Plane.cpp

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/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 Source Code 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.

Doom 3 Source Code 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 Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/

#include "../precompiled.h"
#pragma hdrstop

idPlane plane_origin( 0.0f, 0.0f, 0.0f, 0.0f );

/*
================
idPlane::Type
================
*/
int idPlane::Type( void ) const {
        if ( Normal()[0] == 0.0f ) {
                if ( Normal()[1] == 0.0f ) {
                        return Normal()[2] > 0.0f ? PLANETYPE_Z : PLANETYPE_NEGZ;
                }
                else if ( Normal()[2] == 0.0f ) {
                        return Normal()[1] > 0.0f ? PLANETYPE_Y : PLANETYPE_NEGY;
                }
                else {
                        return PLANETYPE_ZEROX;
                }
        }
        else if ( Normal()[1] == 0.0f ) {
                if ( Normal()[2] == 0.0f ) {
                        return Normal()[0] > 0.0f ? PLANETYPE_X : PLANETYPE_NEGX;
                }
                else {
                        return PLANETYPE_ZEROY;
                }
        }
        else if ( Normal()[2] == 0.0f ) {
                return PLANETYPE_ZEROZ;
        }
        else {
                return PLANETYPE_NONAXIAL;
        }
}

/*
================
idPlane::HeightFit
================
*/
bool idPlane::HeightFit( const idVec3 *points, const int numPoints ) {
        int i;
        float sumXX = 0.0f, sumXY = 0.0f, sumXZ = 0.0f;
        float sumYY = 0.0f, sumYZ = 0.0f;
        idVec3 sum, average, dir;

        if ( numPoints == 1 ) {
                a = 0.0f;
                b = 0.0f;
                c = 1.0f;
                d = -points[0].z;
                return true;
        }
        if ( numPoints == 2 ) {
                dir = points[1] - points[0];
                Normal() = dir.Cross( idVec3( 0, 0, 1 ) ).Cross( dir );
                Normalize();
                d = -( Normal() * points[0] );
                return true;
        }

        sum.Zero();
        for ( i = 0; i < numPoints; i++) {
                sum += points[i];
        }
        average = sum / numPoints;

        for ( i = 0; i < numPoints; i++ ) {
                dir = points[i] - average;
                sumXX += dir.x * dir.x;
                sumXY += dir.x * dir.y;
                sumXZ += dir.x * dir.z;
                sumYY += dir.y * dir.y;
                sumYZ += dir.y * dir.z;
        }

        idMat2 m( sumXX, sumXY, sumXY, sumYY );
        if ( !m.InverseSelf() ) {
                return false;
        }

        a = - sumXZ * m[0][0] - sumYZ * m[0][1];
        b = - sumXZ * m[1][0] - sumYZ * m[1][1];
        c = 1.0f;
        Normalize();
        d = -( a * average.x + b * average.y + c * average.z );
        return true;
}

/*
================
idPlane::PlaneIntersection
================
*/
bool idPlane::PlaneIntersection( const idPlane &plane, idVec3 &start, idVec3 &dir ) const {
        double n00, n01, n11, det, invDet, f0, f1;

        n00 = Normal().LengthSqr();
        n01 = Normal() * plane.Normal();
        n11 = plane.Normal().LengthSqr();
        det = n00 * n11 - n01 * n01;

        if ( idMath::Fabs(det) < 1e-6f ) {
                return false;
        }

        invDet = 1.0f / det;
        f0 = ( n01 * plane.d - n11 * d ) * invDet;
        f1 = ( n01 * d - n00 * plane.d ) * invDet;

        dir = Normal().Cross( plane.Normal() );
        start = f0 * Normal() + f1 * plane.Normal();
        return true;
}

/*
=============
idPlane::ToString
=============
*/
const char *idPlane::ToString( int precision ) const {
        return idStr::FloatArrayToString( ToFloatPtr(), GetDimension(), precision );
}