Blur pass

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

public class DualFilteringKawaseBlurPass : BaseRenderPass
{
    private readonly TextureHandle[] _textures;
    private readonly BlurSettings _settings;
    private readonly Vector2[] _halfPixels;

    public DualFilteringKawaseBlurPass(BlurSettings settings, RenderPassEvent injectionPoint) : base(injectionPoint, "Blur Pass")
    {
        _textures = new TextureHandle[settings.Passes + 1];
        _halfPixels = new Vector2[settings.Passes + 1];
        _settings = settings;
    }

    public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData)
    {
        UniversalResourceData data = frameData.Get<UniversalResourceData>();
        TextureHandle destination = frameData.Get<TransferTexture>().Value;

        SetupBlurTextures(renderGraph, destination);
        DownSample(renderGraph);
        UpSample(renderGraph);

        data.cameraColor = destination;
    }

    private void SetupBlurTextures(RenderGraph renderGraph, TextureHandle source)
    {
        TextureDesc descriptor = renderGraph.GetTextureDesc(source);

        for (int i = 0; i < _textures.Length; ++i)
        {
            _halfPixels[i] = new Vector2(0.5f, 0.5f) / (new Vector2(descriptor.width, descriptor.height) * 0.5f);
            _textures[i] = i == 0 ? source : renderGraph.CreateTexture(descriptor);
            descriptor.width /= 2;
            descriptor.height /= 2;
        }
    }

    private void DownSample(RenderGraph renderGraph)
    {
        for (int i = 0; i < _settings.Passes; ++i)
        {
            Blit(renderGraph, i, i + 1, $"DownSample Pass {i + 1}", 0);
        }
    }

    private void UpSample(RenderGraph renderGraph)
    {
        for (int i = _settings.Passes; i > 0; --i)
        {
            Blit(renderGraph, i, i - 1, $"UpSample Pass {i + 1}", 1);
        }
    }

    private void Blit(RenderGraph renderGraph, int sourceIndex, int destinationIndex, string name, int passIndex)
    {
        RenderGraphUtils.BlitMaterialParameters parameters = new(_textures[sourceIndex], _textures[destinationIndex], _settings.Material, passIndex);
        Shader.SetGlobalVector("_HalfPixel", _settings.Offset * _halfPixels[sourceIndex]);
        renderGraph.AddBlitPass(parameters, name);
    }
}