//
// vector2d.h
//
// A vector in 2d space
//
// Copyright (C) J. Belson	2000.12.16
//


#include <cmath>

#include "vector2d.h"

using namespace std;

/**
 * Constructor
 */
vector2d::vector2d(float i, float j)
{
	this->i = i;
	this->j = j;
}

///
/// Calculate A.B
/// Divide result by |A| and |B| to get cos(angle)
///
float vector2d::dot_product(vector2d &v)
{
	return i*v.i + j*v.j;
}


#if 0
vector2d vector2d::vector_product(vector2d &v)
{
	vector3d tmp(	j*v.k - k*v.j,
					k*v.i - i*v.k,
					i*v.j - j*v.i);
	return tmp;
}
#endif

/// Calculate magnitude of this vector
float vector2d::magnitude(void)
{
	return sqrt(i*i + j*j);	
}


///
/// Normalise by dividing each component
///  by vector magnitude
///
void vector2d::normalise(void)
{
	float mag = magnitude();
	if (mag) {
		i /= mag;
		j /= mag;
	}
}


///
/// Rotate this vector clockwise
/// Should be doing this with matrices but hey.
///
void vector2d::rotate(float radians)
{
	float new_i =  i*cos(radians) + j*sin(radians);
	float new_j = -i*sin(radians) + j*cos(radians);

	i = new_i;
	j = new_j;
}



//
// Operators
//
/// Add another vector to this one
vector2d vector2d::operator+(vector2d v)
{
	vector2d temp(v.i + i, v.j + j);

	return temp;
}

/// Scale this vector by a constant
vector2d vector2d::operator*(float f)
{
	vector2d temp(i * f, j * f);

	return temp;
}

/// Write vector attributes to a stream
/// @param str	stream to write to
/// @param v	vector to operate on
ostream& operator<<(ostream& str, vector2d& v)
{
	str << "[" << v.i << ", " << v.j << "]";

	return str;
}