Source PostScript (segment_inter_planz.pps)

%% syntaxe : A B k segment_inter_planz --> array true ou false
/segment_inter_planz {
4 dict begin
   /k exch def
   /B defpoint3d
   /A defpoint3d
   A /zA exch def pop pop
   B /zB exch def pop pop
   zA k sub zB k sub mul dup 0 gt {
      %% pas d intersection
      pop
      false
   } {
      0 eq {
         %% intersection en A ou en B
         [ 
            zA k eq {A} if
            zB k eq {B} if
         ] true
      } {
         %% intersection entre A et B
         [
            A B vecteur3d
            k zA sub zB zA sub div mulv3d
            A addv3d
         ] true
      } ifelse
   } ifelse
end
} def