/*
   Copyright (C) 1999-2006 Id Software, Inc. and contributors.
   For a list of contributors, see the accompanying CONTRIBUTORS file.

   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
 */

#ifndef __MATH_QUATERNION_H__
#define __MATH_QUATERNION_H__

#include <assert.h>
#include <math.h>

class idVec3_t;
class angles_t;
class mat3_t;

class quat_t {
public:
	float x;
	float y;
	float z;
	float w;

	quat_t();
	quat_t( float x, float y, float z, float w );
	quat_t( const quat_t & ) = default;

	friend void toQuat( idVec3_t &src, quat_t &dst );
	friend void toQuat( angles_t &src, quat_t &dst );
	friend void toQuat( mat3_t &src, quat_t &dst );

	float *vec4( void );

	float  operator[]( int index ) const;
	float &operator[]( int index );

	void set( float x, float y, float z, float w );

	quat_t &operator=( const quat_t &a ) = default;

	friend quat_t operator+( quat_t a, quat_t b );
	quat_t &operator+=( quat_t a );

	friend quat_t operator-( quat_t a, quat_t b );
	quat_t &operator-=( quat_t a );

	friend quat_t operator*( quat_t a, float b );
	friend quat_t operator*( float a, quat_t b );
	quat_t &operator*=( float a );

	friend int operator==( quat_t a, quat_t b );
	friend int operator!=( quat_t a, quat_t b );

	float Length( void );
	quat_t &Normalize( void );

	quat_t operator-();
};

inline quat_t::quat_t() {
}

inline quat_t::quat_t( float x, float y, float z, float w ) {
	this->x = x;
	this->y = y;
	this->z = z;
	this->w = w;
}

inline float *quat_t::vec4( void ) {
	return &x;
}

inline float quat_t::operator[]( int index ) const {
	assert( ( index >= 0 ) && ( index < 4 ) );
	return ( &x )[ index ];
}

inline float& quat_t::operator[]( int index ) {
	assert( ( index >= 0 ) && ( index < 4 ) );
	return ( &x )[ index ];
}

inline void quat_t::set( float x, float y, float z, float w ) {
	this->x = x;
	this->y = y;
	this->z = z;
	this->w = w;
}

inline quat_t operator+( quat_t a, quat_t b ) {
	return quat_t( a.x + b.x, a.y + b.y, a.z + b.z, a.w + b.w );
}

inline quat_t& quat_t::operator+=( quat_t a ) {
	x += a.x;
	y += a.y;
	z += a.z;
	w += a.w;

	return *this;
}

inline quat_t operator-( quat_t a, quat_t b ) {
	return quat_t( a.x - b.x, a.y - b.y, a.z - b.z, a.w - b.w );
}

inline quat_t& quat_t::operator-=( quat_t a ) {
	x -= a.x;
	y -= a.y;
	z -= a.z;
	w -= a.w;

	return *this;
}

inline quat_t operator*( quat_t a, float b ) {
	return quat_t( a.x * b, a.y * b, a.z * b, a.w * b );
}

inline quat_t operator*( float a, quat_t b ) {
	return b * a;
}

inline quat_t& quat_t::operator*=( float a ) {
	x *= a;
	y *= a;
	z *= a;
	w *= a;

	return *this;
}

inline int operator==( quat_t a, quat_t b ) {
	return ( ( a.x == b.x ) && ( a.y == b.y ) && ( a.z == b.z ) && ( a.w == b.w ) );
}

inline int operator!=( quat_t a, quat_t b ) {
	return ( ( a.x != b.x ) || ( a.y != b.y ) || (( a.z != b.z ) && ( a.w != b.w )) );
}

inline float quat_t::Length( void ) {
	float length;

	length = x * x + y * y + z * z + w * w;
	return ( float )sqrt( length );
}

inline quat_t& quat_t::Normalize( void ) {
	float length;
	float ilength;

	length = this->Length();
	if ( length ) {
		ilength = 1 / length;
		x *= ilength;
		y *= ilength;
		z *= ilength;
		w *= ilength;
	}

	return *this;
}

inline quat_t quat_t::operator-() {
	return quat_t( -x, -y, -z, -w );
}

#endif /* !__MATH_QUATERNION_H__ */
