//
// vector3d.cc
//
// A vector in 3d space
//
// Copyright (C) J. Belson	1998.11.30
//

#include <cmath>

#include "vector3d.h"


using namespace std;


/**
 * Constructor
 */
vector3d::vector3d(float ii, float jj, float kk, bool norm)
{
	i = ii;
	j = jj;
	k = kk;

	if (norm) {
		normalise();
	}
}


/**
 * Calculate A.B
 * Divide result by |A| and |B| to get cos(angle)
 */
float vector3d::dot_product(const vector3d &v) const
{
	return i*v.i + j*v.j + k*v.k;
}


/**
 * Calculate A+B
 */
vector3d vector3d::vector_product(const vector3d &v) const
{
	vector3d tmp(	j*v.k - k*v.j,
					k*v.i - i*v.k,
					i*v.j - j*v.i);
	return tmp;
}


/**
 * Get angle between two vectors
 */
float vector3d::angle(const vector3d& v) const
{
	const float dp = dot_product(v);

	if (dp > 1.0) {
		return 0;
	}
	if (dp < -1.0) {
		return M_PI;
	}

	return acos(dp);
}


/**
 * Calculate magnitude of this vector
 */
float vector3d::magnitude(void) const
{
	return sqrt(i*i + j*j + k*k);	
}


/**
 * Normalise by dividing each component
 *  by vector magnitude
 */
void vector3d::normalise(void)
{
	float mag = magnitude();
	if (mag) {
		i /= mag;
		j /= mag;
		k /= mag;
	}
}


/**
 * Add another vector to this one
 */
vector3d vector3d::operator+(vector3d v) const
{
	vector3d temp(v.i + i, v.j + j, v.k + k);

	return temp;
}


/**
 * Subtract another vector from this one
 */
vector3d vector3d::operator-(vector3d v) const
{
	vector3d temp(i - v.i, j - v.j, k - v.k);

	return temp;
}


/**
 * Scale this vector by a constant
 */
vector3d vector3d::operator*(float f) const
{
	vector3d temp(i*f, j*f, k*f);

	return temp;
}


/**
 * Negate this vector
 */
vector3d vector3d::operator-() const
{
	vector3d temp(-i, -j, -k);
	
	return temp;
}


/**
 * Write vector attributes to a stream
 * @param str Stream to write to
 * @param v	Vector to operate on
 */
ostream& operator<<(ostream& str, const vector3d& v)
{
	str << "[" << v.i << ", " << v.j << ", " << v.k << "]";

	return str;
}