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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: s6curvrad.c,v 1.2 2001-03-19 15:59:01 afr Exp $
*
*/
#define S6CURVRAD
#include "sislP.h"
#if defined(SISLNEEDPROTOTYPES)
void
s6curvrad(double epnt1[],double epnt2[],double etang[],int idim,
double *crad,int *jstat)
#else
void s6curvrad(epnt1,epnt2,etang,idim,crad,jstat)
int idim,*jstat;
double epnt1[],epnt2[],etang[],*crad;
#endif
/*
*********************************************************************
*
* PURPOSE : Given both endpoints of a curve segment and the tangent in
* one of the endpoints, estimate the curvature radius of the
* curve segment in the endpoint where the tangent is given.
*
*
* INPUT : epnt1 - First endpoint.
* epnt2 - Second endpoint.
* etang - Given tangent.
* idim - Dimension of geometry space.
*
*
* OUTPUT : crad - Estimated curvature radius.
* jstat - status messages
* = 1 : Tangent vector zero.
* = 0 : ok
* < 0 : error
*
*
* METHOD : Pass a circle through the points having the given tangent
* in the given endpoint. Compute the radius of this circle.
*
* REFERENCES :
*
* USE :
*
*-
* CALLS : s6dist - Distance between two points.
* s6diff - Difference vector between two vectors.
*
* WRITTEN BY : Vibeke Skytt, SI, 05.90.
*
*********************************************************************
*/
{
int kstat = 0; /* Status variable. */
double tdist; /* Distance between the endpoints. */
double tdot; /* Scalar product between tangent and vector
between endpoints. */
double tlmid; /* Length of tangent vector. */
double tcos; /* Cosinus to the angle between the tangent
and the vector between the endpoints. */
double tang; /* Angle at the centre of the circle
between the vectors from origo to
the given endpoints. */
double tdum; /* Denominator in expression to find
the radius of the circle. */
double trad; /* The curvature radius, i.e. the radius
of the circle. */
double sdiff[3]; /* Difference vector between the endpoints. */
/* Test input. */
if (idim != 3) goto err104;
/* Estimate curvature radius based on endpoints and tangent. */
tdist = s6dist(epnt1,epnt2,idim);
s6diff(epnt2,epnt1,idim,sdiff);
tdot = s6scpr(etang,sdiff,idim);
tlmid = s6length(etang,idim,&kstat);
tcos = (tlmid*tdist != DZERO) ? fabs(tdot/(tlmid*tdist)) : fabs(tdot);
tcos = MIN((double)1.0,tcos);
tang = 2*acos(tcos);
tdum = sqrt(2-2*cos(tang));
trad = (tdum > REL_COMP_RES) ? tdist/tdum : -1.0;
/* Set curvature radius. */
*crad = trad;
*jstat = 0;
goto out;
/* Error in input. */
err104 :
*jstat = -104;
goto out;
out :
return;
}
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