IGL_INLINE int igl::embree::unproject_in_mesh(
const Eigen::Vector2f& pos,
const Eigen::Matrix4f& model,
const Eigen::Matrix4f& proj,
const Eigen::Vector4f& viewport,
const EmbreeIntersector & ei,
Eigen::PlainObjectBase<Derivedobj> & obj,
std::vector<igl::embree::Hit > & hits)
{
using namespace igl;
using namespace std;
using namespace Eigen;
// Source and direction on screen
Vector3f win_s(pos(0),pos(1),0);
Vector3f win_d(pos(0),pos(1),1);
// Source, destination and direction in world
Vector3f s,d,dir;
s = igl::unproject(win_s,model,proj,viewport);
d = igl::unproject(win_d,model,proj,viewport);
dir = d-s;
// Shoot ray, collect all hits (could just collect first two)
int num_rays_shot;
hits.clear();
ei.intersectRay(s,dir,hits,num_rays_shot);
switch(hits.size())
{
case 0:
break;
case 1:
{
obj = (s + dir*hits[0].t).cast<typename Derivedobj::Scalar>();
break;
}
case 2:
default:
{
obj = 0.5*((s + dir*hits[0].t) + (s + dir*hits[1].t)).cast<typename Derivedobj::Scalar>();
break;
}
}
return hits.size();
}
IGL_INLINE void igl::reorient_facets_raycast(
const Eigen::PlainObjectBase<DerivedV> & V,
const Eigen::PlainObjectBase<DerivedF> & F,
int rays_total,
int rays_minimum,
bool facet_wise,
bool use_parity,
bool is_verbose,
Eigen::PlainObjectBase<DerivedI> & I,
Eigen::PlainObjectBase<DerivedC> & C)
{
using namespace Eigen;
using namespace std;
assert(F.cols() == 3);
assert(V.cols() == 3);
// number of faces
const int m = F.rows();
MatrixXi FF = F;
if (facet_wise) {
C.resize(m);
for (int i = 0; i < m; ++i) C(i) = i;
} else {
if (is_verbose) cout << "extracting patches... ";
bfs_orient(F,FF,C);
}
if (is_verbose) cout << (C.maxCoeff() + 1) << " components. ";
// number of patches
const int num_cc = C.maxCoeff()+1;
// Init Embree
EmbreeIntersector ei;
ei.init(V.template cast<float>(),FF);
// face normal
MatrixXd N;
per_face_normals(V,FF,N);
// face area
Matrix<typename DerivedV::Scalar,Dynamic,1> A;
doublearea(V,FF,A);
double area_total = A.sum();
// determine number of rays per component according to its area
VectorXd area_per_component;
area_per_component.setZero(num_cc);
for (int f = 0; f < m; ++f)
{
area_per_component(C(f)) += A(f);
}
VectorXi num_rays_per_component(num_cc);
for (int c = 0; c < num_cc; ++c)
{
num_rays_per_component(c) = max<int>(static_cast<int>(rays_total * area_per_component(c) / area_total), rays_minimum);
}
rays_total = num_rays_per_component.sum();
// generate all the rays
if (is_verbose) cout << "generating rays... ";
uniform_real_distribution<float> rdist;
mt19937 prng;
prng.seed(time(nullptr));
vector<int > ray_face;
vector<Vector3f> ray_ori;
vector<Vector3f> ray_dir;
ray_face.reserve(rays_total);
ray_ori .reserve(rays_total);
ray_dir .reserve(rays_total);
for (int c = 0; c < num_cc; ++c)
{
if (area_per_component[c] == 0)
{
continue;
}
vector<int> CF; // set of faces per component
vector<double> CF_area;
for (int f = 0; f < m; ++f)
{
if (C(f)==c)
{
CF.push_back(f);
CF_area.push_back(A(f));
}
}
// discrete distribution for random selection of faces with probability proportional to their areas
discrete_distribution<int> ddist(CF.size(), 0, CF.size(), [&](double i){ return CF_area[static_cast<int>(i)]; }); // simple ctor of (Iter, Iter) not provided by the stupid VC11/12
for (int i = 0; i < num_rays_per_component[c]; ++i)
{
int f = CF[ddist(prng)]; // select face with probability proportional to face area
float s = rdist(prng); // random barycentric coordinate (reference: Generating Random Points in Triangles [Turk, Graphics Gems I 1990])
float t = rdist(prng);
float sqrt_t = sqrtf(t);
float a = 1 - sqrt_t;
float b = (1 - s) * sqrt_t;
float c = s * sqrt_t;
Vector3f p = a * V.row(FF(f,0)).template cast<float>().eval() // be careful with the index!!!
+ b * V.row(FF(f,1)).template cast<float>().eval()
+ c * V.row(FF(f,2)).template cast<float>().eval();
Vector3f n = N.row(f).cast<float>();
if (n.isZero()) continue;
// random direction in hemisphere around n (avoid too grazing angle)
Vector3f d;
while (true) {
d = random_dir().cast<float>();
float ndotd = n.dot(d);
if (fabsf(ndotd) < 0.1f)
{
continue;
}
if (ndotd < 0)
{
d *= -1.0f;
}
break;
}
ray_face.push_back(f);
ray_ori .push_back(p);
ray_dir .push_back(d);
if (is_verbose && ray_face.size() % (rays_total / 10) == 0) cout << ".";
}
}
if (is_verbose) cout << ray_face.size() << " rays. ";
// per component voting: first=front, second=back
vector<pair<float, float>> C_vote_distance(num_cc, make_pair(0, 0)); // sum of distance between ray origin and intersection
vector<pair<int , int >> C_vote_infinity(num_cc, make_pair(0, 0)); // number of rays reaching infinity
vector<pair<int , int >> C_vote_parity(num_cc, make_pair(0, 0)); // sum of parity count for each ray
if (is_verbose) cout << "shooting rays... ";
#pragma omp parallel for
for (int i = 0; i < (int)ray_face.size(); ++i)
{
int f = ray_face[i];
Vector3f o = ray_ori [i];
Vector3f d = ray_dir [i];
int c = C(f);
// shoot ray toward front & back
vector<Hit> hits_front;
vector<Hit> hits_back;
int num_rays_front;
int num_rays_back;
ei.intersectRay(o, d, hits_front, num_rays_front);
ei.intersectRay(o, -d, hits_back , num_rays_back );
if (!hits_front.empty() && hits_front[0].id == f) hits_front.erase(hits_front.begin());
if (!hits_back .empty() && hits_back [0].id == f) hits_back .erase(hits_back .begin());
if (use_parity) {
#pragma omp atomic
C_vote_parity[c].first += hits_front.size() % 2;
#pragma omp atomic
C_vote_parity[c].second += hits_back .size() % 2;
} else {
if (hits_front.empty())
{
#pragma omp atomic
C_vote_infinity[c].first++;
} else {
#pragma omp atomic
C_vote_distance[c].first += hits_front[0].t;
}
if (hits_back.empty())
{
#pragma omp atomic
C_vote_infinity[c].second++;
} else {
#pragma omp atomic
C_vote_distance[c].second += hits_back[0].t;
}
}
}
I.resize(m);
for(int f = 0; f < m; ++f)
{
int c = C(f);
if (use_parity) {
I(f) = C_vote_parity[c].first > C_vote_parity[c].second ? 1 : 0; // Ideally, parity for the front/back side should be 1/0 (i.e., parity sum for all rays should be smaller on the front side)
} else {
I(f) = (C_vote_infinity[c].first == C_vote_infinity[c].second && C_vote_distance[c].first < C_vote_distance[c].second) ||
C_vote_infinity[c].first < C_vote_infinity[c].second
? 1 : 0;
}
// To account for the effect of bfs_orient
if (F.row(f) != FF.row(f))
I(f) = 1 - I(f);
}
if (is_verbose) cout << "done!" << endl;
}