SetSubMesh Draw order

I've built a mesh with 2 submeshes (2 quads) and they seem to don't respect the order that i call Mesh.SetSubMesh.
I'm a bit confused here because if i have a mesh with a single submesh the draw order is the one from the IndexBufferData array.

I can affect the order of the submesh if i add change the supplied matrix on the next stage (Graphics.DrawMesh).

Is this a bug or am i missing something here?

Thanks

EDIT: Attached a sample project with two scenes. One where i draw 2 quads with only one submesh and another with one submesh per quad. In the second scene you can see my render order problem.

 

Thanks but i think my issue is something else.
Note that in my case i'm batching all the vertices into a single mesh using the new mesh API.
An in this case what i see is that the order of rendering is dependent on the order that i assign the vertex indices (which is fine for me). The problem arises when i have more that one submesh, this is due to requiring different materials for each submesh.

I update my mesh like this:

Code (CSharp):

1.     var vertexCount = m_vertices.Length;
2.     m_mesh.SetVertexBufferParams(
3.       vertexCount,
4.       m_meshDescriptors[0],
5.       m_meshDescriptors[1],
6.       m_meshDescriptors[2]);
7.     m_mesh.SetVertexBufferData(m_vertices, 0, 0, vertexCount, 0);
8.     m_mesh.SetIndexBufferParams(m_indices.Length, IndexFormat.UInt32);
9.     m_mesh.SetIndexBufferData(m_indices, 0, 0, m_indices.Length);
10.     m_mesh.subMeshCount = m_subMeshes.Count;
11.     for (var i = 0; i < m_subMeshes.Count; i++) {
12.       var subMesh = m_subMeshes[i];
13.       var descr = new SubMeshDescriptor() {
14.         baseVertex = 0,
15.         bounds = default,
16.         indexCount = i < m_subMeshes.Count - 1
17.               ? m_subMeshes[i + 1].Offset - subMesh.Offset
18.               : m_indices.Length - subMesh.Offset,
19.         indexStart = subMesh.Offset,
20.         topology = MeshTopology.Triangles
21.       };
22.       m_mesh.SetSubMesh(i, descr);
23.     }
24.     m_mesh.UploadMeshData(false);

My Draw code:

Code (CSharp):

1.     for (var i = 0; i < m_subMeshes.Count; ++i) {
2.       var material = m_subMeshes[i].Material;
3.       Graphics.DrawMesh(
4.         mesh: m_mesh,
5.         matrix: Matrix4x4.identity,
6.         material: material,
7.         submeshIndex: i,
8.         layer: 0,
9.         camera: Camera.main);
10.     }

My real use case for this is to draw massive amount of Text in DOTS having a single batched mesh which i already do but now i'm facing this problem sorting that text only when i have different fonts (different material).

Thanks again for your time

 

Thanks for the tip. Yeah i've looked into that before but materialIndex really is a bad naming . I was drawn away form it because i thought it could not handle submeshes. Tried it and it works fine in my sample but with DOTS i was avoiding the use of Monobehaviours at all and like that i must attach one to the camera in order to call DrawMeshNow.
Is there a place to call this using DOTS? My RenderSystem updates in PresentationSystemGroup but it wont render there.

 

Yeah ended up piping it to a monobehaviour attached to the camera that is instantiated when the Render System starts running. I had to be careful to avoid accessing dealloacted data in that monobehaviour since OnPostRender happens later in the frame and the supplied that can be invalid at that stage.

Before that tried DrawMeshInstanceIndirect (with no compute buffers other than the arguments) but it follows the same rules of rendering as DrawMesh.

It's working now and will update it as the DOTS rendering evolves. So thank you for the help!