GrabColorRendererFeature

GrabColorRendererFeature.cs

using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

/// <summary>
/// Built-in Render PipelineのGrabPassに近いRendererFeature
/// RenderObjectsRendererFeatureでGrab対象のオブジェクトを描画し、
/// そのあとにGrabColorRendererFeatureを設定することで任意のタイミングでキャプチャ、
/// 以降のシェーダーでgrabbedTextureNameで指定した名前でキャプチャしたテクスチャを参照できる
///
/// 例：Opaqueの一部のオブジェクトをキャプチャする場合、UniversalRenderDataをInspector上で以下のように設定する
/// 　1. キャプチャする対象オブジェクトに専用のレイヤー（以下GrabTargetLayer）を設定
/// 　2. UniversalRendererDataのopaqueLayerマスクからGrabTargetLayerを除外
/// 　3. RenderObjectsRendererFeatureをRenderFeatureに追加
/// 　   - EventをBeforeRenderingOpaquesにセット
/// 　   - Filters>LayerMaskでGrabTargetLayerをセット
/// 　4. 3.の次になるようにGrabColorRenderFeatureを設定
///      - RenderPassEventをBeforeRenderingOpaquesにセット
/// </summary>
public class GrabColorRendererFeature : ScriptableRendererFeature
{
    public RenderPassEvent renderPassEvent = RenderPassEvent.BeforeRenderingOpaques;
    public string grabbedTextureName = "g_GrabbedTexture";

    private GrabColorPass _pass;
    
    public override void Create()
    {
        _pass = new(grabbedTextureName, renderPassEvent);
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        renderer.EnqueuePass(_pass);
    }
    
    
    private class GrabColorPass : ScriptableRenderPass
    {
        private readonly RTHandle _textureHandle;
        private readonly int _texturePropertyId;

        public GrabColorPass(string textureName, RenderPassEvent renderPassEvent)
        {
            this.renderPassEvent = renderPassEvent;
            _texturePropertyId = Shader.PropertyToID(textureName);
            _textureHandle = RTHandles.Alloc(_texturePropertyId, textureName);
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
        {
            cmd.GetTemporaryRT(_texturePropertyId, cameraTextureDescriptor);
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            var cmd = CommandBufferPool.Get(nameof(GrabColorPass));

#if UNITY_2022_2_OR_NEWER
            var source = renderingData.cameraData.renderer.cameraColorTargetHandle;
            if (source.rt != null)
            {
                Blit(cmd, source, _textureHandle);
            }
#else
            Blit(cmd, renderingData.cameraData.renderer.cameraColorTarget, _textureHandle);
#endif
            context.ExecuteCommandBuffer(cmd);

            CommandBufferPool.Release(cmd);
        }

        public override void OnCameraCleanup(CommandBuffer cmd)
        {
            cmd.ReleaseTemporaryRT(_texturePropertyId);
        }
    }

}