//  $Id$
//
//  SuperTuxKart - a fun racing game with go-kart
//  Copyright (C) 2004 Steve Baker <sjbaker1@airmail.net>
//
//  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 3
//  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.

#include <plib/ssg.h>
#include "isect.hpp"

float getHeightAndNormal(ssgBranch* branch, sgVec3 my_position, sgVec3 normal)
{
    /* Look for the nearest polygon *beneath* my_position */

    ssgHit *results ;

    float hot ;        /* H.O.T == Height Of Terrain */
    sgVec3 HOTvec ;

    sgMat4 invmat ;
    sgMakeIdentMat4 ( invmat ) ;
    invmat[3][0] = - my_position [0] ;
    invmat[3][1] = - my_position [1] ;
    invmat[3][2] = 0.0 ;

    sgSetVec3 ( HOTvec, 0.0f, 0.0f, my_position [ 2 ] ) ;

    const int NUM_HITS = ssgHOT (branch, HOTvec, invmat, &results ) ;

    hot = - FLT_MAX ;

    for ( int i = 0 ; i < NUM_HITS ; i++ )
    {
        ssgHit *h = &results [ i ] ;

        float hgt = - h->plane[3] / h->plane[2] ;

        if ( hgt >= hot )
        {
            hot = hgt ;

            if ( normal != NULL )
                sgCopyVec3 ( normal, h->plane ) ;
        }
    }

    return hot ;
}