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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-

// Copyright 2010 Michael Smith, all rights reserved.

//      This library is free software; you can redistribute it and / or
//      modify it under the terms of the GNU Lesser General Public
//      License as published by the Free Software Foundation; either
//      version 2.1 of the License, or (at your option) any later version.

// Derived closely from:
/****************************************
 * 2D Vector Classes
 * By Bill Perone (billperone@yahoo.com)
 * Original: 9-16-2002
 * Revised: 19-11-2003
 *          18-12-2003
 *          06-06-2004
 *
 * © 2003, This code is provided "as is" and you can use it freely as long as
 * credit is given to Bill Perone in the application it is used in
 ****************************************/

#ifndef VECTOR2_H
#define VECTOR2_H

#include <math.h>

template <typename T>
struct Vector2
{
        T x, y;

        // trivial ctor
        Vector2<T>() {memset(this, 0, sizeof(*this));}

        // setting ctor
        Vector2<T>(const T x0, const T y0): x(x0), y(y0) {}

        // function call operator
        void operator ()(const T x0, const T y0)
        {       x= x0; y= y0;   }

        // test for equality
        bool operator==(const Vector2<T> &v)
        {       return (x==v.x && y==v.y);      }

        // test for inequality
        bool operator!=(const Vector2<T> &v)
        {       return (x!=v.x || y!=v.y);      }

        // negation
        Vector2<T> operator -(void) const
        {       return Vector2<T>(-x, -y);      }

        // addition
        Vector2<T> operator +(const Vector2<T> &v) const
        {       return Vector2<T>(x+v.x, y+v.y);        }

        // subtraction
        Vector2<T> operator -(const Vector2<T> &v) const
        {   return Vector2<T>(x-v.x, y-v.y);    }

        // uniform scaling
        Vector2<T> operator *(const T num) const
        {
                Vector2<T> temp(*this);
                return temp*=num;
        }

        // uniform scaling
        Vector2<T> operator /(const T num) const
        {
                Vector2<T> temp(*this);
                return temp/=num;
        }

        // addition
        Vector2<T> &operator +=(const Vector2<T> &v)
        {
                x+=v.x; y+=v.y;
                return *this;
        }

        // subtraction
        Vector2<T> &operator -=(const Vector2<T> &v)
        {
                x-=v.x; y-=v.y;
                return *this;
        }

        // uniform scaling
        Vector2<T> &operator *=(const T num)
        {
                x*=num; y*=num;
                return *this;
        }

        // uniform scaling
        Vector2<T> &operator /=(const T num)
        {
                x/=num; y/=num;
                return *this;
        }

        // dot product
        T operator *(const Vector2<T> &v) const
        {       return x*v.x + y*v.y;   }

        // gets the length of this vector squared
        T length_squared() const
        {       return (T)(*this * *this);   }

        // gets the length of this vector
        T length() const
        {       return (T)sqrt(*this * *this);   }

        // normalizes this vector
        void normalize()
        {       *this/=length();        }

        // returns the normalized vector
        Vector2<T> normalized() const
        {   return  *this/length();  }

        // reflects this vector about n
        void reflect(const Vector2<T> &n)
        {
                Vector2<T> orig(*this);
                project(n);
                *this= *this*2 - orig;
        }

        // projects this vector onto v
        void project(const Vector2<T> &v)
        {       *this= v * (*this * v)/(v*v);   }

        // returns this vector projected onto v
        Vector2<T> projected(const Vector2<T> &v)
        {   return v * (*this * v)/(v*v);       }

        // computes the angle between 2 arbitrary vectors
        T angle(const Vector2<T> &v1, const Vector2<T> &v2)
        {   return (T)acosf((v1*v2) / (v1.length()*v2.length()));  }

        // computes the angle between 2 normalized arbitrary vectors
        T angle_normalized(const Vector2<T> &v1, const Vector2<T> &v2)
        {   return (T)acosf(v1*v2);  }

};

typedef Vector2<int>                    Vector2i;
typedef Vector2<unsigned int>   Vector2ui;
typedef Vector2<long>                   Vector2l;
typedef Vector2<unsigned long>  Vector2ul;
typedef Vector2<float>                  Vector2f;

#endif // VECTOR2_H