Question Mesh importer, SetVertexBufferData with dynamic vertex size

Hi,
for context, I'am working on a mesh importer for a custom format that allows me to pass arbitrary mesh data from blender.

When creating the mesh in unity I have some difficulties passing my vertex data to the mesh:
SetVertexBufferData expect an array of struct matching my data size. I first tried to generate a dynamic structure with reflection and TypeBuilder, but that's really complicated and shouldn't be required just to pass some data.

Then I assumed that a plain bytes array should be enough, so I pushed all my vertices data into a
MemoryStream and then just passed my memStream.ToArray() to SetVertexBufferData. it works for the first n bytes of my model, where n is the total number of declared vertex. for example my test mesh have 125 vertices declared and a vertex is 20 bytes, so my first 6 vertex are actually correct in the resulting mesh (6x20=120) and I get random garbage from the 7th.

So what is the proper way to call SetVertexBufferData when you can't actually declare a static struct format like described in the documentation ?

 

This is the master piece I came up with (to expand to infinity), until I get the courage to dive into dynamicly generated Type again or someone finally explains me the obvious way of doing it that I missed.

Code (CSharp):

1.     struct Struct16 { public int _4, _8, _12, _16; }
2.     struct Struct20 { public int _4, _8, _12, _16, _20; }
3.  
4.     T[] ConvertByteToStructArray<T>(byte[] data, int size, int count) where T : struct
5.     {
6.         T[] dataStruct = new T[count];
7.         for (int i = 0; i < count; i++)
8.         {
9.             IntPtr ptPoit = Marshal.AllocHGlobal(size);
10.             Marshal.Copy(data, i * size, ptPoit, size);
11.             dataStruct[i] = (T) Marshal.PtrToStructure(ptPoit, typeof (T));
12.             Marshal.FreeHGlobal(ptPoit);
13.         }
14.         return dataStruct;
15.     }
16.  
17.     void SetVertexBufferData(Mesh mesh, byte[] verticesData, int size, int count)
18.     {
19.         switch (size)
20.         {
21.             case 16: mesh.SetVertexBufferData(ConvertByteToStructArray<Struct16>(verticesData, size, count), 0, 0, count); break;
22.             case 20: mesh.SetVertexBufferData(ConvertByteToStructArray<Struct20>(verticesData, size, count), 0, 0, count); break;
23.         }
24.     }

 

Maybe you can assign the attributes separately with the old accessor methods (Mesh.vertices, Mesh.normals, Mesh.colors, Mesh.normals, Mesh.tangents, Mesh.uv, Mesh.uv2, ....)?

 

That would work for position but I can't because these methods are typed and I use my texcoord for everything (byte, float, integers, ....) and not just vector2