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eudist_cpp.cxx
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eudist_cpp.cxx
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#include "eudist_cpp.hxx"
#include <cmath>
#include <stdexcept>
#include <vector>
#include <cstdio>
double dot_dot(const double *a, const double *b, int n) {
double result = 0;
for (int i = 0; i < n; ++i) {
auto diff = a[i] - b[i];
result += diff * diff;
}
return sqrt(result);
}
double dot_prod(const double *a, const double *b, int n) {
double result = 0;
for (int i = 0; i < n; ++i) {
result += a[i] * b[i];
}
return result;
}
Plane::Plane(const double *p0, const double *p1, const double *p2, int n)
: norm(nullptr), dim(n) {
if (dim == 3) {
double v0[3], v1[3];
for (int i = 0; i < dim; ++i) {
v0[i] = p1[i] - p0[i];
v1[i] = p2[i] - p0[i];
}
norm = new double[dim];
norm[0] = v0[1] * v1[2] - v0[2] * v1[1];
norm[1] = v0[2] * v1[0] - v0[0] * v1[2];
norm[2] = v0[0] * v1[1] - v0[1] * v1[0];
d = 0;
normsq = 0;
for (int i = 0; i < dim; ++i) {
d -= norm[i] * p0[i];
normsq += norm[i] * norm[i];
}
normlen = sqrt(normsq);
}
}
Plane::~Plane() { delete[] norm; }
double Plane::dist(const double *dot) {
if (dim == 2) {
return 0.;
}
return fabs(dot_prod(dot, norm, dim) + d) / normlen;
}
double Plane::signed_dist(const double *dot) {
if (dim == 2) {
return 0.;
}
return (dot_prod(dot, norm, dim) + d) / normlen;
}
void Plane::info() {
printf("Dim: %d\n", dim);
printf("Norm: %.4f %.4f %.4f\n", norm[0], norm[1], norm[2]);
printf("Distance: %.4f\n", d / normlen);
}
const double *Plane::project(const double *dot) {
// Project a dot onto this plane
if (dim == 2) {
return dot;
}
auto ret = new double[dim];
auto fac = (dot_prod(dot, norm, dim) + d) / normsq;
for (int i = 0; i < 3; ++i) {
ret[i] = dot[i] - norm[i] * fac;
}
return ret;
}
inline double is_left(const double *P0, const double *P1, const double *P2) {
return ((P1[0] - P0[0]) * (P2[1] - P0[1]) -
(P2[0] - P0[0]) * (P1[1] - P0[1]));
}
int winding_number(const double *points, const double *dot,
const int num_pnts) {
int wn = 0;
for (int i = 0; i < num_pnts; ++i) {
const int offset = 2 * i;
const int next = (i == num_pnts - 1) ? 0 : offset + 2;
if (points[offset + 1] <= dot[1]) {
if (points[next + 1] > dot[1]) {
if (is_left(points + offset, points + next, dot) > 0) {
++wn;
}
}
} else {
if (points[next + 1] <= dot[1]) {
if (is_left(points + offset, points + next, dot) < 0) {
--wn;
}
}
}
}
return wn;
}
double line_segment_dot(const double *lp0, const double *lp1, const double *dot,
const int n) {
// Calculate the distance between the line segment defined by two
// points in line and a dot.
std::vector<double> v, w;
v.resize(n);
w.resize(n);
for (int i = 0; i < n; ++i) {
v[i] = lp1[i] - lp0[i];
w[i] = dot[i] - lp0[i];
}
auto c1 = dot_prod(w.data(), v.data(), n);
if (c1 < 0) {
return dot_dot(dot, lp0, n);
}
auto c2 = dot_prod(v.data(), v.data(), n);
if (c2 <= c1) {
return dot_dot(dot, lp1, n);
}
auto p = c1 / c2;
for (int i = 0; i < n; ++i) {
v[i] *= p;
v[i] += lp0[i];
}
return dot_dot(v.data(), dot, n);
}
double polygon_dot(const double *points, const double *dot, const int num_pnts,
const int dims, const bool check_planar) {
// def polygon_dot(np.ndarray points,np.ndarray dot, check_planar=True):
if (num_pnts == 1) {
return dot_dot(points, dot, dims);
}
if (num_pnts == 2) {
return line_segment_dot(points, points + dims, dot, dims);
}
auto plane = Plane(points, points + dims, points + dims + dims, dims);
if (check_planar) {
// if len(points) > 3 and len(dot) > 2:
// # get an estimate of the length scales involved
// if not _is_planar(points, atol=0, rtol=1e-3):
// raise RuntimeError(f"Point of polygon are not in a plane!")
}
// Simple projection onto 2D-plane. Drop main component of orthogonal vector
const double *pnts;
const double *_dot;
if (dims == 3) {
auto tmp = new double[num_pnts * 2];
double *nrm = plane.norm;
int i0, i1;
if (nrm[0] > nrm[1]) { // 1 is not largest
if (nrm[0] > nrm[2]) {
// 0 is largest
i0 = 1;
i1 = 2;
} else {
// 2 is largest
i0 = 0;
i1 = 1;
}
} else { // 0 is not largest
if (nrm[1] > nrm[2]) {
// 1 is largest
i0 = 0;
i1 = 2;
} else {
// 2 is largest
i0 = 0;
i1 = 1;
}
}
for (int i = 0; i < num_pnts; ++i) {
tmp[2 * i] = points[i * 3 + i0];
tmp[2 * i + 1] = points[i * 3 + i1];
}
pnts = tmp;
auto proj = plane.project(dot);
tmp = new double[2];
tmp[0] = proj[i0];
tmp[1] = proj[i1];
_dot = tmp;
delete[] proj;
} else if (dims == 2) {
pnts = points;
_dot = dot;
} else {
throw std::runtime_error("Unexpected number of dimension - only 2D and 3D "
"Vectors are supported.");
}
auto wn = winding_number(pnts, _dot, num_pnts);
if (dims == 3) {
delete[] _dot;
delete[] pnts;
}
if (wn == 0) {
double min =
line_segment_dot(points + (num_pnts - 1) * dims, points, dot, dims);
for (int i = 0; i < num_pnts - 1; ++i) {
auto ptr = points + i * dims;
double tmp = line_segment_dot(ptr, ptr + dims, dot, dims);
if (tmp < min) {
min = tmp;
}
}
return min;
}
return plane.dist(dot);
}
void PolyMesh::add_to_outer(int &pos, int i, int j) {
int iin = i * ny + j;
outer[pos++] = datax[iin];
outer[pos++] = datay[iin];
};
PolyMesh::PolyMesh(const double *datax, const double *datay, int nx, int ny)
: nx(nx), ny(ny), datax(datax), datay(datay),
num_cells((nx - 1) * (ny - 1)) {
bounds = new double[num_cells * 2 * 4];
outer = new double[(nx + ny) * 2 * 2];
int pos = 0;
for (int i = 0; i < nx - 1; ++i) {
for (int j = 0; j < ny - 1; ++j) {
int iin = i * ny + j;
bounds[pos++] = datax[iin];
bounds[pos++] = datay[iin];
bounds[pos++] = datax[iin + 1];
bounds[pos++] = datay[iin + 1];
bounds[pos++] = datax[iin + ny + 1];
bounds[pos++] = datay[iin + ny + 1];
bounds[pos++] = datax[iin + ny];
bounds[pos++] = datay[iin + ny];
}
}
{
int pos = 0;
int i = 0;
int j = 0;
for (; i < nx - 1; ++i) {
add_to_outer(pos, i, j);
}
for (; j < ny - 1; ++j) {
add_to_outer(pos, i, j);
}
for (; i > 0; --i) {
add_to_outer(pos, i, j);
}
for (; j > 0; --j) {
add_to_outer(pos, i, j);
}
}
}
PolyMesh::~PolyMesh() { delete[] bounds; }
int PolyMesh::find_cell(const double *dot, int guess) {
if (guess >= 0) {
for (int i = -1; i < 2; ++i) {
for (int j = -1; j < 2; ++j) {
int pos = guess + i + (ny - 1) * j;
if (pos >= 0 && pos < num_cells) {
if (winding_number(bounds + pos * 8, dot, 4)) {
return pos;
}
}
}
}
}
if (winding_number(outer, dot, (nx + ny - 2) * 2) == 0) {
return -1;
}
for (int pos = 0; pos < num_cells; ++pos) {
if (winding_number(bounds + pos * 8, dot, 4)) {
return pos;
}
}
return -1;
}