This has become way easier with C++11.
template <typename T> struct Model
{
vector<T> vertices;
void transform( Matrix m )
{
for(auto &&vertex : vertices)
{
vertex.pos = m * vertex.pos;
modifyNormal(vertex, m, special_());
}
}
private:
struct general_ {};
struct special_ : general_ {};
template<typename> struct int_ { typedef int type; };
template<typename Lhs, typename Rhs,
typename int_<decltype(Lhs::normal)>::type = 0>
void modifyNormal(Lhs &&lhs, Rhs &&rhs, special_) {
lhs.normal = rhs * lhs.normal;
}
template<typename Lhs, typename Rhs>
void modifyNormal(Lhs &&lhs, Rhs &&rhs, general_) {
// do nothing
}
};
Things to note:
- You can name non-static data members in
decltype
andsizeof
without needing an object. - You can apply extended SFINAE. Basically any expression can be checked and if it is not valid when the arguments are substituted, the template is ignored.