Question Custom Effect with sorting options with PostProcessing V2

I have also written a selective custom effect and I am wondering how to manipulate with its order.
The custom effect template does not seem to provide an option to set an order variable, even with a limited options (BeforeStack, BeforeTransparent and AfterStack).
Depending on the selected V2 effect - my custom effect should be ordered once before, or the other time after.
How to add an order option to it?

Code (CSharp):

1. using System;
2. using UnityEngine;
3. using UnityEngine.Rendering.PostProcessing;
4.  
5. [Serializable]
6. [PostProcess(typeof(GrayscaleRenderer), PostProcessEvent.AfterStack, "Custom/Grayscale")]
7. public sealed class Grayscale : PostProcessEffectSettings
8. {
9.   [Range(0f, 1f), Tooltip("Grayscale effect intensity.")]
10.    public FloatParameter blend = new FloatParameter { value = 0.5f };
11. }
12. public sealed class GrayscaleRenderer : PostProcessEffectRenderer<Grayscale>
13. {
14.    public override void Render(PostProcessRenderContext context)
15.   {
16.        var sheet = context.propertySheets.Get(Shader.Find("Hidden/Custom/Grayscale"));
17.        sheet.properties.SetFloat("_Blend", settings.blend);
18.        context.command.BlitFullscreenTriangle(context.source, context.destination, sheet, 0);
19.   }
20. }

This is the template from https://docs.unity3d.com/Packages/com.unity.postprocessing@3.0/manual/Writing-Custom-Effects.html

 

You can set the sorting order for custom effects on the PostProcessLayer camera component. It's tucked away under the foldout menus.

 

Is it possible to set it here?
The sorting order is here already imposed by the effect script.



When trying to use a variable instead of constant in the script template, I am getting this error:
error CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type

Looks like it would have to be compiled separately for each sorting order?

 

Ah, you mean tying the PostProcessEvent enum to a variable? That's unfortunately not possible, class attributes always need to use constant values. Definitely a limitation imposed by how PPSv2 is designed.

It may be possible to hack in with C# reflection and move an effect from the m_BeforeStackBundles list to m_AfterStackBundles (and vice versa). Then call InitBundles().