Bug [HDRP] Ambient probe is not applied to meshes, rendered using Graphics.DrawMesh

Hello,

This is the expected behavior, the lighting information isn't available when you do Graphics.DrawMesh or cmd.DrawMesh. You need to use this instead: https://docs.unity3d.com/ScriptReference/Rendering.ScriptableRenderContext.DrawRenderers.html
It has the PerObjectData attribute that you can use to select which lighting data you want to use:
https://docs.unity3d.com/ScriptReference/Rendering.PerObjectData.html

 

It depends on what you want to do. For unlit objects, the approach you mentioned may be fine but for Lit objects that require to be rendered multiple times by HDRP (depth pre-pass, buffer, motion vectors, etc.) it won't work. So I recommend using Graphics.DrawMesh() and similar functions, internally these calls will register what you're trying to render as part of the things to render in your scene and thus will be included in the DrawRenderers() calls HDRP does.

So something like this works quite well:

Code (CSharp):

1. using UnityEngine;
2.  
3. public class DrawMesh : MonoBehaviour
4. {
5.     public Mesh mesh;
6.     public Material material;
7.  
8.     void Update()
9.     {
10.         Graphics.DrawMesh(mesh, Vector3.zero, Quaternion.identity, material, 1);
11.     }
12. }
13.  

Note that some things still don't work with this approach as Graphics.DrawMesh() doesn't have enough parameters to handle everything (like light layers for example) and motion vectors might be broken too, especially with DrawProcedural.

 

Sorry, I misunderstood the problem, I confused myself between the DrawMesh from CommandBuffer and Graphics. Graphics.DrawMesh should support ambient probe indeed as well as light/shadows in realtime or baked setup because it's directly passed to DrawRenderers()

I did a quick test with HDRP 10 and it seems to work for me (tested sky ambient, light probes, baked and realtime light/shadows, and reflection probes). Could you elaborate on the setup you're using so we can find a repro?

Btw I confirm that DrawMeshInstanced doesn't work with lighting and shadows.

 

Yes, it's a bug that the DrawMeshInstanced doesn't work in your version.

I investigated a bit the case and it's the light layers (I disabled them in the HDRP asset and it worked). It has probably something to do with the default value of the light layers because you can't provide a value for them with Graphics.Draw* calls.