Use macro to define the type that "regular" functions use and remove `ps*` and `s*`

[felselva]

The ps* and s* functions are pretty annoying to maintain, so I was thinking of using macros to change the functions that take arrays.

Old (3 separated functions):

mfloat *vec3_add(mfloat *result, mfloat *v0, mfloat_t *v1)
{
        /* Implementation using parameter `result` */
}

struct vec3 *vec3_add(struct vec3 *result, struct vec3 *v0, struct vec3 *v1)
{
        /* Implementation using parameter `result` and call `vec3_add()` */
}

struct vec3 svec3_add(struct vec3 v0, struct vec3 v1)
{
        /* Implementation using local variable `result` and call `vec3_add()` */
}

New (1 function):

#ifdef MATHC_FUNCTION_HAS_PARAMETER_RESULT
MATHC_VEC3 vec3_add(MATHC_VEC3 result, MATHC_VEC3 v0, MATHC_VEC3 v1)
{
#else
MATHC_VEC3 vec3_add(MATHC_VEC3 v0, MATHC_VEC3 v1)
{
        struct vec3 result;
#endif
        // Implementation using the parameter `result` or local variable `result`...
        return result;
}

Then, the type of MATHC_VEC3 can be configured to be struct vec3, or struct vec3 * or mfloat_t *. If the type is struct vec3, then the first argument will be discarded from the function. Another option is to wrap the first parameter with a macro , but the implementation would still need the #ifdef to declare the local variable result if needed. Not pretty, but still prettier than many other libraries around.

PROS:

• Currently, ps* and s* functions are just abstraction and they call the functions that take arrays, which means they are essentially, but not necessarily significantly, slower.
• Faster to maintain, because there will be no need to make the ps* and s* counterparts of the functions that take arrays.

CONS:

• Internally the functions will have to be rewritten with macros. v[0] will become something like this MATHC_VEC_X(v), and the macro will do the job to turn it to vec[0] or v.x or v->x.
• Projects using ps* and s* functions will break, thus need to migrate (if they want the newer version). But, this can be quickly fixed using search & replace.
• Abuse of macros.

[heitaoflower]

Good idea!, now I just use you library to do my virtual texture repo.