void gradient_mat(rvec grad, int nmat, t_matrix mat[])
{
int m;
for(m=0; m<nmat; m++)
gradient_map(grad, mat[m].nmap, mat[m].map);
}
//pair<double, double> --> current energy seam, gradient value
std::vector<std::vector<std::pair<double, double> > > calculate_gradient(std::vector<std::vector<double> > luminosity_map) {
std::vector<std::vector<std::pair<double, double> > > gradient_map(luminosity_map.size(),
std::vector<std::pair<double, double> >(luminosity_map[0].size(),
std::pair<double, double>(DBL_MAX, DBL_MAX)));
int width = luminosity_map[0].size();
int height = luminosity_map.size();
for (int i = 0; i < luminosity_map.size(); i++) {
for (int j = 0; j < luminosity_map[i].size(); j++) {
double current_val = luminosity_map[i][j];
double u = valid_coord(std::pair<int, int>(i - 1, j), width, height) ? luminosity_map[i - 1][j] : current_val;
double d = valid_coord(std::pair<int, int>(i + 1, j), width, height) ? luminosity_map[i + 1][j] : current_val;
double l = valid_coord(std::pair<int, int>(i, j - 1), width, height) ? luminosity_map[i][j - 1] : current_val;
double r = valid_coord(std::pair<int, int>(i, j + 1), width, height) ? luminosity_map[i][j + 1] : current_val;
double dx = r - l;
double dy = u - d;
gradient_map[i][j] = std::pair<double, double>(DBL_MAX, pythagorean(dx, dy));
if (i == 0) {
gradient_map[i][j].first = gradient_map[i][j].second;
}
}
}
return gradient_map;
}
