vector.c

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/*                        V E C T O R . C
 * BRL-CAD
 *
 * Copyright (c) 2004-2006 United States Government as represented by
 * the U.S. Army Research Laboratory.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this file; see the file named COPYING for more
 * information.
 */

/** \addtogroup plot */
/*@{*/
/** @file vector.c
 *
 *  @author
 *      Michael John Muuss
 *
 *  @par Source
 *      SECAD/VLD Computing Consortium, Bldg 394
 *@n    The U. S. Army Ballistic Research Laboratory
 *@n    Aberdeen Proving Ground, Maryland  21005-5066
 *
 */


#ifndef lint
static const char RCSid[] = "@(#)$Header: /cvsroot/brlcad/brlcad/src/libbn/vector.c,v 14.11 2006/09/07 01:19:17 lbutler Exp $ (BRL)";
#endif

#include "common.h"



#include <stdio.h>
#include <math.h>

#include "machine.h"
#include "vmath.h"
#include "plot3.h"
#include "bu.h"
#include "bn.h"

/**
 *                      T P _ 3 V E C T O R
 *@brief
 *  Draw a vector between points "from" and "to", with the option
 *  of having an arrowhead on either or both ends.
 *
 *  The fromheadfract and toheadfract values indicate the length
 *  of the arrowheads relative to the length of the vector to-from.
 *  A typical value is 0.1, making the head 10% of the size of the vector.
 *  The sign of the "fract" values indicates the pointing direction.
 *  Positive points towards the "to" point, negative points towards "from".
 *  Upon return, the virtual pen is left at the "to" position.
 */
void
tp_3vector(FILE *plotfp, fastf_t *from, fastf_t *to, double fromheadfract, double toheadfract)
{
        register fastf_t        len;
        register fastf_t        hooklen;
        vect_t  diff;
        vect_t  c1, c2;
        vect_t  h1, h2;
        vect_t  backup;
        point_t tip;

        pdv_3line( plotfp, from, to );
        /* "pen" is left at "to" position */

        VSUB2( diff, to, from );
        if( (len = MAGNITUDE(diff)) < SMALL )  return;
        VSCALE( diff, diff, 1/len );
        bn_vec_ortho( c1, diff );
        VCROSS( c2, c1, diff );

        if( fromheadfract != 0 )  {
                hooklen = fromheadfract*len;
                VSCALE( backup, diff, -hooklen );

                VSCALE( h1, c1, hooklen );
                VADD3( tip, from, h1, backup );
                pdv_3move( plotfp, from );
                pdv_3cont( plotfp, tip );

                VSCALE( h2, c2, hooklen );
                VADD3( tip, from, h2, backup );
                pdv_3move( plotfp, tip );
        }
        if( toheadfract != 0 )  {
                hooklen = toheadfract*len;
                VSCALE( backup, diff, -hooklen );

                VSCALE( h1, c1, hooklen );
                VADD3( tip, to, h1, backup );
                pdv_3move( plotfp, to );
                pdv_3cont( plotfp, tip );

                VSCALE( h2, c2, hooklen );
                VADD3( tip, to, h2, backup );
                pdv_3move( plotfp, tip );
        }
        /* Be certain "pen" is left at "to" position */
        if( fromheadfract != 0 || toheadfract != 0 )
                pdv_3cont( plotfp, to );

}

void
PL_FORTRAN(f3vect, F3VECT)(fp, fx, fy, fz, tx, ty, tz, fl, tl )
FILE    **fp;
float   *fx;
float   *fy;
float   *fz;
float   *tx;
float   *ty;
float   *tz;
float   *fl;
float   *tl;
{
        point_t from, to;

        VSET( from, *fx, *fy, *fz );
        VSET( to, *tx, *ty, *tz );
        tp_3vector( *fp, from, to, *fl, *tl );
}

/*@}*/
/*
 * Local Variables:
 * mode: C
 * tab-width: 8
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 * ex: shiftwidth=4 tabstop=8
 */

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