271 lines
9.1 KiB
C++
271 lines
9.1 KiB
C++
#include "SupportTreeMesher.hpp"
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namespace Slic3r { namespace sla {
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indexed_triangle_set sphere(double rho, Portion portion, double fa) {
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indexed_triangle_set ret;
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// prohibit close to zero radius
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if(rho <= 1e-6 && rho >= -1e-6) return ret;
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auto& vertices = ret.vertices;
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auto& facets = ret.indices;
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// Algorithm:
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// Add points one-by-one to the sphere grid and form facets using relative
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// coordinates. Sphere is composed effectively of a mesh of stacked circles.
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// adjust via rounding to get an even multiple for any provided angle.
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double angle = (2 * PI / floor(2*PI / fa) );
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// Ring to be scaled to generate the steps of the sphere
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std::vector<double> ring;
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for (double i = 0; i < 2*PI; i+=angle) ring.emplace_back(i);
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const auto sbegin = size_t(2*std::get<0>(portion)/angle);
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const auto send = size_t(2*std::get<1>(portion)/angle);
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const size_t steps = ring.size();
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const double increment = 1.0 / double(steps);
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// special case: first ring connects to 0,0,0
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// insert and form facets.
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if (sbegin == 0)
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vertices.emplace_back(
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Vec3f(0.f, 0.f, float(-rho + increment * sbegin * 2. * rho)));
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auto id = coord_t(vertices.size());
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for (size_t i = 0; i < ring.size(); i++) {
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// Fixed scaling
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const double z = -rho + increment*rho*2.0 * (sbegin + 1.0);
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// radius of the circle for this step.
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const double r = std::sqrt(std::abs(rho*rho - z*z));
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Vec2d b = Eigen::Rotation2Dd(ring[i]) * Eigen::Vector2d(0, r);
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vertices.emplace_back(Vec3d(b(0), b(1), z).cast<float>());
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if (sbegin == 0)
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(i == 0) ? facets.emplace_back(coord_t(ring.size()), 0, 1) :
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facets.emplace_back(id - 1, 0, id);
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++id;
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}
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// General case: insert and form facets for each step,
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// joining it to the ring below it.
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for (size_t s = sbegin + 2; s < send - 1; s++) {
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const double z = -rho + increment * double(s * 2. * rho);
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const double r = std::sqrt(std::abs(rho*rho - z*z));
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for (size_t i = 0; i < ring.size(); i++) {
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Vec2d b = Eigen::Rotation2Dd(ring[i]) * Eigen::Vector2d(0, r);
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vertices.emplace_back(Vec3d(b(0), b(1), z).cast<float>());
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auto id_ringsize = coord_t(id - int(ring.size()));
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if (i == 0) {
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// wrap around
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facets.emplace_back(id - 1, id, id + coord_t(ring.size() - 1) );
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facets.emplace_back(id - 1, id_ringsize, id);
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} else {
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facets.emplace_back(id_ringsize - 1, id_ringsize, id);
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facets.emplace_back(id - 1, id_ringsize - 1, id);
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}
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id++;
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}
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}
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// special case: last ring connects to 0,0,rho*2.0
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// only form facets.
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if(send >= size_t(2*PI / angle)) {
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vertices.emplace_back(0.f, 0.f, float(-rho + increment*send*2.0*rho));
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for (size_t i = 0; i < ring.size(); i++) {
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auto id_ringsize = coord_t(id - int(ring.size()));
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if (i == 0) {
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// third vertex is on the other side of the ring.
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facets.emplace_back(id - 1, id_ringsize, id);
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} else {
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auto ci = coord_t(id_ringsize + coord_t(i));
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facets.emplace_back(ci - 1, ci, id);
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}
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}
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}
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id++;
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return ret;
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}
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indexed_triangle_set cylinder(double r, double h, size_t ssteps, const Vec3d &sp)
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{
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assert(ssteps > 0);
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indexed_triangle_set ret;
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auto steps = int(ssteps);
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auto& points = ret.vertices;
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auto& indices = ret.indices;
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points.reserve(2*ssteps);
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double a = 2*PI/steps;
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Vec3d jp = sp;
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Vec3d endp = {sp(X), sp(Y), sp(Z) + h};
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// Upper circle points
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for(int i = 0; i < steps; ++i) {
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double phi = i*a;
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auto ex = float(endp(X) + r*std::cos(phi));
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auto ey = float(endp(Y) + r*std::sin(phi));
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points.emplace_back(ex, ey, float(endp(Z)));
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}
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// Lower circle points
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for(int i = 0; i < steps; ++i) {
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double phi = i*a;
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auto x = float(jp(X) + r*std::cos(phi));
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auto y = float(jp(Y) + r*std::sin(phi));
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points.emplace_back(x, y, float(jp(Z)));
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}
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// Now create long triangles connecting upper and lower circles
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indices.reserve(2*ssteps);
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auto offs = steps;
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for(int i = 0; i < steps - 1; ++i) {
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indices.emplace_back(i, i + offs, offs + i + 1);
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indices.emplace_back(i, offs + i + 1, i + 1);
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}
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// Last triangle connecting the first and last vertices
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auto last = steps - 1;
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indices.emplace_back(0, last, offs);
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indices.emplace_back(last, offs + last, offs);
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// According to the slicing algorithms, we need to aid them with generating
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// a watertight body. So we create a triangle fan for the upper and lower
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// ending of the cylinder to close the geometry.
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points.emplace_back(jp.cast<float>()); int ci = int(points.size() - 1);
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for(int i = 0; i < steps - 1; ++i)
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indices.emplace_back(i + offs + 1, i + offs, ci);
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indices.emplace_back(offs, steps + offs - 1, ci);
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points.emplace_back(endp.cast<float>()); ci = int(points.size() - 1);
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for(int i = 0; i < steps - 1; ++i)
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indices.emplace_back(ci, i, i + 1);
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indices.emplace_back(steps - 1, 0, ci);
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return ret;
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}
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indexed_triangle_set pinhead(double r_pin,
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double r_back,
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double length,
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size_t steps)
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{
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assert(steps > 0);
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assert(length >= 0.);
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assert(r_back > 0.);
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assert(r_pin > 0.);
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indexed_triangle_set mesh;
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// We create two spheres which will be connected with a robe that fits
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// both circles perfectly.
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// Set up the model detail level
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const double detail = 2 * PI / steps;
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// We don't generate whole circles. Instead, we generate only the
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// portions which are visible (not covered by the robe) To know the
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// exact portion of the bottom and top circles we need to use some
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// rules of tangent circles from which we can derive (using simple
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// triangles the following relations:
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// The height of the whole mesh
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const double h = r_back + r_pin + length;
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double phi = PI / 2. - std::acos((r_back - r_pin) / h);
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// To generate a whole circle we would pass a portion of (0, Pi)
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// To generate only a half horizontal circle we can pass (0, Pi/2)
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// The calculated phi is an offset to the half circles needed to smooth
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// the transition from the circle to the robe geometry
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auto &&s1 = sphere(r_back, make_portion(0, PI / 2 + phi), detail);
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auto &&s2 = sphere(r_pin, make_portion(PI / 2 + phi, PI), detail);
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for (auto &p : s2.vertices) p.z() += h;
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its_merge(mesh, s1);
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its_merge(mesh, s2);
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for (size_t idx1 = s1.vertices.size() - steps, idx2 = s1.vertices.size();
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idx1 < s1.vertices.size() - 1; idx1++, idx2++) {
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coord_t i1s1 = coord_t(idx1), i1s2 = coord_t(idx2);
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coord_t i2s1 = i1s1 + 1, i2s2 = i1s2 + 1;
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mesh.indices.emplace_back(i1s1, i2s1, i2s2);
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mesh.indices.emplace_back(i1s1, i2s2, i1s2);
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}
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auto i1s1 = coord_t(s1.vertices.size()) - coord_t(steps);
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auto i2s1 = coord_t(s1.vertices.size()) - 1;
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auto i1s2 = coord_t(s1.vertices.size());
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auto i2s2 = coord_t(s1.vertices.size()) + coord_t(steps) - 1;
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mesh.indices.emplace_back(i2s2, i2s1, i1s1);
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mesh.indices.emplace_back(i1s2, i2s2, i1s1);
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return mesh;
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}
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indexed_triangle_set halfcone(double baseheight,
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double r_bottom,
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double r_top,
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const Vec3d &pos,
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size_t steps)
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{
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assert(steps > 0);
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if (baseheight <= 0 || steps <= 0) return {};
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indexed_triangle_set base;
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double a = 2 * PI / steps;
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auto last = int(steps - 1);
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Vec3d ep{pos.x(), pos.y(), pos.z() + baseheight};
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for (size_t i = 0; i < steps; ++i) {
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double phi = i * a;
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auto x = float(pos.x() + r_top * std::cos(phi));
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auto y = float(pos.y() + r_top * std::sin(phi));
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base.vertices.emplace_back(x, y, float(ep.z()));
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}
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for (size_t i = 0; i < steps; ++i) {
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double phi = i * a;
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auto x = float(pos.x() + r_bottom * std::cos(phi));
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auto y = float(pos.y() + r_bottom * std::sin(phi));
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base.vertices.emplace_back(x, y, float(pos.z()));
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}
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base.vertices.emplace_back(pos.cast<float>());
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base.vertices.emplace_back(ep.cast<float>());
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auto &indices = base.indices;
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auto hcenter = int(base.vertices.size() - 1);
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auto lcenter = int(base.vertices.size() - 2);
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auto offs = int(steps);
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for (int i = 0; i < last; ++i) {
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indices.emplace_back(i, i + offs, offs + i + 1);
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indices.emplace_back(i, offs + i + 1, i + 1);
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indices.emplace_back(i, i + 1, hcenter);
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indices.emplace_back(lcenter, offs + i + 1, offs + i);
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}
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indices.emplace_back(0, last, offs);
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indices.emplace_back(last, offs + last, offs);
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indices.emplace_back(hcenter, last, 0);
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indices.emplace_back(offs, offs + last, lcenter);
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return base;
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}
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}} // namespace Slic3r::sla
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