!**********************************************************
!*

  BASIC GEOMETRY MODULE pvalf(
      REF spine      >"ID of spine curve !";
      FLOAT pv1:=0.5 >"Fore P-value !";
      FLOAT pv2:=0.5 >"Mid  P-value !";
      FLOAT pv3:=0.5 >"Aft  P-value !";
  VAR REF   pvalf);

!*  This module creates a P-value function pvalf=#1 used
!*  to control the shape of the hull. A P-value function
!*  is a 2D curve that defines the relationship between
!*  points on the spine and the P-value of the conic
!*  segment that defines the surface in the point.
!*
!*  This program is free software; you can redistribute it and/or
!*  modify it under the terms of the GNU General Public License
!*  as published by the Free Software Foundation; either version 2
!*  of the License, or (at your option) any later version.
!*
!*  This program is distributed in the hope that it will be useful,
!*  but WITHOUT ANY WARRANTY; without even the implied warranty of
!*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!*  GNU General Public License for more details.
!*
!*  You should have received a copy of the GNU General Public License
!*  along with this program; if not, write to the Free Software
!*  Foundation, Inc., 59 Temple Place - Suite 330, Boston,
!*  MA  02111-1307, USA.
!*
!*  (C)Microform AB 2000, J.Kjellander
!*
!**********************************************************

   FLOAT  spine_length;
   VECTOR p1,p2;

BEGINMODULE

!*
!***A P-value function always starts in X=0 and ends
!***in X=the length of the spine.
!*
   p1:=startp(spine);
   p2:=endp(spine);
   spine_length:=abs(p2.x-p1.x);
!*
!***Create the P-value function as a single segment planar curve.
!*
   cur_spline(#1,"PROJ",
                 vec(0,pv1),,
                 vec(spine_length/2,pv2),,
                 vec(spine_length,pv3)
                 :BLANK=1,PEN=6);
   pvalf:=global_ref(#1);

ENDMODULE