Member function of Earcut Assumes that the point type has a size member function
gracicot opened this issue · comments
Namely, the functions Earcut<N>::operator() and Earcut<N>::linkedList are using points[i].size(), but it is documented that specializing the nth is enough to make it compatible.
I propose adding a constexpr static member function in nth that returns the size. By default it should return std::tuple_size<T>::value. Adding a new struct that has a ::value static data member is also an option.
Tell me which one you prefer and I'll create a pull request :)
I think there's some confusion about the types.
The input type for earcut has a structure like vector<vector<point>>. For the point type, it's sufficient if nth<0, ...> and nth<1, ...> is defined. For the vector type, it's necessary to define container methods such as 'size', operator[] etc.
Namely, the functions Earcut::operator() and Earcut::linkedList are using points[i].size(), but it is documented that specializing the nth is enough to make it compatible.
points[i] would be a vector, therefore points[i].size() is the number of points of the polygon/point-list/vector with the index i.
Hmm, right now I'm trying to send a std::vector<glm::vec2>. I would need to send a std::vector<std::vector<glm::vec2>>? What is the second dimension is supposed to represent? I'm not sure how to layout my data
Ah! I see, this is to support holes inside a polygon?
Yes, to support holes. The first vector<point> is the main surrounding polygon, further point-lists define holes.
std::vector<std::vector<glm::vec2>> would work.
Perfect! Sorry for the noise.
For the records, since I'm not supporting holes in my application, I opted to send std::span<std::vector<glm::vec2>, 1>{std::addressof(points), 1}, where points is a std::vector<glm::vec2>