/*!
\brief Calculate line length.
If projection is LL, the length is measured along the geodesic.
\param Points pointer to line_pnts structure geometry
\return line length
*/
double Vect_line_geodesic_length(const struct line_pnts *Points)
{
int j, dc;
double dx, dy, dz, dxy, len = 0;
dc = G_begin_distance_calculations();
if (Points->n_points < 2)
return 0;
for (j = 0; j < Points->n_points - 1; j++) {
if (dc == 2)
dxy =
G_geodesic_distance(Points->x[j], Points->y[j],
Points->x[j + 1], Points->y[j + 1]);
else {
dx = Points->x[j + 1] - Points->x[j];
dy = Points->y[j + 1] - Points->y[j];
dxy = hypot(dx, dy);
}
dz = Points->z[j + 1] - Points->z[j];
len += hypot(dxy, dz);
}
return len;
}
void plot(double lon1, double lat1, double lon2, double lat2,
int line_color, int text_color, double factor, const char *unit)
{
double distance;
double text_x, text_y;
double a, e2;
int nsteps = 1000;
int i;
/* establish the current graphics window */
D_setup(0);
G_get_ellipsoid_parameters(&a, &e2);
G_begin_geodesic_distance(a, e2);
D_use_color(line_color);
G_shortest_way(&lon1, &lon2);
if (lon1 != lon2) {
G_begin_geodesic_equation(lon1, lat1, lon2, lat2);
D_begin();
for (i = 0; i <= nsteps; i++) {
double lon = lon1 + (lon2 - lon1) * i / nsteps;
double lat = G_geodesic_lat_from_lon(lon);
if (i == 0)
D_move_abs(lon, lat);
else
D_cont_abs(lon, lat);
}
D_end();
D_stroke();
text_x = (lon1 + lon2) / 2;
text_y = G_geodesic_lat_from_lon(text_x);
}
else {
D_line_abs(lon1, lat1, lon2, lat2);
text_x = (lon1 + lon2) / 2;
text_y = (lat1 + lat2) / 2;
}
if (text_color != -1) {
double t, b, l, r;
char buf[100];
D_text_size(10, 10);
distance = G_geodesic_distance(lon1, lat1, lon2, lat2);
sprintf(buf, "%.0f %s", distance / factor, unit);
D_pos_abs(text_x, text_y);
D_get_text_box(buf, &t, &b, &l, &r);
if (t - D_get_u_north() > 0)
text_y -= t - D_get_u_north();
if (b - D_get_u_south() < 0)
text_y -= b - D_get_u_south();
if (r - D_get_u_east() > 0)
text_x -= r - D_get_u_east();
if (l - D_get_u_west() < 0)
text_x -= l - D_get_u_west();
D_use_color(text_color);
D_pos_abs(text_x, text_y);
D_text(buf);
}
}
