I think I am too stupid to figure it out. I used an std::map<int, std::set<int>> object to store the vertices and their corrisponding skinpoints and it gave the correct number of vertices needed but I cannot seem to figure out how to store the vertex pos and normals or fill the index buffer with the new vertex values.

Since the verts and tris need to be read from seperate loops I need to store everything for access in a single loop. I got that done but storing unique vertices is proving tricky (for me).

EDIT: I have managed to create a list of all needed vertices but for some reason the list is not in the same order as the 3DGS vertex buffer. I made sure no sorting is done on the list by not using std::set.