/*
 * Copyright 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <math.h>
#include "JNIHelper.h"

namespace ndk_helper
{

/******************************************************************
 * Helper class for vector math operations
 * Currently all implementations are in pure C++.
 * Each class is an opaque class so caller does not have a direct access
 * to each element. This is for an ease of future optimization to use vector operations.
 *
 */

class Vec2;
class Vec3;
class Vec4;
class Mat4;

/******************************************************************
 * 2 elements vector class
 *
 */
class Vec2
{
private:
    float x_;
    float y_;

public:
    friend class Vec3;
    friend class Vec4;
    friend class Mat4;
    friend class Quaternion;

    Vec2()
    {
        x_ = y_ = 0.f;
    }

    Vec2( const float fX, const float fY )
    {
        x_ = fX;
        y_ = fY;
    }

    Vec2( const Vec2& vec )
    {
        x_ = vec.x_;
        y_ = vec.y_;
    }

    Vec2( const float* pVec )
    {
        x_ = (*pVec++);
        y_ = (*pVec++);
    }

    //Operators
    Vec2 operator*( const Vec2& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ * rhs.x_;
        ret.y_ = y_ * rhs.y_;
        return ret;
    }

    Vec2 operator/( const Vec2& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ / rhs.x_;
        ret.y_ = y_ / rhs.y_;
        return ret;
    }

    Vec2 operator+( const Vec2& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ + rhs.x_;
        ret.y_ = y_ + rhs.y_;
        return ret;
    }

    Vec2 operator-( const Vec2& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ - rhs.x_;
        ret.y_ = y_ - rhs.y_;
        return ret;
    }

    Vec2& operator+=( const Vec2& rhs )
    {
        x_ += rhs.x_;
        y_ += rhs.y_;
        return *this;
    }

    Vec2& operator-=( const Vec2& rhs )
    {
        x_ -= rhs.x_;
        y_ -= rhs.y_;
        return *this;
    }

    Vec2& operator*=( const Vec2& rhs )
    {
        x_ *= rhs.x_;
        y_ *= rhs.y_;
        return *this;
    }

    Vec2& operator/=( const Vec2& rhs )
    {
        x_ /= rhs.x_;
        y_ /= rhs.y_;
        return *this;
    }

    //External operators
    friend Vec2 operator-( const Vec2& rhs )
    {
        return Vec2( rhs ) *= -1;
    }

    friend Vec2 operator*( const float lhs, const Vec2& rhs )
    {
        Vec2 ret;
        ret.x_ = lhs * rhs.x_;
        ret.y_ = lhs * rhs.y_;
        return ret;
    }

    friend Vec2 operator/( const float lhs, const Vec2& rhs )
    {
        Vec2 ret;
        ret.x_ = lhs / rhs.x_;
        ret.y_ = lhs / rhs.y_;
        return ret;
    }

    //Operators with float
    Vec2 operator*( const float& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ * rhs;
        ret.y_ = y_ * rhs;
        return ret;
    }

    Vec2& operator*=( const float& rhs )
    {
        x_ = x_ * rhs;
        y_ = y_ * rhs;
        return *this;
    }

    Vec2 operator/( const float& rhs ) const
    {
        Vec2 ret;
        ret.x_ = x_ / rhs;
        ret.y_ = y_ / rhs;
        return ret;
    }

    Vec2& operator/=( const float& rhs )
    {
        x_ = x_ / rhs;
        y_ = y_ / rhs;
        return *this;
    }

    //Compare
    bool operator==( const Vec2& rhs ) const
    {
        if( x_ != rhs.x_ || y_ != rhs.y_ )
            return false;
        return true;
    }

    bool operator!=( const Vec2& rhs ) const
    {
        if( x_ == rhs.x_ )
            return false;

        return true;
    }

    float Length() const
    {
        return sqrtf( x_ * x_ + y_ * y_ );
    }

    Vec2 Normalize()
    {
        float len = Length();
        x_ = x_ / len;
        y_ = y_ / len;
        return *this;
    }

    float Dot( const Vec2& rhs )
    {
        return x_ * rhs.x_ + y_ * rhs.y_;
    }

    bool Validate()
    {
        if( isnan( x_ ) || isnan( y_ ) )
            return false;
        return true;
    }

    void Value( float& fX, float& fY )
    {
        fX = x_;
        fY = y_;
    }

    void Dump()
    {
        LOGI( "Vec2 %f %f", x_, y_ );
    }
};

/******************************************************************
 * 3 elements vector class
 *
 */
class Vec3
{
private:
    float x_, y_, z_;

public:
    friend class Vec4;
    friend class Mat4;
    friend class Quaternion;

    Vec3()
    {
        x_ = y_ = z_ = 0.f;
    }

    Vec3( const float fX, const float fY, const float fZ )
    {
        x_ = fX;
        y_ = fY;
        z_ = fZ;
    }

    Vec3( const Vec3& vec )
    {
        x_ = vec.x_;
        y_ = vec.y_;
        z_ = vec.z_;
    }

    Vec3( const float* pVec )
    {
        x_ = (*pVec++);
        y_ = (*pVec++);
        z_ = *pVec;
    }

    Vec3( const Vec2& vec, float f )
    {
        x_ = vec.x_;
        y_ = vec.y_;
        z_ = f;
    }

    Vec3( const Vec4& vec );

    //Operators
    Vec3 operator*( const Vec3& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ * rhs.x_;
        ret.y_ = y_ * rhs.y_;
        ret.z_ = z_ * rhs.z_;
        return ret;
    }

    Vec3 operator/( const Vec3& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ / rhs.x_;
        ret.y_ = y_ / rhs.y_;
        ret.z_ = z_ / rhs.z_;
        return ret;
    }

    Vec3 operator+( const Vec3& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ + rhs.x_;
        ret.y_ = y_ + rhs.y_;
        ret.z_ = z_ + rhs.z_;
        return ret;
    }

    Vec3 operator-( const Vec3& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ - rhs.x_;
        ret.y_ = y_ - rhs.y_;
        ret.z_ = z_ - rhs.z_;
        return ret;
    }

    Vec3& operator+=( const Vec3& rhs )
    {
        x_ += rhs.x_;
        y_ += rhs.y_;
        z_ += rhs.z_;
        return *this;
    }

    Vec3& operator-=( const Vec3& rhs )
    {
        x_ -= rhs.x_;
        y_ -= rhs.y_;
        z_ -= rhs.z_;
        return *this;
    }

    Vec3& operator*=( const Vec3& rhs )
    {
        x_ *= rhs.x_;
        y_ *= rhs.y_;
        z_ *= rhs.z_;
        return *this;
    }

    Vec3& operator/=( const Vec3& rhs )
    {
        x_ /= rhs.x_;
        y_ /= rhs.y_;
        z_ /= rhs.z_;
        return *this;
    }

    //External operators
    friend Vec3 operator-( const Vec3& rhs )
    {
        return Vec3( rhs ) *= -1;
    }

    friend Vec3 operator*( const float lhs, const Vec3& rhs )
    {
        Vec3 ret;
        ret.x_ = lhs * rhs.x_;
        ret.y_ = lhs * rhs.y_;
        ret.z_ = lhs * rhs.z_;
        return ret;
    }

    friend Vec3 operator/( const float lhs, const Vec3& rhs )
    {
        Vec3 ret;
        ret.x_ = lhs / rhs.x_;
        ret.y_ = lhs / rhs.y_;
        ret.z_ = lhs / rhs.z_;
        return ret;
    }

    //Operators with float
    Vec3 operator*( const float& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ * rhs;
        ret.y_ = y_ * rhs;
        ret.z_ = z_ * rhs;
        return ret;
    }

    Vec3& operator*=( const float& rhs )
    {
        x_ = x_ * rhs;
        y_ = y_ * rhs;
        z_ = z_ * rhs;
        return *this;
    }

    Vec3 operator/( const float& rhs ) const
    {
        Vec3 ret;
        ret.x_ = x_ / rhs;
        ret.y_ = y_ / rhs;
        ret.z_ = z_ / rhs;
        return ret;
    }

    Vec3& operator/=( const float& rhs )
    {
        x_ = x_ / rhs;
        y_ = y_ / rhs;
        z_ = z_ / rhs;
        return *this;
    }

    //Compare
    bool operator==( const Vec3& rhs ) const
    {
        if( x_ != rhs.x_ || y_ != rhs.y_ || z_ != rhs.z_ )
            return false;
        return true;
    }

    bool operator!=( const Vec3& rhs ) const
    {
        if( x_ == rhs.x_ )
            return false;

        return true;
    }

    float Length() const
    {
        return sqrtf( x_ * x_ + y_ * y_ + z_ * z_ );
    }

    Vec3 Normalize()
    {
        float len = Length();
        x_ = x_ / len;
        y_ = y_ / len;
        z_ = z_ / len;
        return *this;
    }

    float Dot( const Vec3& rhs )
    {
        return x_ * rhs.x_ + y_ * rhs.y_ + z_ * rhs.z_;
    }

    Vec3 Cross( const Vec3& rhs )
    {
        Vec3 ret;
        ret.x_ = y_ * rhs.z_ - z_ * rhs.y_;
        ret.y_ = z_ * rhs.x_ - x_ * rhs.z_;
        ret.z_ = x_ * rhs.y_ - y_ * rhs.x_;
        return ret;
    }

    bool Validate()
    {
        if( isnan( x_ ) || isnan( y_ ) || isnan( z_ ) )
            return false;
        return true;
    }

    void Value( float& fX, float& fY, float& fZ )
    {
        fX = x_;
        fY = y_;
        fZ = z_;
    }

    void Dump()
    {
        LOGI( "Vec3 %f %f %f", x_, y_, z_ );
    }
};

/******************************************************************
 * 4 elements vector class
 *
 */
class Vec4
{
private:
    float x_, y_, z_, w_;

public:
    friend class Vec3;
    friend class Mat4;
    friend class Quaternion;

    Vec4()
    {
        x_ = y_ = z_ = w_ = 0.f;
    }

    Vec4( const float fX, const float fY, const float fZ, const float fW )
    {
        x_ = fX;
        y_ = fY;
        z_ = fZ;
        w_ = fW;
    }

    Vec4( const Vec4& vec )
    {
        x_ = vec.x_;
        y_ = vec.y_;
        z_ = vec.z_;
        w_ = vec.w_;
    }

    Vec4( const Vec3& vec, const float fW )
    {
        x_ = vec.x_;
        y_ = vec.y_;
        z_ = vec.z_;
        w_ = fW;
    }

    Vec4( const float* pVec )
    {
        x_ = (*pVec++);
        y_ = (*pVec++);
        z_ = *pVec;
        w_ = *pVec;
    }

    //Operators
    Vec4 operator*( const Vec4& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ * rhs.x_;
        ret.y_ = y_ * rhs.y_;
        ret.z_ = z_ * rhs.z_;
        ret.w_ = z_ * rhs.w_;
        return ret;
    }

    Vec4 operator/( const Vec4& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ / rhs.x_;
        ret.y_ = y_ / rhs.y_;
        ret.z_ = z_ / rhs.z_;
        ret.w_ = z_ / rhs.w_;
        return ret;
    }

    Vec4 operator+( const Vec4& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ + rhs.x_;
        ret.y_ = y_ + rhs.y_;
        ret.z_ = z_ + rhs.z_;
        ret.w_ = z_ + rhs.w_;
        return ret;
    }

    Vec4 operator-( const Vec4& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ - rhs.x_;
        ret.y_ = y_ - rhs.y_;
        ret.z_ = z_ - rhs.z_;
        ret.w_ = z_ - rhs.w_;
        return ret;
    }

    Vec4& operator+=( const Vec4& rhs )
    {
        x_ += rhs.x_;
        y_ += rhs.y_;
        z_ += rhs.z_;
        w_ += rhs.w_;
        return *this;
    }

    Vec4& operator-=( const Vec4& rhs )
    {
        x_ -= rhs.x_;
        y_ -= rhs.y_;
        z_ -= rhs.z_;
        w_ -= rhs.w_;
        return *this;
    }

    Vec4& operator*=( const Vec4& rhs )
    {
        x_ *= rhs.x_;
        y_ *= rhs.y_;
        z_ *= rhs.z_;
        w_ *= rhs.w_;
        return *this;
    }

    Vec4& operator/=( const Vec4& rhs )
    {
        x_ /= rhs.x_;
        y_ /= rhs.y_;
        z_ /= rhs.z_;
        w_ /= rhs.w_;
        return *this;
    }

    //External operators
    friend Vec4 operator-( const Vec4& rhs )
    {
        return Vec4( rhs ) *= -1;
    }

    friend Vec4 operator*( const float lhs, const Vec4& rhs )
    {
        Vec4 ret;
        ret.x_ = lhs * rhs.x_;
        ret.y_ = lhs * rhs.y_;
        ret.z_ = lhs * rhs.z_;
        ret.w_ = lhs * rhs.w_;
        return ret;
    }

    friend Vec4 operator/( const float lhs, const Vec4& rhs )
    {
        Vec4 ret;
        ret.x_ = lhs / rhs.x_;
        ret.y_ = lhs / rhs.y_;
        ret.z_ = lhs / rhs.z_;
        ret.w_ = lhs / rhs.w_;
        return ret;
    }

    //Operators with float
    Vec4 operator*( const float& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ * rhs;
        ret.y_ = y_ * rhs;
        ret.z_ = z_ * rhs;
        ret.w_ = w_ * rhs;
        return ret;
    }

    Vec4& operator*=( const float& rhs )
    {
        x_ = x_ * rhs;
        y_ = y_ * rhs;
        z_ = z_ * rhs;
        w_ = w_ * rhs;
        return *this;
    }

    Vec4 operator/( const float& rhs ) const
    {
        Vec4 ret;
        ret.x_ = x_ / rhs;
        ret.y_ = y_ / rhs;
        ret.z_ = z_ / rhs;
        ret.w_ = w_ / rhs;
        return ret;
    }

    Vec4& operator/=( const float& rhs )
    {
        x_ = x_ / rhs;
        y_ = y_ / rhs;
        z_ = z_ / rhs;
        w_ = w_ / rhs;
        return *this;
    }

    //Compare
    bool operator==( const Vec4& rhs ) const
    {
        if( x_ != rhs.x_ || y_ != rhs.y_ || z_ != rhs.z_ || w_ != rhs.w_ )
            return false;
        return true;
    }

    bool operator!=( const Vec4& rhs ) const
    {
        if( x_ == rhs.x_ )
            return false;

        return true;
    }

    Vec4 operator*( const Mat4& rhs ) const;

    float Length() const
    {
        return sqrtf( x_ * x_ + y_ * y_ + z_ * z_ + w_ * w_ );
    }

    Vec4 Normalize()
    {
        float len = Length();
        x_ = x_ / len;
        y_ = y_ / len;
        z_ = z_ / len;
        w_ = w_ / len;
        return *this;
    }

    float Dot( const Vec3& rhs )
    {
        return x_ * rhs.x_ + y_ * rhs.y_ + z_ * rhs.z_;
    }

    Vec3 Cross( const Vec3& rhs )
    {
        Vec3 ret;
        ret.x_ = y_ * rhs.z_ - z_ * rhs.y_;
        ret.y_ = z_ * rhs.x_ - x_ * rhs.z_;
        ret.z_ = x_ * rhs.y_ - y_ * rhs.x_;
        return ret;
    }

    bool Validate()
    {
        if( isnan( x_ ) || isnan( y_ ) || isnan( z_ ) || isnan( w_ ) )
            return false;
        return true;
    }

    void Value( float& fX, float& fY, float& fZ, float& fW )
    {
        fX = x_;
        fY = y_;
        fZ = z_;
        fW = w_;
    }
};

/******************************************************************
 * 4x4 matrix
 *
 */
class Mat4
{
private:
    float f_[16];

public:
    friend class Vec3;
    friend class Vec4;
    friend class Quaternion;

    Mat4();
    Mat4( const float* );

    Mat4 operator*( const Mat4& rhs ) const;
    Vec4 operator*( const Vec4& rhs ) const;

    Mat4 operator+( const Mat4& rhs ) const
    {
        Mat4 ret;
        for( int32_t i = 0; i < 16; ++i )
        {
            ret.f_[i] = f_[i] + rhs.f_[i];
        }
        return ret;
    }

    Mat4 operator-( const Mat4& rhs ) const
    {
        Mat4 ret;
        for( int32_t i = 0; i < 16; ++i )
        {
            ret.f_[i] = f_[i] - rhs.f_[i];
        }
        return ret;
    }

    Mat4& operator+=( const Mat4& rhs )
    {
        for( int32_t i = 0; i < 16; ++i )
        {
            f_[i] += rhs.f_[i];
        }
        return *this;
    }

    Mat4& operator-=( const Mat4& rhs )
    {
        for( int32_t i = 0; i < 16; ++i )
        {
            f_[i] -= rhs.f_[i];
        }
        return *this;
    }

    Mat4& operator*=( const Mat4& rhs )
    {
        Mat4 ret;
        ret.f_[0] = f_[0] * rhs.f_[0] + f_[4] * rhs.f_[1] + f_[8] * rhs.f_[2]
                + f_[12] * rhs.f_[3];
        ret.f_[1] = f_[1] * rhs.f_[0] + f_[5] * rhs.f_[1] + f_[9] * rhs.f_[2]
                + f_[13] * rhs.f_[3];
        ret.f_[2] = f_[2] * rhs.f_[0] + f_[6] * rhs.f_[1] + f_[10] * rhs.f_[2]
                + f_[14] * rhs.f_[3];
        ret.f_[3] = f_[3] * rhs.f_[0] + f_[7] * rhs.f_[1] + f_[11] * rhs.f_[2]
                + f_[15] * rhs.f_[3];

        ret.f_[4] = f_[0] * rhs.f_[4] + f_[4] * rhs.f_[5] + f_[8] * rhs.f_[6]
                + f_[12] * rhs.f_[7];
        ret.f_[5] = f_[1] * rhs.f_[4] + f_[5] * rhs.f_[5] + f_[9] * rhs.f_[6]
                + f_[13] * rhs.f_[7];
        ret.f_[6] = f_[2] * rhs.f_[4] + f_[6] * rhs.f_[5] + f_[10] * rhs.f_[6]
                + f_[14] * rhs.f_[7];
        ret.f_[7] = f_[3] * rhs.f_[4] + f_[7] * rhs.f_[5] + f_[11] * rhs.f_[6]
                + f_[15] * rhs.f_[7];

        ret.f_[8] = f_[0] * rhs.f_[8] + f_[4] * rhs.f_[9] + f_[8] * rhs.f_[10]
                + f_[12] * rhs.f_[11];
        ret.f_[9] = f_[1] * rhs.f_[8] + f_[5] * rhs.f_[9] + f_[9] * rhs.f_[10]
                + f_[13] * rhs.f_[11];
        ret.f_[10] = f_[2] * rhs.f_[8] + f_[6] * rhs.f_[9] + f_[10] * rhs.f_[10]
                + f_[14] * rhs.f_[11];
        ret.f_[11] = f_[3] * rhs.f_[8] + f_[7] * rhs.f_[9] + f_[11] * rhs.f_[10]
                + f_[15] * rhs.f_[11];

        ret.f_[12] = f_[0] * rhs.f_[12] + f_[4] * rhs.f_[13] + f_[8] * rhs.f_[14]
                + f_[12] * rhs.f_[15];
        ret.f_[13] = f_[1] * rhs.f_[12] + f_[5] * rhs.f_[13] + f_[9] * rhs.f_[14]
                + f_[13] * rhs.f_[15];
        ret.f_[14] = f_[2] * rhs.f_[12] + f_[6] * rhs.f_[13] + f_[10] * rhs.f_[14]
                + f_[14] * rhs.f_[15];
        ret.f_[15] = f_[3] * rhs.f_[12] + f_[7] * rhs.f_[13] + f_[11] * rhs.f_[14]
                + f_[15] * rhs.f_[15];

        *this = ret;
        return *this;
    }

    Mat4 operator*( const float rhs )
    {
        Mat4 ret;
        for( int32_t i = 0; i < 16; ++i )
        {
            ret.f_[i] = f_[i] * rhs;
        }
        return ret;
    }

    Mat4& operator*=( const float rhs )
    {
        for( int32_t i = 0; i < 16; ++i )
        {
            f_[i] *= rhs;
        }
        return *this;
    }

    Mat4& operator=( const Mat4& rhs )
    {
        for( int32_t i = 0; i < 16; ++i )
        {
            f_[i] = rhs.f_[i];
        }
        return *this;
    }

    Mat4 Inverse();

    Mat4 Transpose()
    {
        Mat4 ret;
        ret.f_[0] = f_[0];
        ret.f_[1] = f_[4];
        ret.f_[2] = f_[8];
        ret.f_[3] = f_[12];
        ret.f_[4] = f_[1];
        ret.f_[5] = f_[5];
        ret.f_[6] = f_[9];
        ret.f_[7] = f_[13];
        ret.f_[8] = f_[2];
        ret.f_[9] = f_[6];
        ret.f_[10] = f_[10];
        ret.f_[11] = f_[14];
        ret.f_[12] = f_[3];
        ret.f_[13] = f_[7];
        ret.f_[14] = f_[11];
        ret.f_[15] = f_[15];
        *this = ret;
        return *this;
    }

    Mat4& PostTranslate( float tx, float ty, float tz )
    {
        f_[12] += (tx * f_[0]) + (ty * f_[4]) + (tz * f_[8]);
        f_[13] += (tx * f_[1]) + (ty * f_[5]) + (tz * f_[9]);
        f_[14] += (tx * f_[2]) + (ty * f_[6]) + (tz * f_[10]);
        f_[15] += (tx * f_[3]) + (ty * f_[7]) + (tz * f_[11]);
        return *this;
    }

    float* Ptr()
    {
        return f_;
    }

    //--------------------------------------------------------------------------------
    // Misc
    //--------------------------------------------------------------------------------
    static Mat4 Perspective( float width, float height, float nearPlane, float farPlane );

    static Mat4 LookAt( const Vec3& vEye, const Vec3& vAt, const Vec3& vUp );

    static Mat4 Translation( const float fX, const float fY, const float fZ );
    static Mat4 Translation( const Vec3 vec );

    static Mat4 RotationX( const float angle );

    static Mat4 RotationY( const float angle );

    static Mat4 RotationZ( const float angle );

    static Mat4 Identity()
    {
        Mat4 ret;
        ret.f_[0] = 1.f;
        ret.f_[1] = 0;
        ret.f_[2] = 0;
        ret.f_[3] = 0;
        ret.f_[4] = 0;
        ret.f_[5] = 1.f;
        ret.f_[6] = 0;
        ret.f_[7] = 0;
        ret.f_[8] = 0;
        ret.f_[9] = 0;
        ret.f_[10] = 1.f;
        ret.f_[11] = 0;
        ret.f_[12] = 0;
        ret.f_[13] = 0;
        ret.f_[14] = 0;
        ret.f_[15] = 1.f;
        return ret;
    }

    void Dump()
    {
        LOGI( "%f %f %f %f", f_[0], f_[1], f_[2], f_[3] );
        LOGI( "%f %f %f %f", f_[4], f_[5], f_[6], f_[7] );
        LOGI( "%f %f %f %f", f_[8], f_[9], f_[10], f_[11] );
        LOGI( "%f %f %f %f", f_[12], f_[13], f_[14], f_[15] );
    }
};

/******************************************************************
 * Quaternion class
 *
 */
class Quaternion
{
private:
    float x_, y_, z_, w_;

public:
    friend class Vec3;
    friend class Vec4;
    friend class Mat4;

    Quaternion()
    {
        x_ = 0.f;
        y_ = 0.f;
        z_ = 0.f;
        w_ = 1.f;
    }

    Quaternion( const float fX, const float fY, const float fZ, const float fW )
    {
        x_ = fX;
        y_ = fY;
        z_ = fZ;
        w_ = fW;
    }

    Quaternion( const Vec3 vec, const float fW )
    {
        x_ = vec.x_;
        y_ = vec.y_;
        z_ = vec.z_;
        w_ = fW;
    }

    Quaternion( const float* p )
    {
        x_ = *p++;
        y_ = *p++;
        z_ = *p++;
        w_ = *p++;
    }

    Quaternion operator*( const Quaternion rhs )
    {
        Quaternion ret;
        ret.x_ = x_ * rhs.w_ + y_ * rhs.z_ - z_ * rhs.y_ + w_ * rhs.x_;
        ret.y_ = -x_ * rhs.z_ + y_ * rhs.w_ + z_ * rhs.x_ + w_ * rhs.y_;
        ret.z_ = x_ * rhs.y_ - y_ * rhs.x_ + z_ * rhs.w_ + w_ * rhs.z_;
        ret.w_ = -x_ * rhs.x_ - y_ * rhs.y_ - z_ * rhs.z_ + w_ * rhs.w_;
        return ret;
    }

    Quaternion& operator*=( const Quaternion rhs )
    {
        Quaternion ret;
        ret.x_ = x_ * rhs.w_ + y_ * rhs.z_ - z_ * rhs.y_ + w_ * rhs.x_;
        ret.y_ = -x_ * rhs.z_ + y_ * rhs.w_ + z_ * rhs.x_ + w_ * rhs.y_;
        ret.z_ = x_ * rhs.y_ - y_ * rhs.x_ + z_ * rhs.w_ + w_ * rhs.z_;
        ret.w_ = -x_ * rhs.x_ - y_ * rhs.y_ - z_ * rhs.z_ + w_ * rhs.w_;
        *this = ret;
        return *this;
    }

    Quaternion Conjugate()
    {
        x_ = -x_;
        y_ = -y_;
        z_ = -z_;
        return *this;
    }

    //Non destuctive version
    Quaternion Conjugated()
    {
        Quaternion ret;
        ret.x_ = -x_;
        ret.y_ = -y_;
        ret.z_ = -z_;
        ret.w_ = w_;
        return ret;
    }

    void ToMatrix( Mat4& mat )
    {
        float x2 = x_ * x_ * 2.0f;
        float y2 = y_ * y_ * 2.0f;
        float z2 = z_ * z_ * 2.0f;
        float xy = x_ * y_ * 2.0f;
        float yz = y_ * z_ * 2.0f;
        float zx = z_ * x_ * 2.0f;
        float xw = x_ * w_ * 2.0f;
        float yw = y_ * w_ * 2.0f;
        float zw = z_ * w_ * 2.0f;

        mat.f_[0] = 1.0f - y2 - z2;
        mat.f_[1] = xy + zw;
        mat.f_[2] = zx - yw;
        mat.f_[4] = xy - zw;
        mat.f_[5] = 1.0f - z2 - x2;
        mat.f_[6] = yz + xw;
        mat.f_[8] = zx + yw;
        mat.f_[9] = yz - xw;
        mat.f_[10] = 1.0f - x2 - y2;

        mat.f_[3] = mat.f_[7] = mat.f_[11] = mat.f_[12] = mat.f_[13] = mat.f_[14] = 0.0f;
        mat.f_[15] = 1.0f;
    }

    void ToMatrixPreserveTranslate( Mat4& mat )
    {
        float x2 = x_ * x_ * 2.0f;
        float y2 = y_ * y_ * 2.0f;
        float z2 = z_ * z_ * 2.0f;
        float xy = x_ * y_ * 2.0f;
        float yz = y_ * z_ * 2.0f;
        float zx = z_ * x_ * 2.0f;
        float xw = x_ * w_ * 2.0f;
        float yw = y_ * w_ * 2.0f;
        float zw = z_ * w_ * 2.0f;

        mat.f_[0] = 1.0f - y2 - z2;
        mat.f_[1] = xy + zw;
        mat.f_[2] = zx - yw;
        mat.f_[4] = xy - zw;
        mat.f_[5] = 1.0f - z2 - x2;
        mat.f_[6] = yz + xw;
        mat.f_[8] = zx + yw;
        mat.f_[9] = yz - xw;
        mat.f_[10] = 1.0f - x2 - y2;

        mat.f_[3] = mat.f_[7] = mat.f_[11] = 0.0f;
        mat.f_[15] = 1.0f;
    }

    static Quaternion RotationAxis( const Vec3 axis, const float angle )
    {
        Quaternion ret;
        float s = sinf( angle / 2 );
        ret.x_ = s * axis.x_;
        ret.y_ = s * axis.y_;
        ret.z_ = s * axis.z_;
        ret.w_ = cosf( angle / 2 );
        return ret;
    }

    void Value( float& fX, float& fY, float& fZ, float& fW )
    {
        fX = x_;
        fY = y_;
        fZ = z_;
        fW = w_;
    }
};

} //namespace ndk_helper