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# Unity conversion between radians and degrees

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Hello, Community! I just had an idea on how to make radian/degree conversion easier in my engine. What if I encapsulated each in a class that automatically makes the conversion. However, in a previous post, the concept of making a class based off of intrisic was doomed to failure. ex:
class Radian
{
Real mRad;

public:
explicit Radian ( Real r=0 ) : mRad(r) {}
Radian ( const Degree& d );
const Radian& operator = ( const Real& f ) { mRad = f; return *this; }
const Radian& operator = ( const Radian& r ) { mRad = r.mRad; return *this; }
const Radian& operator = ( const Degree& d );

Real GetDegrees() const; // see bottom of this file
Real GetRadians() const { return mRad; }
Real GetAngleUnits() const;

Radian operator + ( const Radian& r ) const { return Radian ( mRad + r.mRad ); }
Radian operator + ( const Degree& d ) const;
Radian& operator += ( const Radian& r ) { mRad += r.mRad; return *this; }
Radian& operator += ( const Degree& d );
Radian operator - () { return Radian(-mRad); }
Radian operator - ( const Radian& r ) const { return Radian ( mRad - r.mRad ); }
Radian operator - ( const Degree& d ) const;
Radian& operator -= ( const Radian& r ) { mRad -= r.mRad; return *this; }
Radian& operator -= ( const Degree& d );
Radian operator * ( Real f ) const { return Radian ( mRad * f ); }
Radian operator * ( const Radian& f ) const { return Radian ( mRad * f.mRad ); }
Radian& operator *= ( Real f ) { mRad *= f; return *this; }
Radian operator / ( Real f ) const { return Radian ( mRad / f ); }
Radian& operator /= ( Real f ) { mRad /= f; return *this; }

bool operator <  ( const Radian& r ) const { return mRad <  r.mRad; }
bool operator <= ( const Radian& r ) const { return mRad <= r.mRad; }
bool operator == ( const Radian& r ) const { return mRad == r.mRad; }
bool operator != ( const Radian& r ) const { return mRad != r.mRad; }
bool operator >= ( const Radian& r ) const { return mRad >= r.mRad; }
bool operator >  ( const Radian& r ) const { return mRad >  r.mRad; }
};


Where 'Real' can be typedef'd to float or double; PS. This is from the OGRE engine [smile] I'm just curious to see if it sounds like a good idea, exorcist_bob

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Why not just make the interface to all your engine's methods take radians, rather than an arbitrary combination of different angular units? Then you don't need a separate class at all.

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The reason for it is for extensibilities sake, so that if someone else builds a module that returns degrees, I can easily convert it over.

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You don't need full blown classes for that. Just have a rad_2_deg() and deg_2_rad() function and you're set.

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Quote:
 Original post by exorcist_bobThe reason for it is for extensibilities sake, so that if someone else builds a module that returns degrees, I can easily convert it over.

YAGNI ?

What's wrong with:
namespace {  const float pi = 3.14159f;    inline float degToRad(float rad)  {    return rad * 180.0f / pi;  }  inline float radToDeg(float deg)  {    return deg * pi / 180.0f;  }}

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or even:

#define DEGTORAD 0.0174532925199432957f
#define RADTODEG 57.295779513082320876f

I see. Thanks!

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Quote:
 Original post by exorcist_bobThe reason for it is for extensibilities sake, so that if someone else builds a module that returns degrees, I can easily convert it over.

As the engine's interface designer, you get to specify what is reasonable and what is not. My opinion is that if you already support radians, you need not support degrees, and vice versa. That is, it is not unreasonable to declare "my interface shall only take radians, and your modules must comply accordingly".

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