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/*
* Copyright (C) 1998, 2000-2007, 2010, 2011, 2012, 2013 SINTEF ICT,
* Applied Mathematics, Norway.
*
* Contact information: E-mail: tor.dokken@sintef.no
* SINTEF ICT, Department of Applied Mathematics,
* P.O. Box 124 Blindern,
* 0314 Oslo, Norway.
*
* This file is part of SISL.
*
* SISL is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* SISL 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with SISL. If not, see
* <http://www.gnu.org/licenses/>.
*
* In accordance with Section 7(b) of the GNU Affero General Public
* License, a covered work must retain the producer line in every data
* file that is created or manipulated using SISL.
*
* Other Usage
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the SISL library without
* disclosing the source code of your own applications.
*
* This file may be used in accordance with the terms contained in a
* written agreement between you and SINTEF ICT.
*/
#include "sisl-copyright.h"
/*
*
* $Id: crvlintang.c,v 1.1 1994-04-21 12:10:42 boh Exp $
*
*/
#define CRV_LIN_TANG
#include "sislP.h"
#if defined(SISLNEEDPROTOTYPES)
void
crv_lin_tang(SISLCurve *pc1, double point[], double normal[],
double ang_tol, double guess_par, double *iter_par,
int *jstat)
#else
void crv_lin_tang(pc1, point, normal, ang_tol, guess_par,
iter_par, jstat)
SISLCurve *pc1;
double point[];
double normal[];
double ang_tol;
double guess_par;
double *iter_par;
int *jstat;
#endif
/*
*********************************************************************
*
*********************************************************************
*
* PURPOSE : Newton iteration to find a tangent between the curve
* pc1 and a line.
*
*
* INPUT : pc1 - Pointer to the first curve.
* point - Original point on the line.
* normal - Normal to the line.
* ang_tol - Angular tolerance (in radians).
* guess_par - Guess parameter values in pc1.
*
*
*
* OUTPUT : iter_par - Tangential parameter values in pc1.
* jstat - status messages
* < 0 : error.
*
*
* METHOD : Use po_crv_tang.c to find the tangent from point to pc1,
* and check the tangent direction against normal.
* Guess_par and iter_par must not be separated by a tangential
* discontinuity.
*
*
* REFERENCES :
*
*
* WRITTEN BY : Johannes Kaasa, SI, March 1992.
*
*********************************************************************
*/
{
int kstat = 0; /* Local status variable. */
int kpos = 0; /* Position of error. */
int kder = 0; /* Evaluates only position. */
int kleft = 0; /* Knot interval pointer. */
double iter_pnt[2]; /* Resulting point on the curve. */
double diffvec[2]; /* Vector between point and curve. */
double tangent[2]; /* Tangent along the line. */
int kdim = 2; /* 2 dimensional. */
double iter_ang; /* Angular deviation. */
/* Test input. */
if (pc1->idim != 2) goto err106;
/* Find the tangent from point to pc1. */
po_crv_tang(pc1, point, ang_tol, guess_par, iter_par, &kstat);
if (kstat < 0) goto error;
/* Check the result. */
s1221(pc1, kder, *iter_par, &kleft, iter_pnt, &kstat);
if (kstat < 0) goto error;
diffvec[0] = iter_pnt[0] - point[0];
diffvec[1] = iter_pnt[1] - point[1];
tangent[0] = -normal[1];
tangent[1] = normal[0];
iter_ang = s6ang(diffvec, tangent, kdim);
if (iter_ang < ang_tol)
*jstat = 1;
else
*jstat = 2;
goto out;
/* Error in input. Conflicting dimensions. */
err106: *jstat = -106;
s6err("crv_lin_tang",*jstat,kpos);
goto out;
/* Error in lower level routine. */
error : *jstat = kstat;
s6err("crv_lin_tang",*jstat,kpos);
goto out;
out: return;
}
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