Black RenderTextures when calling 2 the same ComputeShader in 2 Update() loops

Unity Engine
1

I’m encountering a problem when calling the same ComputeShader Dispatch() on Update() for two (or more) GameObjects.

I’ve written the following code to illustrate the issue:

// Test.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test : MonoBehaviour
{
    public ComputeShader _computeShader;
    public CustomRenderTexture _customRenderTexture;
    public Material _material;
    public Renderer _renderer;

    void Start()
    {
        _customRenderTexture = new CustomRenderTexture(256, 256);
        _customRenderTexture.enableRandomWrite = true;
        _customRenderTexture.Create();

        _material = new Material(Shader.Find("Standard"));
        _material.mainTexture = _customRenderTexture;

        _renderer = gameObject.GetComponent<Renderer>();
        _renderer.material = _material;

        _computeShader.SetTexture(0, "Result", _customRenderTexture);
        _computeShader.SetFloats("width", _customRenderTexture.width);
        _computeShader.SetFloats("height", _customRenderTexture.height);
    }

    void Update() {
        _computeShader.SetFloats("t", Time.time % 2f);
        _computeShader.Dispatch(0, _customRenderTexture.width / 8, _customRenderTexture.height / 8, 1);
    }
}

// Test.compute

#pragma kernel CSMain

float width, height;
float t;
RWTexture2D<float4> Result;

[numthreads(8,8,1)]
void CSMain (uint3 id : SV_DispatchThreadID)
{
    Result[id.xy] = float4(t * id.x / width, t * id.y / height, 0.0, 0.0);
}

Putting Test.cs/Test.compute on two planes has the following result:
clevertepidbetafish

The second plane receives only a black texture.

However, If I duplicate the Test.compute asset, and assign the new asset to Test.cs on the 2nd plane, I get this result:
similarbonyatlanticbluetang

Now both planes behave as expected.

Irregardless of if calling Dispatch() in Update() is bad practice or not, what am I doing wrong here? Is there a different way I should be instantiating my ComputeShader objects in my Test.cs script rather than assigning them in the inspector via a public variable? I hope there isn’t something painfully obvious that I’m missing.

2

I’ve found that calling:

_computeShader = ComputeShader.Instantiate(_computeShader)

Is an effective fix. But, I would still like to know if this is the correct/best way to solve this issue.