libs/pbd/cartesian.cc

   1 /*
   2     Copyright (C) 2010 Paul Davis
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17 */
  18
  19 #include <iostream>
  20 #include <math.h>
  21
  22 #include "pbd/cartesian.h"
  23
  24 using namespace std;
  25
  26 void
  27 PBD::spherical_to_cartesian (double azi, double ele, double len, double& x, double& y, double& z)
  28 {
  29         /* convert from cylindrical coordinates in degrees to cartesian */
  30
  31         static const double atorad = 2.0 * M_PI / 360.0 ;
  32
  33         if (len == 0.0) {
  34                 len = 1.0;
  35         }
  36
  37         x = len * cos (azi * atorad) * cos (ele * atorad);
  38         y = len * sin (azi * atorad) * cos (ele * atorad);
  39         z = len * sin (ele * atorad);
  40 }
  41
  42 void
  43 PBD::cartesian_to_spherical (double x, double y, double z, double& azimuth, double& elevation, double& length)
  44 {
  45 #if 1
  46         /* converts cartesian coordinates to cylindrical in degrees*/
  47
  48         double rho, theta, phi;
  49
  50         rho = sqrt (x*x + y*y + z*z);
  51         phi = acos (1.0/rho);
  52         theta = atan2 (y, x);
  53
  54         /* XXX for now, clamp phi to zero */
  55
  56         phi = 0.0;
  57
  58         if (theta < 0.0) {
  59                 azimuth = 180.0 - (180.0 * (theta / M_PI)); /* LHS is negative */
  60         } else {
  61                 azimuth = 180.0 * (theta / M_PI);
  62         }
  63
  64         if (phi < 0.0) {
  65                 elevation = 180.0 - (180.0 * (phi / M_PI)); /* LHS is negative */
  66         } else {
  67                 elevation = 180.0 * (phi /  M_PI);
  68         }
  69
  70         length = rho;
  71 #else
  72         /* converts cartesian coordinates to cylindrical in degrees*/
  73
  74         const double atorad = 2.0 * M_PI / 360.0;
  75         double atan_y_per_x, atan_x_pl_y_per_z;
  76         double distance;
  77
  78         if (x == 0.0) {
  79                 atan_y_per_x = M_PI / 2;
  80         } else {
  81                 atan_y_per_x = atan2 (y,x);
  82         }
  83
  84         if (y < 0.0) {
  85                 /* below x-axis: atan2 returns 0 .. -PI (negative) so convert to degrees and ADD to 180 */
  86                 azimuth = 180.0 + (atan_y_per_x / (M_PI/180.0) + 180.0);
  87         } else {
  88                 /* above x-axis: atan2 returns 0 .. +PI so convert to degrees */
  89                 azimuth = atan_y_per_x / atorad;
  90         }
  91
  92         distance = sqrt (x*x + y*y);
  93
  94         if (z == 0.0) {
  95                 atan_x_pl_y_per_z = 0.0;
  96         } else {
  97                 atan_x_pl_y_per_z = atan2 (z,distance);
  98         }
  99
 100         if (distance == 0.0) {
 101                 if (z < 0.0) {
 102                         atan_x_pl_y_per_z = -M_PI/2.0;
 103                 } else if (z > 0.0) {
 104                         atan_x_pl_y_per_z = M_PI/2.0;
 105                 }
 106         }
 107
 108         elevation = atan_x_pl_y_per_z / atorad;
 109
 110         // distance = sqrtf (x*x + y*y + z*z);
 111 #endif
 112 }
 113