How to get rendered LOD mesh for entity?

Unity Engine
1

I am trying to get the actively rendered mesh sub-entity from an entity with a MeshLODGroupComponent, is there any way to retrieve this?

I have had a quick look through LodRequirementsUpdateSystem, InstancedRenderMeshBatchGroup, and RenderMeshSystemV2, but I don’t fully understand what’s going in there yet. Do I need to retrieve it from the chunk data?

Alternatively can I just do the lod calculation myself to pick which mesh is used?

2

This is my current solution, but the LOD index doesn’t exactly match what’s rendered:

public static class EcsRenderingHelper
{
    /// <summary> Calculate the index of the visible LOD. </summary>
    public static int CalculateLodIndex(MeshLODGroupComponent meshLODGroup, float4x4 localToWorld, float3 cameraPos)
    {
        var worldRef = math.transform(localToWorld, meshLODGroup.LocalReferencePoint);
        var dist = math.distance(cameraPos, worldRef);

        if (dist < meshLODGroup.LODDistances0.x) return 0;
        if (dist < meshLODGroup.LODDistances0.y) return 1;
        if (dist < meshLODGroup.LODDistances0.z) return 2;
        if (dist < meshLODGroup.LODDistances0.w) return 3;
        if (dist < meshLODGroup.LODDistances1.x) return 4;
        if (dist < meshLODGroup.LODDistances1.y) return 5;
        if (dist < meshLODGroup.LODDistances1.z) return 6;
        if (dist < meshLODGroup.LODDistances1.w) return 7;

        // no mesh rendered
        return -1;
    }

    public static Entity FindRenderedChild(EntityManager entityManager, Entity rootEntity, int lodMask)
    {
        var children = entityManager.GetBuffer<Child>(rootEntity);

        for (int childIndex = 0; childIndex < children.Length; ++childIndex)
        {
            var childEntity = children[childIndex].Value;

            if (entityManager.HasComponent<MeshLODComponent>(childEntity))
            {
                var meshlodComponent = entityManager.GetComponentData<MeshLODComponent>(childEntity);
                if ((meshlodComponent.LODMask & lodMask) != 0)
                {
                    return childEntity;
                }
            }
        }

        return Entity.Null;
    }
}