head or add_pillar which forwards the constructor arguments and fills
// the IDs of these substructures. The IDs are basically indices into the arrays
// of the appropriate type (heads, pillars, etc...). One can later query e.g. a
// pillar for a specific head...
//
// The support pad is considered an auxiliary geometry and is not part of the
// merged mesh. It can be retrieved using a dedicated method (pad())
class SLASupportTree::Impl {
std::map<unsigned, Head> m_heads;
std::vector<Pillar> m_pillars;
std::vector<Junction> m_junctions;
std::vector<Bridge> m_bridges;
std::vector<CompactBridge> m_compact_bridges;
Controller m_ctl;
Pad m_pad;
mutable TriangleMesh meshcache; mutable bool meshcache_valid = false;
mutable double model_height = 0; // the full height of the model
public:
double ground_level = 0;
Impl() = default;
inline Impl(const Controller& ctl): m_ctl(ctl) {}
const Controller& ctl() const { return m_ctl; }
template<class...Args> Head& add_head(unsigned id, Args&&... args) {
auto el = m_heads.emplace(std::piecewise_construct,
std::forward_as_tuple(id),
std::forward_as_tuple(std::forward<Args>(args)...));
el.first->second.id = id;
meshcache_valid = false;
return el.first->second;
}
template<class...Args> Pillar& add_pillar(unsigned headid, Args&&... args) {
auto it = m_heads.find(headid);
assert(it != m_heads.end());
Head& head = it->second;
m_pillars.emplace_back(head, std::forward<Args>(args)...);
Pillar& pillar = m_pillars.back();
pillar.id = long(m_pillars.size() - 1);
head.pillar_id = pillar.id;
pillar.start_junction_id = head.id;
pillar.starts_from_head = true;
meshcache_valid = false;
return m_pillars.back();
}
void increment_bridges(const Pillar& pillar) {
assert(pillar.id >= 0 && size_t(pillar.id) < m_pillars.size());
if(pillar.id >= 0 && size_t(pillar.id) < m_pillars.size())
m_pillars[size_t(pillar.id)].bridges++;
}
void increment_links(const Pillar& pillar) {
assert(pillar.id >= 0 && size_t(pillar.id) < m_pillars.size());
if(pillar.id >= 0 && size_t(pillar.id) < m_pillars.size())
m_pillars[size_t(pillar.id)].links++;
}
template<class...Args> Pillar& add_pillar(Args&&...args)
{
m_pillars.emplace_back(std::forward<Args>(args)...);
Pillar& pillar = m_pillars.back();
pillar.id = long(m_pillars.size() - 1);
pillar.starts_from_head = false;
meshcache_valid = false;
return m_pillars.back();
}
const Head& pillar_head(long pillar_id) const {
assert(pillar_id >= 0 && pillar_id < long(m_pillars.size()));
const Pillar& p = m_pillars[size_t(pillar_id)];
assert(p.starts_from_head && p.start_junction_id >= 0);
auto it = m_heads.find(unsigned(p.start_junction_id));
assert(it != m_heads.end());
return it->second;
}
const Pillar& head_pillar(unsigned headid) const {
auto it = m_heads.find(headid);
assert(it != m_heads.end());
const Head& h = it->second;
assert(h.pillar_id >= 0 && h.pillar_id < long(m_pillars.size()));
return pillar(h.pillar_id);
}
template<class...Args> const Junction& add_junction(Args&&... args) {
m_junctions.emplace_back(std::forward<Args>(args)...);
m_junctions.back().id = long(m_junctions.size() - 1);
meshcache_valid = false;
return m_junctions.back();
}
template<class...Args> const Bridge& add_bridge(Args&&... args) {
m_bridges.emplace_back(std::forward<Args>(args)...);
m_bridges.back().id = long(m_bridges.size() - 1);
meshcache_valid = false;
return m_bridges.back();
}
template<class...Args>
const CompactBridge& add_compact_bridge(Args&&...args) {
m_compact_bridges.emplace_back(std::forward<Args>(args)...);
m_compact_bridges.back().id = long(m_compact_bridges.size() - 1);
meshcache_valid = false;
return m_compact_bridges.back();
}
const std::map<unsigned, Head>& heads() const { return m_heads; }
Head& head(unsigned idx) {
meshcache_valid = false;
auto it = m_heads.find(idx);
assert(it != m_heads.end());
return it->second;
}
const std::vector<Pillar>& pillars() const { return m_pillars; }
const std::vector<Bridge>& bridges() const { return m_bridges; }
const std::vector<Junction>& junctions() const { return m_junctions; }
const std::vector<CompactBridge>& compact_bridges() const {
return m_compact_bridges;
}
template<class T> inline const Pillar& pillar(T id) const {
static_assert(std::is_integral<T>::value, "Invalid index type");
assert(id >= 0 && id < m_pillars.size() &&
id < std::numeric_limits<size_t>::max());
return m_pillars[size_t(id)];
}
const Pad& create_pad(const TriangleMesh& object_supports,
const ExPolygons& baseplate,
const PoolConfig& cfg) {
m_pad = Pad(object_supports, baseplate, ground_level, cfg);
return m_pad;
}
void remove_pad() {
m_pad = Pad();
}
const Pad& pad() const { return m_pad; }
// WITHOUT THE PAD!!!
const TriangleMesh& merged_mesh() const {
if(meshcache_valid) return meshcache;
Contour3D merged;
for(auto& headel : heads()) {
if(m_ctl.stopcondition()) break;
if(headel.second.is_valid())
merged.merge(headel.second.mesh);
}
for(auto& stick : pillars()) {
if(m_ctl.stopcondition()) break;
merged.merge(stick.mesh);
merged.merge(stick.base);
}
for(auto& j : junctions()) {
if(m_ctl.stopcondition()) break;
merged.merge(j.mesh);
}
for(auto& cb : compact_bridges()) {
if(m_ctl.stopcondition()) break;
merged.merge(cb.mesh);
}
for(auto& bs : bridges()) {
if(m_ctl.stopcondition()) break;
merged.merge(bs.mesh);
}
if(m_ctl.stopcondition()) {
// In case of failure we have to return an empty mesh
meshcache = TriangleMesh();
return meshcache;
}
meshcache = mesh(merged);
// TODO: Is this necessary?
//meshcache.repair();
BoundingBoxf3&& bb = meshcache.bounding_box();
model_height = bb.max(Z) - bb.min(Z);
meshcache_valid = true;
return meshcache;
}
// WITH THE PAD
double full_height() const {
if(merged_mesh().empty() && !pad().empty())
return get_pad_fullheight(pad().cfg);
double h = mesh_height();
if(!pad().empty()) h += sla::get_pad_elevation(pad().cfg);
return h;
}
// WITHOUT THE PAD!!!
double mesh_height() const {
if(!meshcache_valid) merged_mesh();
return model_height;
}
};
// This function returns the position of the centroid in the input 'clust'
// vector of point indices.
template<class DistFn>
long cluster_centroid(const ClusterEl& clust,
std::function<Vec3d(size_t)> pointfn,
DistFn df)
{
switch(clust.size()) {
case 0: /* empty cluster */ return -1;
case 1: /* only one element */ return 0;
case 2: /* if two elements, there is no center */ return 0;
default: ;
}
// The function works by calculating for each point the average distance
// from all the other points in the cluster. We create a selector bitmask of
// the same size as the cluster. The bitmask will have two true bits and
// false bits for the rest of items and we will loop through all the
// permutations of the bitmask (combinations of two points). Get the
// distance for the two points and add the distance to the averages.
// The point with the smallest average than wins.
// The complexity should be O(n^2) but we will mostly apply this function
// for small clusters only (cca 3 elements)
std::vector<bool> sel(clust.size(), false); // create full zero bitmask
std::fill(sel.end() - 2, sel.end(), true); // insert the two ones
std::vector<double> avgs(clust.size(), 0.0); // store the average distances
do {
std::array<size_t, 2> idx;
for(size_t i = 0, j = 0; i < clust.size(); i++) if(sel[i]) idx[j++] = i;
double d = df(pointfn(clust[idx[0]]),
pointfn(clust[idx[1]]));
// add the distance to the sums for both associated points
for(auto i : idx) avgs[i] += d;
// now continue with the next permutation of the bitmask with two 1s
} while(std::next_permutation(sel.begin(), sel.end()));
// Divide by point size in the cluster to get the average (may be redundant)
for(auto& a : avgs) a /= clust.size();
// get the lowest average distance and return the index
auto minit = std::min_element(avgs.begin(), avgs.end());
return long(minit - avgs.begin());
}
inline Vec3d dirv(const Vec3d& startp, const Vec3d& endp) {
return (endp - startp).normalized();
}
class SLASupportTree::Algorithm {
const SupportConfig& m_cfg;
const EigenMesh3D& m_mesh;
const std::vector<SupportPoint>& m_support_pts;
using PtIndices = std::vector<unsigned>;
PtIndices m_iheads; // support points with pinhead
PtIndices m_iheadless; // headless support points
// supp. pts. connecting to model: point index and the ray hit data
std::vector<std::pair<unsigned, EigenMesh3D::hit_result>> m_iheads_onmodel;
// normals for support points from model faces.
PointSet m_support_nmls;
// Clusters of points which can reach the ground directly and can be
// bridged to one central pillar
std::vector<PtIndices> m_pillar_clusters;
// This algorithm uses the Impl class as its output stream. It will be
// filled gradually with support elements (heads, pillars, bridges, ...)
using Result = SLASupportTree::Impl;
Result& m_result;
// support points in Eigen/IGL format
PointSet m_points;
// throw if canceled: It will be called many times so a shorthand will
// come in handy.
ThrowOnCancel m_thr;
// A spatial index to easily find strong pillars to connect to.
SpatIndex m_pillar_index;
inline double ray_mesh_intersect(const Vec3d& s,
const Vec3d& dir)
{
return m_mesh.query_ray_hit(s, dir).distance();
}
// This function will test if a future pinhead would not collide with the
// model geometry. It does not take a 'Head' object because those are
// created after this test. Parameters: s: The touching point on the model
// surface. dir: This is the direction of the head from the pin to the back
// r_pin, r_back: the radiuses of the pin and the back sphere width: This
// is the full width from the pin center to the back center m: The object
// mesh.
// The return value is the hit result from the ray casting. If the starting
// point was inside the model, an "invalid" hit_result will be returned
// with a zero distance value instead of a NAN. This way the result can
// be used safely for comparison with other distances.
EigenMesh3D::hit_result pinhead_mesh_intersect(
const Vec3d& s,
const Vec3d& dir,
double r_pin,
double r_back,
double width)
{
static const size_t SAMPLES = 8;
// method based on:
// https://math.stackexchange.com/questions/73237/parametric-equation-of-a-circle-in-3d-space
// We will shoot multiple rays from the head pinpoint in the direction
// of the pinhead robe (side) surface. The result will be the smallest
// hit distance.
// Move away slightly from the touching point to avoid raycasting on the
// inner surface of the mesh.
Vec3d v = dir; // Our direction (axis)
Vec3d c = s + width * dir;
const double& sd = m_cfg.safety_distance_mm;
// Two vectors that will be perpendicular to each other and to the
// axis. Values for a(X) and a(Y) are now arbitrary, a(Z) is just a
// placeholder.
Vec3d a(0, 1, 0), b;
// The portions of the circle (the head-back circle) for which we will
// shoot rays.
std::array<double, SAMPLES> phis;
for(size_t i = 0; i < phis.size(); ++i) phis[i] = i*2*PI/phis.size();
auto& m = m_mesh;
using HitResult = EigenMesh3D::hit_result;
// Hit results
std::array<HitResult, SAMPLES> hits;
// We have to address the case when the direction vector v (same as
// dir) is coincident with one of the world axes. In this case two of
// its components will be completely zero and one is 1.0. Our method
// becomes dangerous here due to division with zero. Instead, vector
// 'a' can be an element-wise rotated version of 'v'
auto chk1 = [] (double val) {
return std::abs(std::abs(val) - 1) < 1e-20;
};
if(chk1(v(X)) || chk1(v(Y)) || chk1(v(Z))) {
a = {v(Z), v(X), v(Y)};
b = {v(Y), v(Z), v(X)};
}
else {
a(Z) = -(v(Y)*a(Y)) / v(Z); a.normalize();
b = a.cross(v);
}
// Now a and b vectors are perpendicular to v and to each other.
// Together they define the plane where we have to iterate with the
// given angles in the 'phis' vector
tbb::parallel_for(size_t(0), phis.size(),
[&phis, &hits, &m, sd, r_pin, r_back, s, a, b, c]
(size_t i)
{
double& phi = phis[i];
double sinphi = std::sin(phi);
double cosphi = std::cos(phi);
// Let's have a safety coefficient for the radiuses.
double rpscos = (sd + r_pin) * cosphi;
double rpssin = (sd + r_pin) * sinphi;
double rpbcos = (sd + r_back) * cosphi;
double rpbsin = (sd + r_back) * sinphi;
// Point on the circle on the pin sphere
Vec3d ps(s(X) + rpscos * a(X) + rpssin * b(X),
s(Y) + rpscos * a(Y) + rpssin * b(Y),
s(Z) + rpscos * a(Z) + rpssin * b(Z));
// Point ps is not on mesh but can be inside or outside as well.
// This would cause many problems with ray-casting. To detect the
// position we will use the ray-casting result (which has an
// is_inside predicate).
// This is the point on the circle on the back sphere
Vec3d p(c(X) + rpbcos * a(X) + rpbsin * b(X),
c(Y) + rpbcos * a(Y) + rpbsin * b(Y),
c(Z) + rpbcos * a(Z) + rpbsin * b(Z));
Vec3d n = (p - ps).normalized();
auto q = m.query_ray_hit(ps + sd*n, n);
if(q.is_inside()) { // the hit is inside the model
if(q.distance() > r_pin + sd) {
// If we are inside the model and the hit distance is bigger
// than our pin circle diameter, it probably indicates that
// the support point was already inside the model, or there
// is really no space around the point. We will assign a
// zero hit distance to these cases which will enforce the
// function return value to be an invalid ray with zero hit
// distance. (see min_element at the end)
hits[i] = HitResult(0.0);
}
else {
// re-cast the ray from the outside of the object.
// The starting point has an offset of 2*safety_distance
// because the original ray has also had an offset
auto q2 = m.query_ray_hit(ps + (q.distance() + 2*sd)*n, n);
hits[i] = q2;
}
} else hits[i] = q;
});
auto mit = std::min_element(hits.begin(), hits.end());
return *mit;
}
// Checking bridge (pillar and stick as well) intersection with the model.
// If the function is used for headless sticks, the ins_check parameter
// have to be true as the beginning of the stick might be inside the model
// geometry.
// The return value is the hit result from the ray casting. If the starting
// point was inside the model, an "invalid" hit_result will be returned
// with a zero distance value instead of a NAN. This way the result can
// be used safely for comparison with other distances.
EigenMesh3D::hit_result bridge_mesh_intersect(
const Vec3d& s,
const Vec3d& dir,
double r,
bool ins_check = false)
{
static const size_t SAMPLES = 8;
// helper vector calculations
Vec3d a(0, 1, 0), b;
const double& sd = m_cfg.safety_distance_mm;
// INFO: for explanation of the method used here, see the previous
// method's comments.
auto chk1 = [] (double val) {
return std::abs(std::abs(val) - 1) < 1e-20;
};
if(chk1(dir(X)) || chk1(dir(Y)) || chk1(dir(Z))) {
a = {dir(Z), dir(X), dir(Y)};
b = {dir(Y), dir(Z), dir(X)};
}
else {
a(Z) = -(dir(Y)*a(Y)) / dir(Z); a.normalize();
b = a.cross(dir);
}
// circle portions
std::array<double, SAMPLES> phis;
for(size_t i = 0; i < phis.size(); ++i) phis[i] = i*2*PI/phis.size();
auto& m = m_mesh;
using HitResult = EigenMesh3D::hit_result;
// Hit results
std::array<HitResult, SAMPLES> hits;
tbb::parallel_for(size_t(0), phis.size(),
[&m, &phis, a, b, sd, dir, r, s, ins_check, &hits]
(size_t i)
{
double& phi = phis[i];
double sinphi = std::sin(phi);
double cosphi = std::cos(phi);
// Let's have a safety coefficient for the radiuses.
double rcos = (sd + r) * cosphi;
double rsin = (sd + r) * sinphi;
// Point on the circle on the pin sphere
Vec3d p (s(X) + rcos * a(X) + rsin * b(X),
s(Y) + rcos * a(Y) + rsin * b(Y),
s(Z) + rcos * a(Z) + rsin * b(Z));
auto hr = m.query_ray_hit(p + sd*dir, dir);
if(ins_check && hr.is_inside()) {
if(hr.distance() > r + sd) hits[i] = HitResult(0.0);
else {
// re-cast the ray from the outside of the object
auto hr2 =
m.query_ray_hit(p + (hr.distance() + 2*sd)*dir, dir);
hits[i] = hr2;
}
} else hits[i] = hr;
});
auto mit = std::min_element(hits.begin(), hits.end());
return *mit;
}
// Helper function for interconnecting two pillars with zig-zag bridges.
bool interconnect(const Pillar& pillar, const Pillar& nextpillar)
{
// We need to get the starting point of the zig-zag pattern. We have to
// be aware that the two head junctions are at different heights. We
// may start from the lowest junction and call it a day but this
// strategy would leave unconnected a lot of pillar duos where the
// shorter pillar is too short to start a new bridge but the taller
// pillar could still be bridged with the shorter one.
bool was_connected = false;
Vec3d supper = pillar.startpoint();
Vec3d slower = nextpillar.startpoint();
Vec3d eupper = pillar.endpoint();
Vec3d elower = nextpillar.endpoint();
double zmin = m_result.ground_level + m_cfg.base_height_mm;
eupper(Z) = std::max(eupper(Z), zmin);
elower(Z) = std::max(elower(Z), zmin);
// The usable length of both pillars should be positive
if(slower(Z) - elower(Z) < 0) return false;
if(supper(Z) - eupper(Z) < 0) return false;
double pillar_dist = distance(Vec2d{slower(X), slower(Y)},
Vec2d{supper(X), supper(Y)});
double bridge_distance = pillar_dist / std::cos(-m_cfg.bridge_slope);
double zstep = pillar_dist * std::tan(-m_cfg.bridge_slope);
if(pillar_dist < 2 * m_cfg.head_back_radius_mm ||
pillar_dist > m_cfg.max_pillar_link_distance_mm) return false;
if(supper(Z) < slower(Z)) supper.swap(slower);
if(eupper(Z) < elower(Z)) eupper.swap(elower);
double startz = 0, endz = 0;
startz = slower(Z) - zstep < supper(Z) ? slower(Z) - zstep : slower(Z);
endz = eupper(Z) + zstep > elower(Z) ? eupper(Z) + zstep : eupper(Z);
if(slower(Z) - eupper(Z) < std::abs(zstep)) {
// no space for even one cross
// Get max available space
startz = std::min(supper(Z), slower(Z) - zstep);
endz = std::max(eupper(Z) + zstep, elower(Z));
// Align to center
double available_dist = (startz - endz);
double rounds = std::floor(available_dist / std::abs(zstep));
startz -= 0.5 * (available_dist - rounds * std::abs(zstep));;
}
auto pcm = m_cfg.pillar_connection_mode;
bool docrosses =
pcm == PillarConnectionMode::cross ||
(pcm == PillarConnectionMode::dynamic &&
pillar_dist > 2*m_cfg.base_radius_mm);
// 'sj' means starting junction, 'ej' is the end junction of a bridge.
// They will be swapped in every iteration thus the zig-zag pattern.
// According to a config parameter, a second bridge may be added which
// results in a cross connection between the pillars.
Vec3d sj = supper, ej = slower; sj(Z) = startz; ej(Z) = sj(Z) + zstep;
// TODO: This is a workaround to not have a faulty last bridge
while(ej(Z) >= eupper(Z) /*endz*/) {
if(bridge_mesh_intersect(sj,
dirv(sj, ej),
pillar.r) >= bridge_distance)
{
m_result.add_bridge(sj, ej, pillar.r);
was_connected = true;
}
// double bridging: (crosses)
if(docrosses) {
Vec3d sjback(ej(X), ej(Y), sj(Z));
Vec3d ejback(sj(X), sj(Y), ej(Z));
if(sjback(Z) <= slower(Z) && ejback(Z) >= eupper(Z) &&
bridge_mesh_intersect(sjback,
dirv(sjback, ejback),
pillar.r) >= bridge_distance)
{
// need to check collision for the cross stick
m_result.add_bridge(sjback, ejback, pillar.r);
was_connected = true;
}
}
sj.swap(ej);
ej(Z) = sj(Z) + zstep;
}
return was_connected;
}
// For connecting a head to a nearby pillar.
bool connect_to_nearpillar(const Head& head, long nearpillar_id) {
auto nearpillar = [this, nearpillar_id]() { return m_result.pillar(nearpillar_id); };
if(nearpillar().bridges > m_cfg.max_bridges_on_pillar) return false;
Vec3d headjp = head.junction_point();
Vec3d nearjp_u = nearpillar().startpoint();
Vec3d nearjp_l = nearpillar().endpoint();
double r = head.r_back_mm;
double d2d = distance(to_2d(headjp), to_2d(nearjp_u));
double d3d = distance(headjp, nearjp_u);
double hdiff = nearjp_u(Z) - headjp(Z);
double slope = std::atan2(hdiff, d2d);
Vec3d bridgestart = headjp;
Vec3d bridgeend = nearjp_u;
double max_len = m_cfg.max_bridge_length_mm;
double max_slope = m_cfg.bridge_slope;
double zdiff = 0.0;
// check the default situation if feasible for a bridge
if(d3d > max_len || slope > -max_slope) {
// not feasible to connect the two head junctions. We have to search
// for a suitable touch point.
double Zdown = headjp(Z) + d2d * std::tan(-max_slope);
Vec3d touchjp = bridgeend; touchjp(Z) = Zdown;
double D = distance(headjp, touchjp);
zdiff = Zdown - nearjp_u(Z);
if(zdiff > 0) {
Zdown -= zdiff;
bridgestart(Z) -= zdiff;
touchjp(Z) = Zdown;
double t = bridge_mesh_intersect(headjp, {0,0,-1}, r);
// We can't insert a pillar under the source head to connect
// with the nearby pillar's starting junction
if(t < zdiff) return false;
}
if(Zdown <= nearjp_u(Z) && Zdown >= nearjp_l(Z) && D < max_len)
bridgeend(Z) = Zdown;
else
return false;
}
// There will be a minimum distance from the ground where the
// bridge is allowed to connect. This is an empiric value.
double minz = m_result.ground_level + 2 * m_cfg.head_width_mm;
if(bridgeend(Z) < minz) return false;
double t = bridge_mesh_intersect(bridgestart,
dirv(bridgestart, bridgeend), r);
// Cannot insert the bridge. (further search might not worth the hassle)
if(t < distance(bridgestart, bridgeend)) return false;
// A partial pillar is needed under the starting head.
if(zdiff > 0) {
m_result.add_pillar(unsigned(head.id), bridgestart, r);
m_result.add_junction(bridgestart, r);
}
m_result.add_bridge(bridgestart, bridgeend, r);
m_result.increment_bridges(nearpillar());
return true;
}
bool search_pillar_and_connect(const Head& head) {
SpatIndex spindex = m_pillar_index;
long nearest_id = -1;
Vec3d querypoint = head.junction_point();
while(nearest_id < 0 && !spindex.empty()) { m_thr();
// loop until a suitable head is not found
// if there is a pillar closer than the cluster center
// (this may happen as the clustering is not perfect)
// than we will bridge to this closer pillar
Vec3d qp(querypoint(X), querypoint(Y), m_result.ground_level);
auto qres = spindex.nearest(qp, 1);
if(qres.empty()) break;
auto ne = qres.front();
nearest_id = ne.second;
if(nearest_id >= 0) {
auto nearpillarID = unsigned(nearest_id);
if(nearpillarID < m_result.pillars().size()) {
if(!connect_to_nearpillar(head, nearpillarID)) {
nearest_id = -1; // continue searching
spindex.remove(ne); // without the current pillar
}
}
}
}
return nearest_id >= 0;
}
public:
Algorithm(const SupportConfig& config,
const EigenMesh3D& emesh,
const std::vector<SupportPoint>& support_pts,
Result& result,
ThrowOnCancel thr) :
m_cfg(config),
m_mesh(emesh),
m_support_pts(support_pts),
m_support_nmls(support_pts.size(), 3),
m_result(result),
m_points(support_pts.size(), 3),
m_thr(thr)
{
// Prepare the support points in Eigen/IGL format as well, we will use
// it mostly in this form.
long i = 0;
for(const SupportPoint& sp : m_support_pts) {
m_points.row(i)(X) = double(sp.pos(X));
m_points.row(i)(Y) = double(sp.pos(Y));
m_points.row(i)(Z) = double(sp.pos(Z));
++i;
}
}
// Now let's define the individual steps of the support generation algorithm
// Filtering step: here we will discard inappropriate support points
// and decide the future of the appropriate ones. We will check if a
// pinhead is applicable and adjust its angle at each support point. We
// will also merge the support points that are just too close and can
// be considered as one.
void filter() {
// Get the points that are too close to each other and keep only the
// first one
auto aliases = cluster(m_points, D_SP, 2);
PtIndices filtered_indices;
filtered_indices.reserve(aliases.size());
m_iheads.reserve(aliases.size());
m_iheadless.reserve(aliases.size());
for(auto& a : aliases) {
// Here we keep only the front point of the cluster.
filtered_indices.emplace_back(a.front());
}
// calculate the normals to the triangles for filtered points
auto nmls = sla::normals(m_points, m_mesh, m_cfg.head_front_radius_mm,
m_thr, filtered_indices);
// Not all of the support points have to be a valid position for
// support creation. The angle may be inappropriate or there may
// not be enough space for the pinhead. Filtering is applied for
// these reasons.
using libnest2d::opt::bound;
using libnest2d::opt::initvals;
using libnest2d::opt::GeneticOptimizer;
using libnest2d::opt::StopCriteria;
for(unsigned i = 0, fidx = 0; i < filtered_indices.size(); ++i)
{
m_thr();
fidx = filtered_indices[i];
auto n = nmls.row(i);
// for all normals we generate the spherical coordinates and
// saturate the polar angle to 45 degrees from the bottom then
// convert back to standard coordinates to get the new normal.
// Then we just create a quaternion from the two normals
// (Quaternion::FromTwoVectors) and apply the rotation to the
// arrow head.
double z = n(2);
double r = 1.0; // for normalized vector
double polar = std::acos(z / r);
double azimuth = std::atan2(n(1), n(0));
// skip if the tilt is not sane
if(polar >= PI - m_cfg.normal_cutoff_angle) {
// We saturate the polar angle to 3pi/4
polar = std::max(polar, 3*PI / 4);
// save the head (pinpoint) position
Vec3d hp = m_points.row(fidx);
double w = m_cfg.head_width_mm +
m_cfg.head_back_radius_mm +
2*m_cfg.head_front_radius_mm;
double pin_r = double(m_support_pts[fidx].head_front_radius);
// Reassemble the now corrected normal
auto nn = Vec3d(std::cos(azimuth) * std::sin(polar),
std::sin(azimuth) * std::sin(polar),
std::cos(polar)).normalized();
// check available distance
double t = pinhead_mesh_intersect(
hp, // touching point
nn, // normal
pin_r,
m_cfg.head_back_radius_mm,
w);
if(t <= w) {
// Let's try to optimize this angle, there might be a
// viable normal that doesn't collide with the model
// geometry and its very close to the default.
StopCriteria stc;
stc.max_iterations = m_cfg.optimizer_max_iterations;
stc.relative_score_difference = m_cfg.optimizer_rel_score_diff;
stc.stop_score = w; // space greater than w is enough
GeneticOptimizer solver(stc);
solver.seed(0); // we want deterministic behavior
auto oresult = solver.optimize_max(
[this, pin_r, w, hp](double plr, double azm)
{
auto n = Vec3d(std::cos(azm) * std::sin(plr),
std::sin(azm) * std::sin(plr),
std::cos(plr)).normalized();
double score = pinhead_mesh_intersect( hp, n, pin_r,
m_cfg.head_back_radius_mm, w);
return score;
},
initvals(polar, azimuth), // start with what we have
bound(3*PI/4, PI), // Must not exceed the tilt limit
bound(-PI, PI) // azimuth can be a full search
);
if(oresult.score > w) {
polar = std::get<0>(oresult.optimum);
azimuth = std::get<1>(oresult.optimum);
nn = Vec3d(std::cos(azimuth) * std::sin(polar),
std::sin(azimuth) * std::sin(polar),
std::cos(polar)).normalized();
t = oresult.score;
}
}
// save the verified and corrected normal
m_support_nmls.row(fidx) = nn;
if(t > w) {
// mark the point for needing a head.
m_iheads.emplace_back(fidx);
} else if( polar >= 3*PI/4 ) {
// Headless supports do not tilt like the headed ones so
// the normal should point almost to the ground.
m_iheadless.emplace_back(fidx);
}
}
}
m_thr();
}
// Pinhead creation: based on the filtering results, the Head objects
// will be constructed (together with their triangle meshes).
void add_pinheads()
{
for (unsigned i : m_iheads) {
m_thr();
m_result.add_head(
i,
m_cfg.head_back_radius_mm,
m_support_pts[i].head_front_radius,
m_cfg.head_width_mm,
m_cfg.head_penetration_mm,
m_support_nmls.row(i), // dir
m_support_pts[i].pos.cast<double>() // displacement
);
}
}
// Further classification of the support points with pinheads. If the
// ground is directly reachable through a vertical line parallel to the
// Z axis we consider a support point as pillar candidate. If touches
// the model geometry, it will be marked as non-ground facing and
// further steps will process it. Also, the pillars will be grouped
// into clusters that can be interconnected with bridges. Elements of
// these groups may or may not be interconnected. Here we only run the
// clustering algorithm.
void classify()
{
// We should first get the heads that reach the ground directly
PtIndices ground_head_indices;
ground_head_indices.reserve(m_iheads.size());
m_iheads_onmodel.reserve(m_iheads.size());
// First we decide which heads reach the ground and can be full
// pillars and which shall be connected to the model surface (or
// search a suitable path around the surface that leads to the
// ground -- TODO)
for(unsigned i : m_iheads) {
m_thr();
auto& head = m_result.head(i);
Vec3d n(0, 0, -1);
double r = head.r_back_mm;
Vec3d headjp = head.junction_point();
// collision check
auto hit = bridge_mesh_intersect(headjp, n, r);
if(std::isinf(hit.distance())) ground_head_indices.emplace_back(i);
else if(m_cfg.ground_facing_only) head.invalidate();
else m_iheads_onmodel.emplace_back(std::make_pair(i, hit));
}
// We want to search for clusters of points that are far enough
// from each other in the XY plane to not cross their pillar bases
// These clusters of support points will join in one pillar,
// possibly in their centroid support point.
auto pointfn = [this](unsigned i) {
return m_result.head(i).junction_point();
};
auto predicate = [this](const SpatElement& e1, const SpatElement& e2) {
double d2d = distance(to_2d(e1.first), to_2d(e2.first));
double d3d = distance(e1.first, e2.first);
return d2d < 2 * m_cfg.base_radius_mm &&
d3d < m_cfg.max_bridge_length_mm;
};
m_pillar_clusters = cluster(ground_head_indices, pointfn, predicate,
m_cfg.max_bridges_on_pillar);
}
// Step: Routing the ground connected pinheads, and interconnecting
// them with additional (angled) bridges. Not all of these pinheads
// will be a full pillar (ground connected). Some will connect to a
// nearby pillar using a bridge. The max number of such side-heads for
// a central pillar is limited to avoid bad weight distribution.
void routing_to_ground()
{
const double pradius = m_cfg.head_back_radius_mm;
const double gndlvl = m_result.ground_level;
ClusterEl cl_centroids;
cl_centroids.reserve(m_pillar_clusters.size());
for(auto& cl : m_pillar_clusters) { m_thr();
// place all the centroid head positions into the index. We
// will query for alternative pillar positions. If a sidehead
// cannot connect to the cluster centroid, we have to search
// for another head with a full pillar. Also when there are two
// elements in the cluster, the centroid is arbitrary and the
// sidehead is allowed to connect to a nearby pillar to
// increase structural stability.
if(cl.empty()) continue;
// get the current cluster centroid
auto& thr = m_thr; const auto& points = m_points;
long lcid = cluster_centroid(cl,
[&points](size_t idx) { return points.row(long(idx)); },
[thr](const Vec3d& p1, const Vec3d& p2)
{
thr();
return distance(Vec2d(p1(X), p1(Y)), Vec2d(p2(X), p2(Y)));
});
assert(lcid >= 0);
unsigned hid = cl[size_t(lcid)]; // Head ID
cl_centroids.emplace_back(hid);
Head& h = m_result.head(hid);
h.transform();
Vec3d p = h.junction_point(); p(Z) = gndlvl;
auto& plr = m_result.add_pillar(hid, p, h.r_back_mm)
.add_base(m_cfg.base_height_mm,
m_cfg.base_radius_mm);
// Save the pillar endpoint and the pillar id in the spatial index
m_pillar_index.insert(plr.endpoint(), unsigned(plr.id));
}
// now we will go through the clusters ones again and connect the
// sidepoints with the cluster centroid (which is a ground pillar)
// or a nearby pillar if the centroid is unreachable.
size_t ci = 0;
for(auto cl : m_pillar_clusters) { m_thr();
auto cidx = cl_centroids[ci++];
// TODO: don't consider the cluster centroid but calculate a
// central position where the pillar can be placed. this way
// the weight is distributed more effectively on the pillar.
auto centerpillarID = m_result.head_pillar(cidx).id;
for(auto c : cl) { m_thr();
if(c == cidx) continue;
auto& sidehead = m_result.head(c);
sidehead.transform();
if(!connect_to_nearpillar(sidehead, centerpillarID) &&
!search_pillar_and_connect(sidehead))
{
Vec3d pstart = sidehead.junction_point();
Vec3d pend = Vec3d{pstart(X), pstart(Y), gndlvl};
// Could not find a pillar, create one
auto& pillar = m_result.add_pillar(unsigned(sidehead.id),
pend, pradius)
.add_base(m_cfg.base_height_mm,
m_cfg.base_radius_mm);
// connects to ground, eligible for bridging
m_pillar_index.insert(pend, unsigned(pillar.id));
}
}
}
}
// Step: routing the pinheads that would connect to the model surface
// along the Z axis downwards. For now these will actually be connected with
// the model surface with a flipped pinhead. In the future here we could use
// some smart algorithms to search for a safe path to the ground or to a
// nearby pillar that can hold the supported weight.
void routing_to_model()
{
// We need to check if there is an easy way out to the bed surface.
// If it can be routed there with a bridge shorter than
// min_bridge_distance.
// First we want to index the available pillars. The best is to connect
// these points to the available pillars
auto routedown = [this](Head& head, const Vec3d& dir, double dist)
{
head.transform();
Vec3d hjp = head.junction_point();
Vec3d endp = hjp + dist * dir;
m_result.add_bridge(hjp, endp, head.r_back_mm);
m_result.add_junction(endp, head.r_back_mm);
auto groundp = endp;
groundp(Z) = m_result.ground_level;
auto& newpillar = m_result.add_pillar(endp, groundp, head.r_back_mm)
.add_base(m_cfg.base_height_mm,
m_cfg.base_radius_mm);
m_pillar_index.insert(groundp, unsigned(newpillar.id));
};
std::vector<unsigned> modelpillars;
// TODO: connect these to the ground pillars if possible
for(auto item : m_iheads_onmodel) { m_thr();
unsigned idx = item.first;
EigenMesh3D::hit_result hit = item.second;
auto& head = m_result.head(idx);
Vec3d hjp = head.junction_point();
// /////////////////////////////////////////////////////////////////
// Search nearby pillar
// /////////////////////////////////////////////////////////////////
if(search_pillar_and_connect(head)) { head.transform(); continue; }
// /////////////////////////////////////////////////////////////////
// Try straight path
// /////////////////////////////////////////////////////////////////
// Cannot connect to nearby pillar. We will try to search for
// a route to the ground.
double t = bridge_mesh_intersect(hjp, head.dir, head.r_back_mm);
double d = 0, tdown = 0;
Vec3d dirdown(0.0, 0.0, -1.0);
t = std::min(t, m_cfg.max_bridge_length_mm);
while(d < t && !std::isinf(tdown = bridge_mesh_intersect(
hjp + d*head.dir,
dirdown, head.r_back_mm))) {
d += head.r_back_mm;
}
if(std::isinf(tdown)) { // we heave found a route to the ground
routedown(head, head.dir, d); continue;
}
// /////////////////////////////////////////////////////////////////
// Optimize bridge direction
// /////////////////////////////////////////////////////////////////
// Straight path failed so we will try to search for a suitable
// direction out of the cavity.
// Get the spherical representation of the normal. its easier to
// work with.
double z = head.dir(Z);
double r = 1.0; // for normalized vector
double polar = std::acos(z / r);
double azimuth = std::atan2(head.dir(Y), head.dir(X));
using libnest2d::opt::bound;
using libnest2d::opt::initvals;
using libnest2d::opt::GeneticOptimizer;
using libnest2d::opt::StopCriteria;
StopCriteria stc;
stc.max_iterations = m_cfg.optimizer_max_iterations;
stc.relative_score_difference = m_cfg.optimizer_rel_score_diff;
stc.stop_score = 1e6;
GeneticOptimizer solver(stc);
solver.seed(0); // we want deterministic behavior
double r_back = head.r_back_mm;
auto oresult = solver.optimize_max(
[this, hjp, r_back](double plr, double azm)
{
Vec3d n = Vec3d(std::cos(azm) * std::sin(plr),
std::sin(azm) * std::sin(plr),
std::cos(plr)).normalized();
return bridge_mesh_intersect(hjp, n, r_back);
},
initvals(polar, azimuth), // let's start with what we have
bound(3*PI/4, PI), // Must not exceed the slope limit
bound(-PI, PI) // azimuth can be a full range search
);
d = 0; t = oresult.score;
polar = std::get<0>(oresult.optimum);
azimuth = std::get<1>(oresult.optimum);
Vec3d bridgedir = Vec3d(std::cos(azimuth) * std::sin(polar),
std::sin(azimuth) * std::sin(polar),
std::cos(polar)).normalized();
t = std::min(t, m_cfg.max_bridge_length_mm);
while(d < t && !std::isinf(tdown = bridge_mesh_intersect(
hjp + d*bridgedir,
dirdown,
head.r_back_mm))) {
d += head.r_back_mm;
}
if(std::isinf(tdown)) { // we heave found a route to the ground
routedown(head, bridgedir, d); continue;
}
// /////////////////////////////////////////////////////////////////
// Route to model body
// /////////////////////////////////////////////////////////////////
double zangle = std::asin(hit.direction()(Z));
zangle = std::max(zangle, PI/4);
double h = std::sin(zangle) * head.fullwidth();
// The width of the tail head that we would like to have...
h = std::min(hit.distance() - head.r_back_mm, h);
if(h > 0) {
Vec3d endp{hjp(X), hjp(Y), hjp(Z) - hit.distance() + h};
auto center_hit = m_mesh.query_ray_hit(hjp, dirdown);
double hitdiff = center_hit.distance() - hit.distance();
Vec3d hitp = std::abs(hitdiff) < 2*head.r_back_mm?
center_hit.position() : hit.position();
head.transform();
Pillar& pill = m_result.add_pillar(unsigned(head.id),
endp,
head.r_back_mm);
Vec3d taildir = endp - hitp;
double dist = distance(endp, hitp) + m_cfg.head_penetration_mm;
double w = dist - 2 * head.r_pin_mm - head.r_back_mm;
Head tailhead(head.r_back_mm,
head.r_pin_mm,
w,
m_cfg.head_penetration_mm,
taildir,
hitp);
tailhead.transform();
pill.base = tailhead.mesh;
// Experimental: add the pillar to the index for cascading
modelpillars.emplace_back(unsigned(pill.id));
continue;
}
// We have failed to route this head.
BOOST_LOG_TRIVIAL(warning)
<< "Failed to route model facing support point."
<< " ID: " << idx;
head.invalidate();
}
for(auto pillid : modelpillars) {
auto& pillar = m_result.pillar(pillid);
m_pillar_index.insert(pillar.endpoint(), pillid);
}
}
void interconnect_pillars() {
// Now comes the algorithm that connects pillars with each other.
// Ideally every pillar should be connected with at least one of its
// neighbors if that neighbor is within max_pillar_link_distance
// Pillars with height exceeding H1 will require at least one neighbor
// to connect with. Height exceeding H2 require two neighbors.
double H1 = m_cfg.max_solo_pillar_height_mm;
double H2 = m_cfg.max_dual_pillar_height_mm;
double d = m_cfg.max_pillar_link_distance_mm;
//A connection between two pillars only counts if the height ratio is
// bigger than 50%
double min_height_ratio = 0.5;
std::set<unsigned long> pairs;
auto cascadefn =
[this, d, &pairs, min_height_ratio, H1] (const SpatElement& el)
{
Vec3d qp = el.first;
const Pillar& pillar = m_result.pillar(el.second);
unsigned neighbors = m_cfg.pillar_cascade_neighbors;
// connections are enough for one pillar
if(pillar.links >= neighbors) return;
// Query all remaining points within reach
auto qres = m_pillar_index.query([qp, d](const SpatElement& e){
return distance(e.first, qp) < d;
});
// sort the result by distance (have to check if this is needed)
std::sort(qres.begin(), qres.end(),
[qp](const SpatElement& e1, const SpatElement& e2){
return distance(e1.first, qp) < distance(e2.first, qp);
});
for(auto& re : qres) {
if(re.second == el.second) continue;
auto a = el.second, b = re.second;
// I hope that the area of a square is never equal to its
// circumference
auto hashval = 2 * (a + b) + a * b;
if(pairs.find(hashval) != pairs.end()) continue;
const Pillar& neighborpillar = m_result.pillars()[re.second];
// this neighbor is occupied
if(neighborpillar.links >= neighbors) continue;
if(interconnect(pillar, neighborpillar)) {
pairs.insert(hashval);
// If the interconnection length between the two pillars is
// less than 50% of the longer pillar's height, don't count
if(pillar.height < H1 ||
neighborpillar.height / pillar.height > min_height_ratio)
m_result.increment_links(pillar);
if(neighborpillar.height < H1 ||
pillar.height / neighborpillar.height > min_height_ratio)
m_result.increment_links(neighborpillar);
}
// connections are enough for one pillar
if(pillar.links >= neighbors) break;
}
};
m_pillar_index.foreach(cascadefn);
size_t pillarcount = m_result.pillars().size();
for(size_t pid = 0; pid < pillarcount; pid++) {
auto pillar = [this, pid]() { return m_result.pillar(pid); };
unsigned needpillars = 0;
if(pillar().bridges > m_cfg.max_bridges_on_pillar) needpillars = 3;
else if(pillar().links < 2 && pillar().height > H2) {
// Not enough neighbors to support this pillar
needpillars = 2 - pillar().links;
}
else if(pillar().links < 1 && pillar().height > H1) {
// No neighbors could be found and the pillar is too long.
needpillars = 1;
}
// Search for new pillar locations
bool found = false;
double alpha = 0; // goes to 2Pi
double r = 2 * m_cfg.base_radius_mm;
Vec3d pillarsp = pillar().startpoint();
Vec3d sp(pillarsp(X), pillarsp(Y), pillarsp(Z) - r);
std::vector<bool> tv(needpillars, false);
std::vector<Vec3d> spts(needpillars);
while(!found && alpha < 2*PI) {
for(unsigned n = 0; n < needpillars; n++) {
double a = alpha + n * PI/3;
Vec3d s = sp;
s(X) += std::cos(a) * r;
s(Y) += std::sin(a) * r;
spts[n] = s;
auto hr = bridge_mesh_intersect(s, {0, 0, -1}, pillar().r);
tv[n] = std::isinf(hr.distance());
}
found = std::all_of(tv.begin(), tv.end(), [](bool v){return v;});
// 20 angles will be tried...
alpha += 0.1 * PI;
}
std::vector<long> newpills;
newpills.reserve(needpillars);
if(found) for(unsigned n = 0; n < needpillars; n++) {
Vec3d s = spts[n]; double gnd = m_result.ground_level;
Pillar p(s, Vec3d(s(X), s(Y), gnd), pillar().r);
p.add_base(m_cfg.base_height_mm, m_cfg.base_radius_mm);
if(interconnect(pillar(), p)) {
Pillar& pp = m_result.add_pillar(p);
m_pillar_index.insert(pp.endpoint(), unsigned(pp.id));
m_result.add_junction(s, pillar().r);
double t = bridge_mesh_intersect(pillarsp,
dirv(pillarsp, s),
pillar().r);
if(distance(pillarsp, s) < t)
m_result.add_bridge(pillarsp, s, pillar().r);
if(pillar().endpoint()(Z) > m_result.ground_level)
m_result.add_junction(pillar().endpoint(), pillar().r);
newpills.emplace_back(pp.id);
m_result.increment_links(pillar());
}
}
if(!newpills.empty()) {
for(auto it = newpills.begin(), nx = std::next(it);
nx != newpills.end(); ++it, ++nx) {
const Pillar& itpll = m_result.pillar(*it);
const Pillar& nxpll = m_result.pillar(*nx);
if(interconnect(itpll, nxpll)) {
m_result.increment_links(itpll);
m_result.increment_links(nxpll);
}
}
m_pillar_index.foreach(cascadefn);
}
}
}
// Step: process the support points where there is not enough space for a
// full pinhead. In this case we will use a rounded sphere as a touching
// point and use a thinner bridge (let's call it a stick).
void routing_headless ()
{
// For now we will just generate smaller headless sticks with a sharp
// ending point that connects to the mesh surface.
// We will sink the pins into the model surface for a distance of 1/3 of
// the pin radius
for(unsigned i : m_iheadless) { m_thr();
const auto R = double(m_support_pts[i].head_front_radius);
const double HWIDTH_MM = R/3;
// Exact support position
Vec3d sph = m_support_pts[i].pos.cast<double>();
Vec3d n = m_support_nmls.row(i); // mesh outward normal
Vec3d sp = sph - n * HWIDTH_MM; // stick head start point
Vec3d dir = {0, 0, -1};
Vec3d sj = sp + R * n; // stick start point
// This is only for checking
double idist = bridge_mesh_intersect(sph, dir, R, true);
double dist = ray_mesh_intersect(sj, dir);
if(std::isinf(idist) || std::isnan(idist) || idist < 2*R ||
std::isinf(dist) || std::isnan(dist) || dist < 2*R) {
BOOST_LOG_TRIVIAL(warning) << "Can not find route for headless"
<< " support stick at: "
<< sj.transpose();
continue;
}
Vec3d ej = sj + (dist + HWIDTH_MM)* dir;
m_result.add_compact_bridge(sp, ej, n, R);
}
}
};
bool SLASupportTree::generate(const std::vector<SupportPoint> &support_points,
const EigenMesh3D& mesh,
const SupportConfig &cfg,
const Controller &ctl)
{
if(support_points.empty()) return false;
Algorithm alg(cfg, mesh, support_points, *m_impl, ctl.cancelfn);
// Let's define the individual steps of the processing. We can experiment
// later with the ordering and the dependencies between them.
enum Steps {
BEGIN,
FILTER,
PINHEADS,
CLASSIFY,
ROUTING_GROUND,
ROUTING_NONGROUND,
CASCADE_PILLARS,
HEADLESS,
DONE,
ABORT,
NUM_STEPS
//...
};
// Collect the algorithm steps into a nice sequence
std::array<std::function<void()>, NUM_STEPS> program = {
[] () {
// Begin...
// Potentially clear up the shared data (not needed for now)
},
std::bind(&Algorithm::filter, &alg),
std::bind(&Algorithm::add_pinheads, &alg),
std::bind(&Algorithm::classify, &alg),
std::bind(&Algorithm::routing_to_ground, &alg),
std::bind(&Algorithm::routing_to_model, &alg),
std::bind(&Algorithm::interconnect_pillars, &alg),
std::bind(&Algorithm::routing_headless, &alg),
[] () {
// Done
},
[] () {
// Abort
}
};
Steps pc = BEGIN;
if(cfg.ground_facing_only) {
program[ROUTING_NONGROUND] = []() {
BOOST_LOG_TRIVIAL(info)
<< "Skipping model-facing supports as requested.";
};
program[HEADLESS] = []() {
BOOST_LOG_TRIVIAL(info) << "Skipping headless stick generation as"
" requested.";
};
}
// Let's define a simple automaton that will run our program.
auto progress = [&ctl, &pc] () {
static const std::array<std::string, NUM_STEPS> stepstr {
"Starting",
"Filtering",
"Generate pinheads",
"Classification",
"Routing to ground",
"Routing supports to model surface",
"Interconnecting pillars",
"Processing small holes",
"Done",
"Abort"
};
static const std::array<unsigned, NUM_STEPS> stepstate {
0,
10,
30,
50,
60,
70,
80,
90,
100,
0
};
if(ctl.stopcondition()) pc = ABORT;
switch(pc) {
case BEGIN: pc = FILTER; break;
case FILTER: pc = PINHEADS; break;
case PINHEADS: pc = CLASSIFY; break;
case CLASSIFY: pc = ROUTING_GROUND; break;
case ROUTING_GROUND: pc = ROUTING_NONGROUND; break;
case ROUTING_NONGROUND: pc = CASCADE_PILLARS; break;
case CASCADE_PILLARS: pc = HEADLESS; break;
case HEADLESS: pc = DONE; break;
case DONE:
case ABORT: break;
default: ;
}
ctl.statuscb(stepstate[pc], stepstr[pc]);
};
// Just here we run the computation...
while(pc < DONE) {
progress();
program[pc]();
}
return pc == ABORT;
}
SLASupportTree::SLASupportTree(): m_impl(new Impl()) {}
const TriangleMesh &SLASupportTree::merged_mesh() const
{
return get().merged_mesh();
}
void SLASupportTree::merged_mesh_with_pad(TriangleMesh &outmesh) const {
outmesh.merge(merged_mesh());
outmesh.merge(get_pad());
}
SlicedSupports SLASupportTree::slice(float layerh, float init_layerh) const
{
if(init_layerh < 0) init_layerh = layerh;
auto& stree = get();
const auto modelh = float(stree.full_height());
auto gndlvl = float(this->m_impl->ground_level);
const Pad& pad = m_impl->pad();
if(!pad.empty()) gndlvl -= float(get_pad_elevation(pad.cfg));
std::vector<float> heights;
heights.reserve(size_t(modelh/layerh) + 1);
for(float h = gndlvl + init_layerh; h < gndlvl + modelh; h += layerh) {
heights.emplace_back(h);
}
TriangleMesh fullmesh = m_impl->merged_mesh();
fullmesh.merge(get_pad());
TriangleMeshSlicer slicer(&fullmesh);
SlicedSupports ret;
slicer.slice(heights, 0.f, &ret, get().ctl().cancelfn);
return ret;
}
SlicedSupports SLASupportTree::slice(const std::vector<float> &heights,
float cr) const
{
TriangleMesh fullmesh = m_impl->merged_mesh();
fullmesh.merge(get_pad());
TriangleMeshSlicer slicer(&fullmesh);
SlicedSupports ret;
slicer.slice(heights, cr, &ret, get().ctl().cancelfn);
return ret;
}
const TriangleMesh &SLASupportTree::add_pad(const SliceLayer& baseplate,
const PoolConfig& pcfg) const
{
// PoolConfig pcfg;
// pcfg.min_wall_thickness_mm = min_wall_thickness_mm;
// pcfg.min_wall_height_mm = min_wall_height_mm;
// pcfg.max_merge_distance_mm = max_merge_distance_mm;
// pcfg.edge_radius_mm = edge_radius_mm;
return m_impl->create_pad(merged_mesh(), baseplate, pcfg).tmesh;
}
const TriangleMesh &SLASupportTree::get_pad() const
{
return m_impl->pad().tmesh;
}
void SLASupportTree::remove_pad()
{
m_impl->remove_pad();
}
SLASupportTree::SLASupportTree(const std::vector<SupportPoint> &points,
const EigenMesh3D& emesh,
const SupportConfig &cfg,
const Controller &ctl):
m_impl(new Impl(ctl))
{
m_impl->ground_level = emesh.ground_level() - cfg.object_elevation_mm;
generate(points, emesh, cfg, ctl);
}
SLASupportTree::SLASupportTree(const SLASupportTree &c):
m_impl(new Impl(*c.m_impl)) {}
SLASupportTree &SLASupportTree::operator=(const SLASupportTree &c)
{
m_impl = make_unique<Impl>(*c.m_impl);
return *this;
}
SLASupportTree::~SLASupportTree() {}
}
}