Question

I’m giving option to compile the program with either float or double type, but there is a problem: I need to manually set either GL_FLOAT or GL_DOUBLE, because I dont know how can I do the following:

typedef float MYTYPE;

#if MYTYPE == float
    #define GL_MYTYPE GL_FLOAT // used for vertex array parameters.
#else
    #define GL_MYTYPE GL_DOUBLE
#endif

Note: I dont have C++11 or whatsoever, just the good old C++.

Answer 1

You can do it this way:

#define MYFLOAT

#ifdef MYFLOAT
    typedef float MYTYPE;
     #define GL_MYTYPE GL_FLOAT // used for vertex array parameters.
#else
    typedef double MYTYPE;
    #define GL_MYTYPE GL_DOUBLE
#endif

You would need to define MYFLOAT if you want to use float, or omit it to use double.

PS: keep in ind this is not evaluated at compile time, but at pre-processing time.