tests/test-up.cxx

   1 // do some test relating to the concept of "up"
   2
   3 #ifdef HAVE_CONFIG_H
   4 #  include <config.h>
   5 #endif
   6
   7 #include <simgear/compiler.h>
   8
   9 #include <iostream>
  10
  11 #include <plib/sg.h>
  12
  13 #include <simgear/constants.h>
  14 #include <simgear/math/sg_geodesy.hxx>
  15
  16 using std::cout;
  17 using std::endl;
  18
  19 int main() {
  20     // for each lat/lon given in goedetic coordinates, calculate
  21     // geocentric coordinates, cartesian coordinates, the local "up"
  22     // vector (based on original geodetic lat/lon), as well as the "Z"
  23     // intercept (for which 0 = center of earth)
  24
  25
  26     double lon = 0;
  27     double alt = 0;
  28
  29     for ( double lat = 0; lat <= 90; lat += 5.0 ) {
  30         cout << "lon = " << lon << "  geod lat = " << lat;
  31
  32         double sl_radius, lat_geoc;
  33         sgGeodToGeoc( lat * SGD_DEGREES_TO_RADIANS, alt, &sl_radius, &lat_geoc );
  34         cout << "  geoc lat = " << lat_geoc * SGD_RADIANS_TO_DEGREES << endl;
  35
  36         Point3D pgd( lon * SGD_DEGREES_TO_RADIANS, lat * SGD_DEGREES_TO_RADIANS, 0.0 );
  37         Point3D pc = sgGeodToCart( pgd );
  38         cout << "  cartesian = " << pc << endl;
  39
  40         sgdMat4 GEOD_UP;
  41         sgdVec3 geod_up;
  42         sgdMakeRotMat4( GEOD_UP, lon, 0.0, -lat );
  43         sgdSetVec3( geod_up, GEOD_UP[0][0], GEOD_UP[0][1], GEOD_UP[0][2] );
  44         cout << "  geod up = " << geod_up[0] << ", " << geod_up[1] << ", "
  45              << geod_up[2] << endl;
  46
  47         sgdMat4 GEOC_UP;
  48         sgdVec3 geoc_up;
  49         sgdMakeRotMat4( GEOC_UP, lon, 0.0, -lat_geoc * SGD_RADIANS_TO_DEGREES );
  50         sgdSetVec3( geoc_up, GEOC_UP[0][0], GEOC_UP[0][1], GEOC_UP[0][2] );
  51         cout << "  geoc up = " << geoc_up[0] << ", " << geoc_up[1] << ", "
  52              << geoc_up[2] << endl;
  53
  54         double slope = geod_up[2] / geod_up[0];
  55         double intercept = pc.z() - slope * pc.x();
  56         cout << "  Z intercept (based on geodetic up) = " << intercept << endl;
  57
  58         slope = geoc_up[2] / geoc_up[0];
  59         intercept = pc.z() - slope * pc.x();
  60         cout << "  Z intercept (based on geocentric up) = " << intercept << endl;
  61
  62    }
  63
  64     return 0;
  65 }