vmap/libs/math/plane.h

/*
   Copyright (C) 2001-2006, William Joseph.
   All Rights Reserved.

   This file is part of GtkRadiant.

   GtkRadiant 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 2 of the License, or
   (at your option) any later version.

   GtkRadiant 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 GtkRadiant; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#if !defined( INCLUDED_MATH_PLANE_H )
#define INCLUDED_MATH_PLANE_H

/// \file
/// \brief Plane data types and related operations.

#include "math/matrix.h"

/// \brief A plane equation stored in double-precision floating-point.
class Plane3
{
public:
double a, b, c, d;

Plane3(){
}
Plane3( double _a, double _b, double _c, double _d )
	: a( _a ), b( _b ), c( _c ), d( _d ){
}
template<typename Element>
Plane3( const BasicVector3<Element>& normal, double dist )
	: a( normal.x() ), b( normal.y() ), c( normal.z() ), d( dist ){
}

BasicVector3<double>& normal(){
	return reinterpret_cast<BasicVector3<double>&>( *this );
}
const BasicVector3<double>& normal() const {
	return reinterpret_cast<const BasicVector3<double>&>( *this );
}
double& dist(){
	return d;
}
const double& dist() const {
	return d;
}
};

inline Plane3 plane3_normalised( const Plane3& plane ){
	double rmagnitude = 1.0 / sqrt( plane.a * plane.a + plane.b * plane.b + plane.c * plane.c );
	return Plane3(
			   plane.a * rmagnitude,
			   plane.b * rmagnitude,
			   plane.c * rmagnitude,
			   plane.d * rmagnitude
			   );
}

inline Plane3 plane3_translated( const Plane3& plane, const Vector3& translation ){
	Plane3 transformed;
	transformed.a = plane.a;
	transformed.b = plane.b;
	transformed.c = plane.c;
	transformed.d = -( ( -plane.d * transformed.a + translation.x() ) * transformed.a +
					   ( -plane.d * transformed.b + translation.y() ) * transformed.b +
					   ( -plane.d * transformed.c + translation.z() ) * transformed.c );
	return transformed;
}

inline Plane3 plane3_transformed( const Plane3& plane, const Matrix4& transform ){
	Plane3 transformed;
	transformed.a = transform[0] * plane.a + transform[4] * plane.b + transform[8] * plane.c;
	transformed.b = transform[1] * plane.a + transform[5] * plane.b + transform[9] * plane.c;
	transformed.c = transform[2] * plane.a + transform[6] * plane.b + transform[10] * plane.c;
	transformed.d = -( ( -plane.d * transformed.a + transform[12] ) * transformed.a +
					   ( -plane.d * transformed.b + transform[13] ) * transformed.b +
					   ( -plane.d * transformed.c + transform[14] ) * transformed.c );
	return transformed;
}

inline Plane3 plane3_inverse_transformed( const Plane3& plane, const Matrix4& transform ){
	return Plane3
		   (
			   transform[ 0] * plane.a + transform[ 1] * plane.b + transform[ 2] * plane.c + transform[ 3] * plane.d,
			   transform[ 4] * plane.a + transform[ 5] * plane.b + transform[ 6] * plane.c + transform[ 7] * plane.d,
			   transform[ 8] * plane.a + transform[ 9] * plane.b + transform[10] * plane.c + transform[11] * plane.d,
			   transform[12] * plane.a + transform[13] * plane.b + transform[14] * plane.c + transform[15] * plane.d
		   );
}

inline Plane3 plane3_flipped( const Plane3& plane ){
	return Plane3( vector3_negated( plane.normal() ), -plane.dist() );
}

const double c_PLANE_NORMAL_EPSILON = 0.0001f;
const double c_PLANE_DIST_EPSILON = 0.02;

inline bool plane3_equal( const Plane3& self, const Plane3& other ){
	return vector3_equal_epsilon( self.normal(), other.normal(), c_PLANE_NORMAL_EPSILON )
		   && float_equal_epsilon( self.dist(), other.dist(), c_PLANE_DIST_EPSILON );
}

inline bool plane3_opposing( const Plane3& self, const Plane3& other ){
	return plane3_equal( self, plane3_flipped( other ) );
}

inline bool plane3_valid( const Plane3& self ){
	return float_equal_epsilon( vector3_dot( self.normal(), self.normal() ), 1.0, 0.01 );
}

template<typename Element>
inline Plane3 plane3_for_points( const BasicVector3<Element>& p0, const BasicVector3<Element>& p1, const BasicVector3<Element>& p2 ){
	Plane3 self;
	self.normal() = vector3_normalised( vector3_cross( vector3_subtracted( p1, p0 ), vector3_subtracted( p2, p0 ) ) );
	self.dist() = vector3_dot( p0, self.normal() );
	return self;
}

template<typename Element>
inline Plane3 plane3_for_points( const BasicVector3<Element> planepts[3] ){
	return plane3_for_points( planepts[2], planepts[1], planepts[0] );
}


#endif