unity – Frustum culling using compute shader, how?

I’m working on a little project for a while – creating an area where you can spawn a bunch of grass. I’ve overcame a major headache when figuring out the GPU instancing for the mesh and the code looks like this:

public class Grass : MonoBehaviour
{
    [HideInInspector]
    public Mesh mesh;
    [HideInInspector]
    public List<Matrix4x4> matrices;
    [HideInInspector]
    public Material material;

    private void Update()
    {
        Graphics.DrawMeshInstanced(mesh, 0, material, matrices);
    }
}

Now that I’m done with this part I want to optimize things. Shaders of any kind and me are complete strangers so I’m asking for anyone’s help on writing a compute shader that would work with my code to simulate frustum culling.

Thanks!