Troubleshooting

This section provides examples of common issues you might encounter when using a Custom Pass component, and how to fix them.

Display scaling issues

A scaling issue can appear in your build when you have two cameras that do not use the same resolution. This is most common between in-game and scene views. This can happen when:

• Your code calls CommandBuffer.SetRenderTarget, and CoreUtilsSetRenderTarget sets the viewport.
• You have not multiplied by _RTHandleScale.xy in your shader code for UVs when sampling an RTHandle buffer.

To fix the causes in these cases:

• Use CoreUtils.SetRenderTarget instead of CommandBuffer.SetRenderTarget.
• Use _RTHandleScale.xy in your shader code when sampling an RTHandle buffer.

History buffer scaling issues

Scaling issues can happen when you write a custom pass that uses or modifies a history buffer. This is because history buffers use different scale properties from RTHandles (_RTHandleScale.xy). To avoid scaling issues, use _RTHandleScaleHistory.xy to sample a history buffer.

If you bind another buffer instead of a history buffer, make sure you allocate the buffer using the correct render texture size. The render texture size can be different for every camera. To get the correct size of the render texture to use for a history buffer, use HDCamera.historyRTHandleProperties.currentRenderTargetSize.

Opaque objects disappear in build

If GameObjects with an opaque material in your scene disappear when you build your program, you might need to reconfigure your HDRP Asset settings.

To fix this:

1. In the Project window, navigate to your HDRenderPipelineAsset (if you are using the default HDRP build, go to Assets > Settings).
2. In the HDRP asset, change the Lit Shader Mode to Both.

Jittering GameObjects when TAA is enabled

In some cases when Temporal anti-aliasing (TAA) is enabled, some GameObjects appear to jitter.

Jittering can happen when both of the following conditions are met:

• The object is rendered in the AfterPostProcess Injection Point . To fix this, change the Injection Point in the Custom Pass Volume component.
• The object has Depth Test enabled. To fix this, disable Depth Test in the shader properties, or set the Depth Test property in the draw renders Custom Pass component to Disabled .

Shuriken particles facing the wrong direction

The following conditions can cause particles in the scene to face the wrong direction:

• The particle system is only visible in a Custom Pass.
• There is no override implemented forAggregateCullingParameters.

Unity calculates the orientation of the particles in the Built-in Particle System when it executes AggregateCullingParameters during the culling step. Therefore, if there is no override, HRDP does not render it properly.

Decals are not visible

The following conditions can make a decal in your scene invisible:

• The decal is applied to a GameObject that Unity renders in a Custom Pass
• The decal is on a transparent object that Unity renders before the AfterOpaqueDepthAndNormal Injection point

To fix this issue, change the Injection point of the GameObject to any Injection Point after AfterOpaqueDepthAndNormal

Culling issues

If you can’t see some objects in your scene, this might be because the cullingResult you receive in the Execute method doesn’t contain objects that HDRP only renders in a Custom Pass.

This can happen if you disable the layer of your objects in the Camera Culling mask.

This happens because, by default, this cullingResult is the camera cullingResult. To fix this issue, override this method in the CustomPass class:

protected virtual void AggregateCullingParameters(ref ScriptableCullingParameters cullingParameters, HDCamera camera) {}

You can then add more layers or custom culling options to the cullingResult you receive in the Execute method using ScriptableCullingParameters .

Screen turns black when Unity loads shaders

If your screen turns black when Unity loads shaders, this could be because Unity is trying to render a shader that is not referenced in the scene. This can happen when:

• The Custom Pass only uses Shader.Find to look for your shader.
• You have not included your shader in the Resources folder.
• Your shader is not referenced in the Custom Pass.

To fix this, you can add the following lines of code to reference your shader in the Custom Pass:

   [SerializeField, HideInInspector]
   Shader shaderName;

For example:

using UnityEngine;
using UnityEngine.Rendering.HighDefinition;
using UnityEngine.Rendering;
using UnityEngine.Experimental.Rendering;

class Outline : CustomPass
{
    public LayerMask    outlineLayer = 0;
    [ColorUsage(false, true)]
    public Color        outlineColor = Color.black;
    public float        threshold = 1;

    // To make sure the shader ends up in the build, we keep a reference to it
    [SerializeField, HideInInspector]
    Shader                  outlineShader;

    Material                fullscreenOutline;
    RTHandle                outlineBuffer;

    protected override void Setup(ScriptableRenderContext renderContext, CommandBuffer cmd)
    {
        outlineShader = Shader.Find("Hidden/Outline");
        fullscreenOutline = CoreUtils.CreateEngineMaterial(outlineShader);

        // Define the outline buffer
        outlineBuffer = RTHandles.Alloc(
            Vector2.one, TextureXR.slices, dimension: TextureXR.dimension,
            colorFormat: GraphicsFormat.B10G11R11_UFloatPack32,
// We don't need alpha for this effect
            useDynamicScale: true, name: "Outline Buffer"
        );
    }

    protected override void Execute(CustomPassContext ctx)
    {
        // Render meshes we want to apply the outline effect to in the outline buffer
        CoreUtils.SetRenderTarget(ctx.cmd, outlineBuffer, ClearFlag.Color);
        CustomPassUtils.DrawRenderers(ctx, outlineLayer);

        // Set up outline effect properties
        ctx.propertyBlock.SetColor("_OutlineColor", outlineColor);
        ctx.propertyBlock.SetTexture("_OutlineBuffer", outlineBuffer);
        ctx.propertyBlock.SetFloat("_Threshold", threshold);

        // Render the outline buffer fullscreen
        CoreUtils.SetRenderTarget(ctx.cmd, ctx.cameraColorBuffer, ClearFlag.None);
        CoreUtils.DrawFullScreen(ctx.cmd, fullscreenOutline, ctx.propertyBlock, shaderPassId: 0);
    }

    protected override void Cleanup()
    {
        CoreUtils.Destroy(fullscreenOutline);
        outlineBuffer.Release();
    }
}