Graphics.RenderMeshInstanced with additional custom data

[placid pasture]

Hi, I've been using Graphics.RenderMeshInstanced to draw instanced meshes, my shader is simple. Now how can I add a new custom float to each instance?

I looked into https://docs.unity3d.com/6000.2/Documentation/ScriptReference/Graphics.RenderMeshInstanced.html but it doesn't go into details about the custom weight property.
I also saw some advise about using MaterialPropertyBlock but that system doesn't yet support NativeArray so I rather find an alternative.

Right now I'm just using my NativeList<Matrix4x4> _matrices with the Graphics.RenderMeshInstanced function and its pretty good. I wonder if I can keep it in the same quality and add custom data to the instances.

++ standard render pipeline

if it matters, right now my shader is also pretty simple and follows the standards

v2f vert(appdata v)
{
    v2f o;
    UNITY_SETUP_INSTANCE_ID(v);
    UNITY_TRANSFER_INSTANCE_ID(v, o);
    o.vertex = UnityObjectToClipPos(v.vertex);
    return o;
}

fixed4 frag(v2f i) : SV_Target
{
    UNITY_SETUP_INSTANCE_ID(i);
    return fixed4(1, 1, 1, _Opacity);
}

ideally I'd like to have a float t in the frag which is instanced. and ideally I'd like to not use managed List or Array in the C# side for that! and also, ideally not using the Indirect rendering methods!

Thanks in advance! 😅🙏 messages got a little long, so let me know if it needs to be summarized and shortened

[drifting cargo]

Are you on Unity 6.2? You need to make GraphicsBuffer, upload your data in it, and index it in shader using uint instanceID: SV_InstanceID index. For Unity 6.3 there is new option available called Render Shader User Value: https://discussions.unity.com/t/renderer-shader-user-value-customize-your-visual-per-renderer/1682526

[placid pasture]

Thanks!
Then we'd need to go with StructuredBuffer<float> for the shader too, right?

[drifting cargo]

Yes

[placid pasture]

With the other approach, the good thing about it was it handled size and capacity automatically.

the Graphics.RenderMeshInstanced with NativeArray<Matrix4x4> as its T

I guess there's no running away from StructuredBuffer

Thanks again 🙏

[drifting cargo]

Unfortunately no. But it is not that hard as it seems at first.

[placid pasture]

Hey, just wanted to say that indeed it was easier than I thought and it's implemented. Thanks again! For sake of referencing, this video helped a lot too (Unity Japan is such a treasure!) on the ordering of the API callings and that we need to use the material's SetBuffer and not the RenderParameter's matProp's

[placid pasture]

so this is 100,000 lines drawn every frame 😅