Sun1602/Utility/polar.h

#ifndef N_POLAR_H
#define N_POLAR_H
//------------------------------------------------------------------------------
/**
    A polar coordinate inline class, consisting of 2 angles theta (latitude)
    and rho (longitude). Also offers conversion between cartesian and 
    polar space.

    Allowed range for theta is 0..180 degree (in rad!) and for rho 0..360 degree
    (in rad).

    @author
    - RadonLabs GmbH 
    @since
    - 2005.7.06
    @remarks
    - Áö¿Ï Ãß°¡ 
*/

#include <stdlib.h>
#include <math.h>
#include <float.h>
#include "vector.h"

//------------------------------------------------------------------------------
class polar2
{
public:
    /// the default constructor
    polar2();
    /// constructor, theta and rho args
    polar2(float t, float r);
    /// constructor, normalized cartesian vector as arg
    polar2(const vector3& v);
    /// the copy constructor
    polar2(const polar2& src);
    /// the assignment operator
    polar2& operator=(const polar2& rhs);
    /// convert to normalized cartesian coords 
    vector3 get_cartesian() const;
    /// get theta and rho in a 2d vec
    vector2 get() const;
    /// set to polar object
    void set(const polar2& p);
    /// set to theta and rho
    void set(const float t, const float r);
    /// set to cartesian 
    void set(const vector3&);
    /// fuzzy equality check 
    bool isequal(const polar2& rhs, float tol);

    float theta;
    float rho;

private:
    /// the equal operator is not allowed, use isequal() with tolerance!
    bool operator==(const polar2& /*rhs*/) { return false; }
};

//------------------------------------------------------------------------------
/**
*/
inline
polar2::polar2() :
    theta(0.0f),
    rho(0.0f)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
inline
polar2::polar2(float t, float r) :
    theta(t),
    rho(r)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
inline
polar2::polar2(const vector3& v)
{
    this->set(v);
}

//------------------------------------------------------------------------------
/**
*/
inline
polar2::polar2(const polar2& src) :
    theta(src.theta),
    rho(src.rho)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
inline
polar2&
polar2::operator=(const polar2& rhs)
{
    this->theta = rhs.theta;
    this->rho = rhs.rho;
    return *this;
}

//------------------------------------------------------------------------------
/**
*/
inline
void
polar2::set(const polar2& p)
{
    this->theta = p.theta;
    this->rho = p.rho;
}

//------------------------------------------------------------------------------
/**
*/
inline
void
polar2::set(const float t, const float r)
{
    this->theta = t;
    this->rho = r;
}

//------------------------------------------------------------------------------
/**
    Convert cartesian to polar.
*/
inline
void
polar2::set(const vector3& vec)
{
    double dTheta = acos(vec.y);

    // build a normalized 2d vector of the xz component
    vector2 v2(vec.x, vec.z);
    v2.norm();

    // adjust dRho based on the quadrant we are in
    double dRho;
    if ((v2.x >= 0.0f) && (v2.y >= 0.0f))
    {
        // quadrant 1
        dRho = acos(v2.x);
    }
    else if ((v2.x < 0.0f) && (v2.y >= 0.0f))
    {
        // quadrant 2 
        dRho = acos(v2.y) + n_deg2rad(90.0f);
    }
    else if ((v2.x < 0.0f) && (v2.y < 0.0f))
    {
        // quadrant 3
        dRho = acos(-v2.x) + n_deg2rad(180.0f);
    }
    else
    {
        // quadrant 4
        dRho = acos(-v2.y) + n_deg2rad(270.0f);
    }

    this->theta = (float) dTheta;
    this->rho   = (float) dRho;
}
    
//------------------------------------------------------------------------------
/**
    Convert polar to cartesian.
*/
inline
vector3
polar2::get_cartesian() const
{
    vector3 v;
    double sin_theta = sin(this->theta);
    double cos_theta = cos(this->theta);
    double sin_rho   = sin(this->rho);
    double cos_rho   = cos(this->rho);
    float x = (float) (sin_theta * sin_rho);
    float y = (float) cos_theta;
    float z = (float) (sin_theta * cos_rho);
    v.set(x,y,z);
    return v;
}

//------------------------------------------------------------------------------
/**
*/
inline
bool
polar2::isequal(const polar2& rhs, float tol)
{
    float dt = n_abs(rhs.theta - this->theta);
    float dr = n_abs(rhs.rho - this->rho);
    if (dt > tol)      return false;
    else if (dr > tol) return false;
    return true;
}

//------------------------------------------------------------------------------
#endif