Unity 6 Render Graph Scriptable Render Pass Memory Leak

Graphics Render Pipelines
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1

TLDR: Scriptable Render Pass in the new Render Graph causes memory leak, why?

Unity version 6000.2.7f2, URP version 17.2.0

I tried writing a simple gaussian blur as a render feature in Unity 6. To have an efficient shader, I use one vertical and one horizontal pass for the blur. So, the first pass should blit into a temporary texture, and the second pass blits from the temp texture back to the camera texture. The code that I wrote works fine, but I noticed that it is causing a memory leak.
I suspect it is caused by the creation of a temporary texture every frame, but according to the render graph API, the render graph handles all disposal of temp textures. Did I misunderstand how I should be using the render graph? What is the correct way to use temporary textures in the Render Graph?

The Scriptable Render Feature Code:

using UnityEngine;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering;
using UnityEngine.Rendering.RenderGraphModule;
using UnityEngine.Rendering.RenderGraphModule.Util;
using UnityEngine.Rendering.Universal;

public class GaussianOutlineRenderPass : ScriptableRenderPass
{
    const string m_PassName = "GaussianOutlineColorPass";

    Material m_BlitMaterial;

    public void Setup(Material mat)
    {
        m_BlitMaterial = mat;
        requiresIntermediateTexture = true;
    }

    public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData)
    {
        var resourceData = frameData.Get<UniversalResourceData>();
        var cameraData = frameData.Get<UniversalCameraData>();
        cameraData.requiresDepthTexture = true;

        if (resourceData.isActiveTargetBackBuffer)
        {
            Debug.LogError($"Skipping render pass. GaussianOutlineRenderFeature requires an intermediate ColorTexture, we can't use the BackBuffer as a texture input.");
            return;
        }

        var source = resourceData.activeColorTexture;

        var destinationDesc = renderGraph.GetTextureDesc(source);
        destinationDesc.name = $"CameraColor-{m_PassName}";
        destinationDesc.clearBuffer = false;
        destinationDesc.colorFormat = GraphicsFormat.R8G8B8A8_UNorm; // ensure alpha

        TextureHandle destination = renderGraph.CreateTexture(destinationDesc);

        RenderGraphUtils.BlitMaterialParameters para1 = new(source, destination, m_BlitMaterial, 0);
        renderGraph.AddBlitPass(para1, passName: m_PassName+"_1");

        RenderGraphUtils.BlitMaterialParameters para2 = new(destination, source, m_BlitMaterial, 1);
        renderGraph.AddBlitPass(para2, passName: m_PassName + "_2");
    }
}

public class GaussianOutlineRenderFeature : ScriptableRendererFeature
{    
    [Tooltip("The material used when making the blit operation.")]
    public Material material;

    [Tooltip("The event where to inject the pass.")]
    public RenderPassEvent renderPassEvent = RenderPassEvent.AfterRenderingPostProcessing;

    GaussianOutlineRenderPass m_Pass;

    public override void Create()
    {
        m_Pass = new GaussianOutlineRenderPass();

        m_Pass.renderPassEvent = renderPassEvent;
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        if (material == null)
        {
            Debug.LogWarning(this.name + " material is null and will be skipped.");
            return;
        }

        m_Pass.Setup(material);
        renderer.EnqueuePass(m_Pass);        
    }
}

I find the documentation of the Render Graph quite lacking and confusing, the only thing I needed was 2 blit passes and 1 temporary texture, and it still took me like 2 days to just make it work.

2

I have the same issue. Were you able to figure it out?

3

If you install the Memory Profiler package you can see exactly what’s gobbling up the memory. If its a render texture, you’ll find it by name there.

4

Seems like in my case I wasnt disposing of objects that should be disposed of. I was trying unified ray tracing and there seem to be objects that I need to dispose of: Sample code: Tracing camera rays | Scriptable Render Pipeline Core | 17.4.0