!****h* General_VKN/Bez6
! NAME
!   Bez6 -- Module to produce bezier curves with 6 control points. 
!   [Bez6.MBS]
! DESCRIPTION
!  The steps followed are:
!  * Input the 6 3D coordinate locations for the nodes defining the curve.
!  * Create points at each node location.
!  * Connect the nodes with lines
!  * Place points at each line mid-point & connect lines between mid-points.
!  * Place points at quarter points & connect quarter point lines.
!  * Place mid-points on each line defining tangent points at each curve 
!   connection node
!  * Place the Bezier curve connecting all the tangent points using 
!   cur_conic().
!  * Get location of tangent point preceding point #1 for return
! SOURCE

GLOBAL GEOMETRY MODULE Bez6(
   VECTOR 	pt1 >"Enter Pt #1", ! Starting (1st) Chord Point
           	pt2 >"Enter Pt #2", ! 2nd, etc.
          	pt3 >"Enter Pt #3", 
          	pt4 >"Enter Pt #4",
          	pt5 >"Enter Pt #5",
          	pt6 >"Enter Pt #6";
   VAR VECTOR Tngt1);		  ! Returns tangent pt for pt1
!***
!
!    Copyright 2006, John J. Hughes (Email: n4yvt@arrl.net)
!
!    This source code file is part of the 'NGBproject' files which   
!    execute interactively under the 'VARKON' program, which is   
!    distributed under the terms of the GNU General Public License.
!
!    The 'NGBproject' files are also distributed under the terms of  
!    the GNU GeneralPublic License.  See the GNU General Public License n
!    included ithe file name "COPYING.txt" in the Varkon ./app/NGB/doc 
!    directory for more details.
!

BEGINMODULE

!*********************************************************************** 
!  ~ Create points at each node location. !-----------------------------------------------------------------------

  poi_free(#30,pt1:BLANK=0);
  poi_free(#40,pt2:BLANK=0);
  poi_free(#50,pt3:BLANK=0);
  poi_free(#60,pt4:BLANK=0);
  poi_free(#70,pt5:BLANK=0);
  poi_free(#80,pt6:BLANK=0);

!*********************************************************************** 
!  ~ Connect the nodes with lines !-----------------------------------------------------------------------

  lin_free(#130,on(#30), on(#40):BLANK=0);
  lin_free(#150,on(#40), on(#50):BLANK=0);
  lin_free(#160,on(#50), on(#60):BLANK=0);
  lin_free(#170,on(#60), on(#70):BLANK=0);
  lin_free(#180,on(#70), on(#80):BLANK=0);

!*********************************************************************** 
!  ~ Get location of tangent point preceding point #1 !-----------------------------------------------------------------------

   Tngt1:=pt1 - 0.25*tang(#130);
   poi_free(#184,Tngt1:BLANK=0);

!*********************************************************************** 
!  ~ Place points at each line mid-point & connect lines 
!  ~ between mid-points. !-----------------------------------------------------------------------

  poi_free(#190,on(#130, 0.5):BLANK=1);
  poi_free(#200,on(#150, 0.5):BLANK=1);
  poi_free(#210,on(#160, 0.5):BLANK=1);
  poi_free(#220,on(#170, 0.5):BLANK=1);
  poi_free(#230,on(#180, 0.5):BLANK=1);
  lin_free(#240,on(#190), on(#200):BLANK=1);
  lin_free(#250,on(#200), on(#210):BLANK=1);
  lin_free(#260,on(#210), on(#220):BLANK=1);
  lin_free(#270,on(#220), on(#230):BLANK=1);

!*********************************************************************** 
!  ~ Place points at quarter points & connect quarter oint lines. !-----------------------------------------------------------------------

  poi_free(#280,on(#130, 0.25):BLANK=1);
  poi_free(#290,on(#240, 0.25):BLANK=1);
  poi_free(#300,on(#250, 0.25):BLANK=1);
  poi_free(#310,on(#260, 0.25):BLANK=1);
  poi_free(#320,on(#270, 0.25):BLANK=1);
  poi_free(#330,on(#240, 0.75):BLANK=1);
  poi_free(#340,on(#250, 0.75):BLANK=1);
  poi_free(#350,on(#260, 0.75):BLANK=1);
  poi_free(#360,on(#270, 0.75):BLANK=1);
  poi_free(#370,on(#180, 0.75):BLANK=1);
  poi_free(#600,on(#180, 0.95):BLANK=1);
  lin_free(#380,on(#280), on(#290):BLANK=1);
  lin_free(#390,on(#330), on(#300):BLANK=1);
  lin_free(#400,on(#340), on(#310):BLANK=1);
  lin_free(#410,on(#350), on(#320):BLANK=1);
  lin_free(#420,on(#360), on(#370):BLANK=1);

!*********************************************************************** 
!  ~ Place mid-points on each line defining tangent points at each 
!  ~ curve connection node !-----------------------------------------------------------------------

  poi_free(#430,on(#380, 0.5):BLANK=1);
  poi_free(#440,on(#240, 0.5):BLANK=1);
  poi_free(#450,on(#390, 0.5):BLANK=1);
  poi_free(#460,on(#250, 0.5):BLANK=1);
  poi_free(#470,on(#260, 0.5):BLANK=1);
  poi_free(#480,on(#410, 0.5):BLANK=1);
  poi_free(#490,on(#270, 0.5):BLANK=1);
  poi_free(#500,on(#420, 0.5):BLANK=1);
  poi_free(#510,on(#400, 0.5):BLANK=1); 

!*********************************************************************** 
!  ~ Place the Bezier curve connection all the tangent points. !-----------------------------------------------------------------------

  cur_conic(#530,"FREE",
   on(#30), on(#280),0.55,
   on(#430),on(#290),0.55,
   on(#440),on(#330),0.55,
   on(#450),on(#300),0.55, 
   on(#460),on(#340),0.55, 
   on(#510),on(#310),0.55, 
   on(#470),on(#350),0.55,
   on(#480),on(#320),0.55,
   on(#490),on(#360),0.55,
   on(#500),on(#370),0.55,
   on(#600),on(#370),0.55);

ENDMODULE