How to move from Graphics.DrawMeshInstanced to Graphics.RenderMeshInstanced

Question

I am trying to convert a working Graphics.DrawMeshInstanced call to Graphics.RenderMeshInstanced.

I was hoping to eventually switch it to use a NativeArray that I populate from a burst Job, but I can't get the RenderMeshInstanced call to work at all.

Anybody know the trick to it?

Answer 1

These 2 scripts results in exactly the same outcome while one is using Graphics.DrawMeshInstanced and the other Graphics.RenderMeshInstanced

alt text

LetsDrawMeshInstanced.cs

 using UnityEngine;
 
 [ExecuteAlways]
 public class LetsDrawMeshInstanced : MonoBehaviour
 {
     [SerializeField] Mesh _mesh = null;
     [SerializeField] Material _material = null;
     Matrix4x4[] _matrices = new Matrix4x4[100];
     void Update ()
     {
         if( _mesh!=null && _material!=null )
         {
             UpdateMatrices();
             Graphics.DrawMeshInstanced( _mesh , 0 , _material , _matrices );
         }
     }
     void UpdateMatrices ()
     {
         Vector3 origin = transform.position;
         float time = Time.time;
         const float tau = Mathf.PI * 2f;
         int numMatrices = _matrices.Length;
         for( int i=0 ; i<numMatrices ; i++ )
         {
             float theta = (float)i / (float)(numMatrices-1) * tau;
             _matrices[i] = Matrix4x4.TRS(
                 origin + new Vector3( 0 , Mathf.Sin(theta) , Mathf.Cos(theta) )*10f ,
                 Quaternion.Euler( new Vector3(333f,10f,333f)*time ) ,
                 Vector3.one
             );
         }
     }
 }

LetsRenderMeshInstanced.cs

 using UnityEngine;
 using Unity.Collections;
 using Unity.Jobs;
 using Unity.Mathematics;
 using BurstCompile = Unity.Burst.BurstCompileAttribute;
 
 [ExecuteAlways]
 public class LetsRenderMeshInstanced : MonoBehaviour
 {
     [SerializeField] Mesh _mesh = null;
     [SerializeField] Material _material = null;
     NativeArray<float4x4> _matrices;
     public JobHandle Dependency;
     void OnEnable ()
     {
         _matrices = new NativeArray<float4x4>( 100 , Allocator.Persistent );
     }
     void OnDisable ()
     {
         Dependency.Complete();
         if( _matrices.IsCreated ) _matrices.Dispose();
     }
     void Update ()
     {
         if( _mesh!=null && _material!=null )
         {
             // complete previous job
             Dependency.Complete();
 
             // render job results
             RenderParams rp = new RenderParams( _material );
             Graphics.RenderMeshInstanced( rp , _mesh , 0 , _matrices.Reinterpret<Matrix4x4>() );
 
             // schedule new job:
             var job = new UpdateMatrices{
                 Origin            = transform.position ,
                 Time            = Time.time ,
                 NumMatrices        = _matrices.Length ,
                 Matrices        = _matrices ,
             };
             Dependency = job.Schedule( _matrices.Length , 32 , Dependency );
         }
     }
 
     [BurstCompile]
     struct UpdateMatrices : IJobParallelFor
     {
         public float3 Origin;
         public float Time;
         public int NumMatrices;
         [WriteOnly] public NativeArray<float4x4> Matrices;
         void IJobParallelFor.Execute ( int i )
         {
             const float tau = math.PI * 2f;
             float theta = (float)i / (float)(NumMatrices-1) * tau;
             Matrices[i] = float4x4.TRS(
                 Origin + new float3( 0 , math.sin(theta) , math.cos(theta) )*10f ,
                 quaternion.Euler( math.radians(new float3(333f,10f,333f)*Time) ) ,
                 new float3(1,1,1)
             );
         }
     }
         
 }

How to move from Graphics.DrawMeshInstanced to Graphics.RenderMeshInstanced

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