%% $Id: pst-nutation.pro 1198 2025-12-20 13:27:56Z herbert $
%%
%% This is file `pst-nutation.pro',
%%
%% Jürgen Gilg & Manuel Luque & Herbert Voß <hvoss@tug.org> 
%%
%% This program can be redistributed and/or modified under the terms
%% of the LaTeX Project Public License Distributed from CTAN archives
%% in directory macros/latex/base/lppl.txt.
%%
%% version 0.01 / 2025-12-20
%
/pst-parallel {
  /TabPtsParallel [
  0 1 360{
    /latitude exch def
   [
    r latitude cos mul phi cos mul
    r latitude sin mul phi cos mul
    r phi sin mul
    ]
    } for
     ] def
  gsave
  Parallele
  grestore
} def

/Parallele {
   linecolor
   linestyle
   solidlinewidth setlinewidth
   0 1 TabPtsParallel length 2 sub {/i exch def
     TabPtsParallel i get aload pop       /Point1 defpoint3d
     TabPtsParallel i 1 add get aload pop /Point2 defpoint3d
       Point1
       GetCamPos
       vecteur3d
       Point1 scalprod3d 0 gt
       Point2
       GetCamPos
       vecteur3d
       Point2 scalprod3d 0 gt and {
         Point1 3dto2d xunit mul exch xunit mul exch moveto
         Point2 3dto2d xunit mul exch xunit mul exch lineto
         stroke
       } if
     } for
   projectionsifacevisible {
     0 3 TabPtsParallel length 3 sub {/i exch def
     TabPtsParallel i get aload pop       /Point1 defpoint3d
       Point1
       GetCamPos
       vecteur3d
       Point1 scalprod3d 0 le
        {
       Point1 3dto2d xunit mul exch xunit mul exch solidlinewidth 2 div 0 360 arc fill
       } if
     } for
   }if
} def

/pst-meridian {
  /TabPtsMeridian [
  0 1 360{
    /longitude exch def
   [
    r theta cos mul longitude cos mul
    r theta sin mul longitude cos mul
    r longitude sin mul
    ]
    } for
     ] def
  gsave
  Meridian
  grestore
} def

/Meridian {
   linecolor
   linestyle
   solidlinewidth setlinewidth
   0 1 TabPtsMeridian length 2 sub {/i exch def
    TabPtsMeridian i get aload pop       /Point1 defpoint3d
    TabPtsMeridian i 1 add get aload pop /Point2 defpoint3d
       Point1
       GetCamPos
       vecteur3d
       Point1 scalprod3d 0 gt
       Point2
       GetCamPos
       vecteur3d
       Point2 scalprod3d 0 gt and {
       Point1 3dto2d xunit mul exch xunit mul exch moveto
       Point2 3dto2d xunit mul exch xunit mul exch lineto
       stroke
       } if
       } for
projectionsifacevisible {
   0 2 TabPtsMeridian length 2 sub {/i exch def
    TabPtsMeridian i get aload pop       /Point1 defpoint3d       
       Point1
       GetCamPos
       vecteur3d
       Point1 scalprod3d 0 le
             {
       Point1 3dto2d xunit mul exch xunit mul exch solidlinewidth 2 div 0 360 arc fill
             } if
       } for
       } if
   } def