Unity CommandBuffer.DrawMeshInstanced Does Not Work With URP

Unity Engine
,
1

I have the following code trying to test out rendering mesh manually with Unity 2020.1 using URP (I commented out mesh generation since I know that works):

public class DrawMeshTestMB : MonoBehaviour {
  [SerializeField]
  private int _width;

  [SerializeField]
  private int _height;
  private Material _material;
  private Mesh _mesh;
  private Vector3[] _vertices;
  private Vector2[] _uvs;
  private int[] _triangles;
  private List<Vector3> _positions = new List<Vector3>();
  private Matrix4x4[] _matrices;

  private List<int> _t;

  // attach OnEndCameraRendering event

  private void Awake() {
   // generate mesh / material data

   for (var x = 0; x < _width; x++) {
     for (var y = 0; y < _height; y++) {
       var matrixIndex = x + (y * x);
       var position = transform.position + new Vector3(0.45f * x, 0.7f * y);
       var rotation = Quaternion.Euler(Vector3.zero);
       var scale = Vector3.one;
      
       _positions.Add(position);

       _matrices[matrixIndex] = Matrix4x4.TRS(position, rotation, scale);
     }
   }
  }
  private void OnEndCameraRendering(ScriptableRenderContext context, Camera camera) {
   GameLogger.LogDebug("OnEndCameraRendering");
  
   CommandBuffer myCommandBuffer = new CommandBuffer();
  
   // this works
   for (var i = 0; i < _matrices.Length; i++) {
     myCommandBuffer.DrawMesh(_mesh, _matrices[i], _material, 0);
   }
  
   // this does not
   myCommandBuffer.DrawMeshInstanced(_mesh, 0, _material, -1, _matrices);
  
   Graphics.ExecuteCommandBuffer(myCommandBuffer);
  }
}

The issue I am running into in that while myCommandBuffer.DrawMesh() works, myCommandBuffer.DrawMeshInstanced() does not and I can’t find any reason why it would not. The material is GPU instancing enabled and there are no error in the console. I even look into the frame debugger and the call to render does not even show up. It is using the same data so it is not like I can creating the data differently.

Does anyone know what is wrong with my code here? Is there some weird setting that might be wrong or something not obvious?

2

DrawMeshInstanced works fine for me in URP and 2020.1 as I’ve been using it for a lot of things. I haven’t tried doing it with the endCameraRendering event so don’t know if there might be something bad there. You didn’t show your shader but I assume you also have the pragma for GPU instacing?

3

So it turn of that is has to do with the default lit shared for 2d (I am using the 2d renderer). If I use the unlit shared, that seems to work which is a bit disappointing as I really want to be able to use the 2d lighting system and trying to learn shared stuff is a bit more than I want to bite off right now.

I am going to do some profiling with just using DrawMesh() and see if that giving me the performance I am going to want since I can use the default lit shared with that called.

4

Oh that’s unfortunate. I can’t say I’ve tried using the 2D system but taking a quick glance at the sprite lit default shader for 2D and I don’t see any pragmas to enable GPU instancing.