//===========================================================================
// Copyright (C) 1998, 2000-2007, 2010, 2011, 2012 SINTEF ICT, Applied
// Mathematics, Norway.
//
// This file is part of GoTools
//
// 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 version 2 of the License. 
//
// 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, see <http://www.gnu.org/licenses>
//
// Contact information: E-mail: tor.dokken@sintef.no                      
// SINTEF ICT, Department of Applied Mathematics,                         
// P.O. Box 124 Blindern,                                                 
// 0314 Oslo, Norway.                                                     
//
// Other licenses are also available for this software, notably licenses
// for:
// - Building commercial software.                                        
// - Building software whose source code you wish to keep private.        
//===========================================================================

#include "sisl-copyright.h"

/*
 *
 * $Id: s1786.c,v 1.5 2005-02-28 09:04:49 afr Exp $
 *
 */
#define S1786

#include "sislP.h"

typedef  void (*fevalcProc)(
#if defined(SISLNEEDPROTOTYPES)
                        SISLCurve *,
                        int,
                        double ,
                        int *,
                        double [],
                        int *
#endif
);



#if defined(SISLNEEDPROTOTYPES)
static void s1786_s9relax(fevalcProc fevalc1,
			  fevalcProc fevalc2,
			  SISLCurve *,SISLCurve *,int,double,double,int *,
			  double [],double,double *,int *,double [],int *);
#else
static void s1786_s9relax();
#endif

#if defined(SISLNEEDPROTOTYPES)
void
   s1786(SISLCurve *pc1,SISLCurve *pc2,double aepsge,double epar1[],double epar2[],int *jstat)
#else
void s1786(pc1,pc2,aepsge,epar1,epar2,jstat)
   SISLCurve  *pc1;
   SISLCurve  *pc2;
     double aepsge;
     double epar1[];
     double epar2[];
     int    *jstat;
#endif
/*
*********************************************************************
*
*********************************************************************
*
* PURPOSE    : Test if the curves coincide between two intersection points.
*              This function is used when the first derivative
*              for the curves are matching in both intersection points.
*
*
* INPUT      : pc1      - Pointer to the first curve.
*              pc2      - Pointer to the second curve..
*              aepsge   - Geometry resolution.
*              epar1[2] - Parameter values for the first intersection point.
*              epar2[2] - Parameter values for the second intersection point.
*
*
* OUTPUT     :  jstat   - status messages
*                                = 1   : Coincidence of curves
*                                = 0   : No coincidence.
*                                < 0   : Error.
*
*
* METHOD     : March along one curve, and for each step iterate to
*              the closest point of the other curve at the midpoint and
*              the endpoint of the step. The geometry and knot vectors of
*              both curves are considered when making the step, and we
*              march along the curve that has set the step.
*
* CALLS      : s1221  - Evaluate B-spline curve.
*              s1307  - Compute unit tangent and radius of curvature.
*              s1311  - Find current step length.
*              sh1992  - Find box-size of object.
*              s6lenght - Length of vector.
*
*
* REFERENCES :
*
* WRITTEN BY : Tor Dokken, SI, Oslo, Norway. July 1989
* REWISED BY : Vibeke Skytt, SI, Oslo, Norway. Oct. 1990.
*
*********************************************************************
*/
{
  int kstat;          /* Status variable                                 */
  int ki;             /* Counter.                                        */
  int kleftc1=0;      /* Left indicator for point calculation of curve 1.*/
  int kleftc2=0;      /* Left indicator for point calculation of curve 2.*/
  int kk1,kk2,kn1,kn2;/* Orders and number of vertices of curves         */
  int kdim;           /* The dimension of the space in which the curves lie. */
  int kpos=0;         /* Position of error                               */
  int kderc=2;        /* Number of derivatives to be claculated on the curves */
  int kdum;           /* Temporary variable                              */
  int kchange;        /* Indicates which curve that is marched along.
			 = 0 : First curve.
			 = 1 : Second curve.                             */
  int kknot;          /* Indicates if the next knot in the marching direction
			 is before or after the current knot.            */
  double s3dinf1[20]; /* Pointer to storage for point info of curve 1
			  (10 dobules pr point when idim=3, 7 when idim=3) */
  double s3dinf2[20]; /* Pointer to storage for point info of curve 2
			  (10 dobules pr point when idim=3, 7 when idim=3) */
  double *st1;        /* Knot vector of first curve                      */
  double *st2;        /* Knot vector of second curve                     */
  double tfirst1,tfirst2;/* First parameter value on curves              */
  double tend1,tend2; /* Last parameter on curves                        */
  double sderc1[20];  /* Position, first and second derivatives on curve 1 */
  double sderc2[20];  /* Position, first and second derivatives on curve 2 */
  double tx,tx1,tx2;  /* Parameter values of first curve.  */
  double ty,ty1,ty2;  /* Parameter value of second curve.  */
  double tminstep;    /* Referance value in parameter domain     */
  double tstep;       /* Final step length     */
  double txstep,tystep;  /* Step length     */
  double txmaxinc,tymaxinc;  /* Maximal increment in parameter value along curve*/
  double txlengthend,tylengthend;  /* Length of 1st derivative at start of segment */
  double txincre,tyincre;      /* Parameter value increment */
  double txmax,tymax;        /* Local maximal step length                       */
  double tdist;       /* Distance */
  double tpos;        /* New iteration  point on curve pc2     */

 /* Pointer to curve evaluator routine of 2. curve.  */

  fevalcProc fevalc;
/*
 #if defined(SISLNEEDPROTOTYPES)
   void (*fevalc)(SISLCurve *, int, double , int *, double [], int *);
 #else
      void (*fevalc)();
 #endif
 */
     /* UJK, aug 93, make min step in parameter domain based on the
	max parameter values */
     tminstep  = max(fabs(pc1->et[pc1->ik-1]),fabs(pc1->et[pc1->in]));
     tminstep += max(fabs(pc2->et[pc2->ik-1]),fabs(pc2->et[pc2->in]));
     tminstep *= REL_PAR_RES;


     /* Make maximal step length based on box-size of curve 1 */

  sh1992cu(pc1,0,aepsge,&kstat);
  if (kstat < 0) goto error;

  txmax = MAX(pc1->pbox->e2max[0][0] - pc1->pbox->e2min[0][0],
	     pc1->pbox->e2max[0][1] - pc1->pbox->e2min[0][1]);
  txmax = MAX(txmax,pc1->pbox->e2max[0][2] - pc1->pbox->e2min[0][2]);

  /* Make maximal step length based on box-size of curve 2 */

  sh1992cu(pc2,0,aepsge,&kstat);
  if (kstat < 0) goto error;

  tymax = MAX(pc2->pbox->e2max[0][0] - pc2->pbox->e2min[0][0],
	     pc2->pbox->e2max[0][1] - pc2->pbox->e2min[0][1]);
  tymax = MAX(tymax,pc2->pbox->e2max[0][2] - pc2->pbox->e2min[0][2]);

  /* Copy curve pc1 attributes to local parameters.  */

  kdim = pc1 -> idim;
  kk1    = pc1 -> ik;
  kn1    = pc1 -> in;
  st1    = pc1 -> et;

  /* Copy curve pc2 attributes to local parameters.  */

  kk2    = pc2 -> ik;
  kn2    = pc2 -> in;
  st2    = pc2 -> et;

  /* Check that dimensions are equal */

  if (kdim != pc2->idim || kdim > 3) goto err105;

  /* Copy interval description into local variables */

  if ( epar1[0]<epar2[0] )
    {
      tfirst1 = epar1[0];
      tfirst2 = epar1[1];
      tend1   = epar2[0];
      tend2   = epar2[1];
    }
  else
    {
      tfirst1 = epar2[0];
      tfirst2 = epar2[1];
      tend1   = epar1[0];
      tend2   = epar1[1];
    }

  /* To make sure we do not start outside or end outside the curve we
     truncate tstart1 and tend1 to the knot interval of the curve */

  tfirst1 = MAX(tfirst1,st1[kk1-1]);
  tend1   = MIN(tend1,st1[kn1]);

  /* To make sure we do not start outside or end outside the curve we
     truncate tstart2 and tend2 to the knot interval of the curve */

  if (tfirst2 <= tend2)
  {
     tfirst2 = MAX(tfirst2,st2[kk2-1]);
     tend2   = MIN(tend2,st2[kn2]);
     kknot = 1;
  }
  else
  {
     tfirst2 = MIN(tfirst2,st2[kn2]);
     tend2 = MAX(tend2,st2[kk2-1]);
     kknot = -1;
  }

  /* Set curve evaluator of 2. curve.  */

  fevalc = (kknot == 1) ? s1221 : s1227;

  /* Store knot values at start of curve */

  tx1 = tfirst1;
  kdum = MAX(kk1,kk2);
  txmaxinc = (tend1-tfirst1)/(kdum*kdum);

  /* Make start point and intital step length based on first curve  */

  s1221(pc1,kderc,tx1,&kleftc1,sderc1,&kstat);
  if (kstat<0) goto error;

  ty1 = tfirst2;
  tymaxinc = fabs(tend2-tfirst2)/(kdum*kdum);

  /* Make start point and intital step length based on second curve  */

fevalc(pc2,kderc,ty1,&kleftc2,sderc2,&kstat);
  if (kstat<0) goto error;

  /* While end not reached */


  while (tx1 < tend1 && kknot*ty1 < kknot*tend2)
    {

      /* Calculate unit tangent and radius of curvature of first curve. */

      s1307(sderc1,kdim,s3dinf1,&kstat);
      if (kstat<0) goto error;

      /* Calculate step length based on curvature of first curve. */

      txstep = s1311(s3dinf1[3*kdim],aepsge,tymax,&kstat);
      if (kstat<0) goto error;

      /* Remember length of start tangent, end of zero segment */

      txlengthend = s6length(sderc1+kdim,kdim,&kstat);
      if (kstat<0) goto error;

      /* Calculate unit tangent and radius of curvature of second curve. */

      s1307(sderc2,kdim,s3dinf2,&kstat);
      if (kstat<0) goto error;

      /* Calculate step length based on curvature */

      tystep = s1311(s3dinf2[3*kdim],aepsge,txmax,&kstat);
      if (kstat<0) goto error;

      /* Remember length of start tangent, end of zero segment */

      tylengthend = s6length(sderc2+kdim,kdim,&kstat);
      if (kstat<0) goto error;

      /*  Find minimum step length.  */

      tstep = MIN(txstep,tystep);
      kchange = (txstep <= tystep) ? 0 : 1;

      /*  Find candidate end point, make sure that no breaks in tangent or
	  curvature exists between start and endpoints of the segment      */
      /* Compute increment in the parameter values.  Use tminstep if the
         tangent has zero length.  */

      if (DEQUAL(txlengthend,DZERO))
	  txincre = tminstep;
      else
        txincre = MIN(tstep/txlengthend,txmaxinc);

      if (DEQUAL(tylengthend,DZERO))
	tyincre = tminstep;
      else
        tyincre = MIN(tstep/tylengthend,tymaxinc);

      /*  Make sure that we don't pass any knots of curve 1. */

      if (tx1 + txincre > st1[kleftc1+1] + tminstep &&
	  tx1 < st1[kleftc1+1] - tminstep)
	{
	  txincre = st1[kleftc1+1] - tx1;
	  tstep = txincre*txlengthend;
	  tyincre = (tylengthend > DZERO) ? tstep/tylengthend : tminstep;
	  kchange = 0;
	}

       /* Avoid passing second next knot of curve 2. */

      if (kknot*(ty1 + tyincre) > kknot*(st2[kleftc2+kknot]+tminstep) &&
	  kknot*ty1 > kknot*(st2[kleftc2+kknot]-tminstep))
	{
	  tyincre = kknot*(st2[kleftc2+kknot] - ty1);
	  tstep = tyincre*tylengthend;
	  txincre = (txlengthend > DZERO) ? tstep/txlengthend : tminstep;
	  kchange = 1;
	}

       /* Avoid passing next knot of curve 2. */

      if (kknot < 0 && (ty1 - tyincre < st2[kleftc2] - tminstep) &&
	  (ty1 < st2[kleftc2] + tminstep))
	{
	  tyincre = kknot*(st2[kleftc2+kknot] - ty1);
	  tstep = tyincre*tylengthend;
	  txincre = (txlengthend > DZERO) ? tstep/txlengthend : tminstep;
	  kchange = 1;
	}


      /* Set endpoints of step.  */

      tx2 = tx1 + txincre;
      ty2 = ty1 + kknot*tyincre;

      for (tx=(tx1+tx2)/(double)2.0, ty=(ty1+ty2)/(double)2.0, ki=0;
       ki<2; ki++, tx=tx2, ty=ty2)
      {
	 if (kchange == 0)
	 {
	    if (tx >= tend1) break;

	    /* March along first curve. Iterate down to the second.  */

	    s1786_s9relax(s1221,fevalc,pc1,pc2,kderc,aepsge,tx,&kleftc1,sderc1,ty,
			  &tpos,&kleftc2,sderc2,jstat);
	    if (kstat < 0) goto error;
	 }
	 else
	 {
	    /* UJK, 05.05.91     if (kknot*tx >= kknot*tend2) break; */
	    if (kknot*ty >= kknot*tend2) break;

	    /* March along second curve. Iterate down to the first.  */
	    s1786_s9relax(fevalc,s1221,pc2,pc1,kderc,aepsge,ty,&kleftc2,sderc2,tx,
			  &tpos,&kleftc1,sderc1,jstat);
	    if (kstat < 0) goto error;
	 }

	  /*  Check if point on curve and surface are within positional and
	      angular tolerances */

	  tdist = s6dist(sderc1,sderc2,kdim);

	  if (tdist>aepsge)
	    {
	      /*      Points not within tolerances, curve and surface do not
		      coincide */
	      goto war00;
	    }
	}

      /*   Update start parameter value of segment, and calculate right
	   hand derivative */

      if (kchange == 0)
      {
	 tx1 = tx2;
	 ty1 = tpos;
      }
      else
      {
	 tx1 = tpos;
	 ty1 = ty2;
      }
    }

  /*  Curves within tolerance */

  /*  Curves within tolerance. Test if the start- and endpoint of any
     of the curves are equal.   */

  *jstat = (DEQUAL(tfirst1,tend1) || DEQUAL(tfirst2,tend2)) ? 0 : 1;
  goto out;

/* Curve and surface not within tolerance */
war00: *jstat = 0;
goto out;

/* Error in input, dimension not equal to 2 or 3 */

err105: *jstat = -105;
        s6err("S1786",*jstat,kpos);
        goto out;

/* Error in lower level function */

error:  *jstat = kstat;
        s6err("S1786",*jstat,kpos);
        goto out;

out:
 return;
}


#if defined(SISLNEEDPROTOTYPES)

static void
   s1786_s9relax(fevalcProc fevalc1,fevalcProc fevalc2,
		 SISLCurve *pc1,SISLCurve *pc2,
		 int ider,double aepsge,double ax1,int *jleft1,double eder1[],
		 double anext,double *cx2,int *jleft2,double eder2[],int *jstat)
#else
static void s1786_s9relax(fevalc1,fevalc2,pc1,pc2,ider,aepsge,ax1,jleft1,eder1,anext,
		    cx2,jleft2,eder2,jstat)
    fevalcProc 	fevalc1;
    fevalcProc 	fevalc2;
    SISLCurve 	*pc1;
    SISLCurve 	*pc2;
    int 	ider;
    double 	aepsge;
    double 	ax1;
    int 	*jleft1;
    double 	eder1[];
    double 	anext;
    double 	*cx2;
    int 	*jleft2;
    double 	eder2[];
    int 	*jstat;
#endif
/*
*********************************************************************
*
*********************************************************************
*
* PURPOSE    : Iterate the first curve in a given parameter value and
*              iterate down to the closest point on the second curve
*              to the position on the first curve.
*
*
* INPUT      : fevalc1 - Curve evaluator corresponding to first curve.
*              fevalc1 - Curve evaluator corresponding to second curve.
*              pc1     - Pointer to the first curve.
*              pc2     - Pointer to the second curve.
*              ider    - Number of derivatives to compute. 0 <= ider <= 2.
*              aepsge  - Geometry resolution.
*              ax1     - Parameter value at which to evaluate curve 1.
*              anext   - Start parameter to the iteration on curve 2.
*
*
* INPUT/OUTPUT : jleft1  - Parameter used to set knot interval of curve1.
*                          Used in s1221.
*                jleft2  - Parameter used to set knot interval of curve2.
*
*
* OUTPUT     : eder1   - 0-ider'th derivative of curve 1 evaluated in ax1.
*                        Dimension is (ider+1)*pc1->idim.
*              cx2     - Parameter value of the point on curve 2 closest
*                        to the point given by eder1.
*              eder2   - 0-ider'th derivative of curve 2 evaluated in *cx2.
*                        Dimension is (ider+1)*pc2->idim.
*              jstat   - status messages
*                                > 0   : Warning.
*                                = 0   : Ok.
*                                < 0   : Error.
*
*
* METHOD     :
*
*
* CALLS      :  s1221     - Evaluate curve.
*               s1771     - Closest point between a curve and a point.
*               newPoint  - Create new point object.
*               freePoint - Free point object.
*
*
* REFERENCES :
*
* WRITTEN BY : Vibeke Skytt, SI, Oslo, Norway. Oct. 1990
*
*********************************************************************
*/
{
   int kstat = 0;         /* Status variable.  */
   double tstart;         /* Start parameter value of curve 2.  */
   double tend;           /* End parameter value of curve 2.    */
   SISLPoint *qpoint = SISL_NULL;  /* SISLPoint instance used to represent point on curve 1. */

   /* Find endpoints of the parameter interval of curve 2.  */

   tstart = *(pc2->et + pc2->ik - 1);
   tend = *(pc2->et + pc2->in);


   /*  Make point sderc at curve at ax1 */

   fevalc1(pc1,ider,ax1,jleft1,eder1,&kstat);

   if (kstat<0) goto error;

   /* Find closest point on curve 2 to eder1 */

   qpoint = newPoint(eder1,pc1->idim,0);
   if (qpoint==SISL_NULL) goto err101;

   s1771(qpoint,pc2,aepsge,tstart,tend,anext,cx2,&kstat);
   if(kstat<0) goto error;

   /* Calculate point and derivatives in second curve */

   fevalc2(pc2,ider,*cx2,jleft2,eder2,&kstat);

   if (kstat<0) goto error;

   *jstat = 0;
   goto out;

   /* Error in space allocation.  */

   err101 :
      *jstat = -101;
   goto out;

   /* Error in lower level routine.  */

   error :
      *jstat = kstat;
   goto out;

   out :
     if (qpoint != SISL_NULL) freePoint(qpoint);

      return;
}
