Return value linearly interpolated in between to points. This function is an C++ analogue of GLSL mix function.

template<class TYPE> TYPE Mix(const TYPE x, const TYPE y, const TYPE a);
    template<class TYPE> TVec2<TYPE> Mix(const TVec2<TYPE> &x, const TVec2<TYPE> &y, const TYPE a);
    template<class TYPE> TVec3<TYPE> Mix(const TVec3<TYPE> &x, const TVec3<TYPE> &y, const TYPE a);
    template<class TYPE> TVec4<TYPE> Mix(const TVec4<TYPE> &x, const TVec4<TYPE> &y, const TYPE a);