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stochastic_ray_tracing.cpp
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Sun, Apr 6, 05:21

stochastic_ray_tracing.cpp
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#include <post.h>
namespace post_p
{
void postprocessing::dump_stochastic_ray_tracing(char *filename, int num_rays)
{
f_srt = fopen(filename, "w");
stochastic_ray_tracing(filename, num_rays);
fclose(f_srt);
free(delta_x);
free(inv_delta_x);
free(nx);
free(idx_multiplicator);
}
void postprocessing::discretize_domain()
{
delta_x = (double*)malloc(sizeof(double)*dim());
inv_delta_x = (double*)malloc(sizeof(double)*dim());
nx = (int*)malloc(sizeof(int)*dim());
idx_multiplicator = (int*)malloc(sizeof(int)*dim());
for (int axis = 0; axis < dim(); axis++){
nx[axis] = (int)(L(axis));
}
for (int axis = 0; axis < dim(); axis++){
delta_x[axis] = L(axis)/nx[axis];
inv_delta_x[axis] = 1./delta_x[axis];
}
int total_nx = 1;
for (int axis = 0; axis < dim(); axis++){
total_nx *= nx[axis];
idx_multiplicator[axis] = 1;
}
for (int axis = 0; axis < dim(); axis++){
for (int i = axis; i < (dim()-1); i++)
idx_multiplicator[axis] *= nx[axis];
}
grid_config.resize(total_nx);
}
int postprocessing::get_idx_from_coords(std::vector<int> val)
{
int sum = 0;
for (int axis = 0; axis < dim(); axis++)
sum += val[axis]*idx_multiplicator[axis];
return sum;
}
void postprocessing::build_neighbour_lists()
{
std::vector<int> coords;
int index;
coords.resize(dim());
for (int i = 0; i < numParticles(); i++){
for (int axis = 0; axis < dim(); axis++)
coords[axis] = (int)(pos(i,axis) * inv_delta_x[axis]);
index = get_idx_from_coords(coords);
grid_config[index].push_back(i);
}
}
void postprocessing::get_neighbours(std::vector<int> &all_neighs, int *init_grid)
{
all_neighs.clear();
std::vector<int> temp_coords;
temp_coords.resize(dim());
int x_temp;
int y_temp;
int idx;
for (int x_diff = -1; x_diff <= 1; x_diff++){
x_temp = (init_grid[0]+x_diff);
x_temp += nx[0]*(x_temp < 0) - nx[0]*(x_temp >= nx[0]);
temp_coords[0] = x_temp;
for (int y_diff = -1; y_diff <= 1; y_diff++){
y_temp = (init_grid[1]+y_diff);
y_temp += nx[1]*(y_temp < 0) - nx[1]*(y_temp >= nx[1]);
temp_coords[1] = y_temp;
for (int k = 0; k < nx[2]; k++){
temp_coords[2] = k;
idx = get_idx_from_coords(temp_coords);
all_neighs.insert(all_neighs.end(), grid_config[idx].begin(), grid_config[idx].end());
}
}
}
}
std::pair<double, double> postprocessing::calculate_quad_eqn(double *sph_pos, double *temp_pos)
{
std::pair<double, double> tc;
double discriminant = 0.;
double q = 0.;
double p = 0.;
double diff = 0.;
q = get_periodic_image(sph_pos[2]-temp_pos[2], 2);
for (int axis = 0; axis < dim(); axis++)
diff += get_periodic_image(sph_pos[axis]-temp_pos[axis], axis)*get_periodic_image(sph_pos[axis]-temp_pos[axis], axis);
discriminant = (q*q) - diff + 0.25;
if (discriminant < 0.){
tc.first = -10.0;
tc.second = -10.0;
}
else{
tc.first = q - sqrt(discriminant);
tc.second = q + sqrt(discriminant);
}
return tc;
}
void postprocessing::print_chord_lengths(char *filename, std::vector<std::pair<double, double>> tc_list)
{
double tmp_offset;
if (tc_list.size() == 0){
fprintf(f_srt, "NaN\n");
//std::cout<<"yahaan aaya chutiye"<<std::endl;
}
else {
std::sort(tc_list.begin(), tc_list.end(), [](const std::pair<double, double>& a, const std::pair<double, double>& b) {return a.first < b.first;});
if (tc_list[0].first < 0.){
tmp_offset = tc_list[0].first;
for (int i = 0; i < tc_list.size(); i++){
tc_list[i].first -= tmp_offset;
tc_list[i].second -= tmp_offset;
}
}
for (int i = 0; i < (tc_list.size()-1); i++){
//fprintf(f_srt, "%lf,", tc_list[i+1].first-tc_list[i].second);
//std::cout<<"i="<<i<<std::endl;
fprintf(f_srt, "%lf,%lf,", tc_list[i+1].first,tc_list[i].second);
}
fprintf(f_srt, "%lf,%lf\n", tc_list[tc_list.size()-1].first,tc_list[tc_list.size()-1].second);
//std::cout<<"arrey gandu"<<std::endl;
//std::cout<<tc_list[0].first<<" "<<tc_list[0].second<<std::endl;
//fprintf(f_srt, "%lf\n", tc_list[0].first-tc_list[tc_list.size()-1].second+L(0));
}
}
void postprocessing::stochastic_ray_tracing(char *filename, int num_rays)
{
discretize_domain();
build_neighbour_lists();
std::vector<int> all_neighs;
std::pair<double, double> tc;
std::vector<std::pair<double, double>> tc_list;
double *temp_pos;
double *sph_pos;
int *int_grid;
temp_pos = (double*)malloc(sizeof(double)*dim());
sph_pos = (double*)malloc(sizeof(double)*dim());
int_grid = (int*)malloc(sizeof(int)*dim());
for (int i = 0; i < num_rays; i++) {
tc_list.clear();
temp_pos[0] = L(0)*dis(generator);
temp_pos[1] = L(1)*dis(generator);
temp_pos[2] = 0.;
for (int axis = 0; axis < dim(); axis++)
int_grid[axis] = inv_delta_x[axis]*temp_pos[axis];
get_neighbours(all_neighs, int_grid);
for (int id = 0; id < all_neighs.size(); id++){
for (int axis = 0; axis < dim(); axis++)
sph_pos[axis] = pos(all_neighs[id], axis);
tc = calculate_quad_eqn(sph_pos, temp_pos);
if (tc.first >= (-0.5*diameter(id)))
tc_list.push_back(tc);
}
print_chord_lengths(filename, tc_list);
}
free(sph_pos);
free(int_grid);
free(temp_pos);
}
}

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