data/Packages/com.unity.render-pipelines.universal/Runtime/RendererFeatures/FullScreenPassRendererFeature.cs

using System;
using UnityEngine.Rendering.RenderGraphModule;
using UnityEngine.Experimental.Rendering;

namespace UnityEngine.Rendering.Universal
{
    /// <summary>
    /// This renderer feature lets you create single-pass full screen post processing effects without needing to write code.
    /// </summary>
    [URPHelpURL("renderer-features/renderer-feature-full-screen-pass")]
    public partial class FullScreenPassRendererFeature : ScriptableRendererFeature
    {
        /// <summary>
        /// An injection point for the full screen pass. This is similar to the RenderPassEvent enum but limited to only supported events.
        /// </summary>
        public enum InjectionPoint
        {
            /// <summary>
            /// Inject a full screen pass before transparents are rendered.
            /// </summary>
            BeforeRenderingTransparents = RenderPassEvent.BeforeRenderingTransparents,

            /// <summary>
            /// Inject a full screen pass before post processing is rendered.
            /// </summary>
            BeforeRenderingPostProcessing = RenderPassEvent.BeforeRenderingPostProcessing,

            /// <summary>
            /// Inject a full screen pass after post processing is rendered.
            /// </summary>
            AfterRenderingPostProcessing = RenderPassEvent.AfterRenderingPostProcessing
        }

        /// <summary>
        /// Specifies at which injection point the pass will be rendered.
        /// </summary>
        public InjectionPoint injectionPoint = InjectionPoint.AfterRenderingPostProcessing;

        /// <summary>
        /// Specifies whether the assigned material will need to use the current screen contents as an input texture.
        /// Disable this to optimize away an extra color copy pass when you know that the assigned material will only need
        /// to write on top of or hardware blend with the contents of the active color target.
        /// </summary>
        public bool fetchColorBuffer = true;

        /// <summary>
        /// A mask of URP textures that the assigned material will need access to. Requesting unused requirements can degrade
        /// performance unnecessarily as URP might need to run additional rendering passes to generate them.
        /// </summary>
        public ScriptableRenderPassInput requirements = ScriptableRenderPassInput.None;

        /// <summary>
        /// The material used to render the full screen pass (typically based on the Fullscreen Shader Graph target).
        /// </summary>
        public Material passMaterial;

        /// <summary>
        /// The shader pass index that should be used when rendering the assigned material.
        /// </summary>
        public int passIndex = 0;

        /// <summary>
        /// Specifies if the active camera's depth-stencil buffer should be bound when rendering the full screen pass.
        /// Disabling this will ensure that the material's depth and stencil commands will have no effect (this could also have a slight performance benefit).
        /// </summary>
        public bool bindDepthStencilAttachment = false;

        private FullScreenRenderPass m_FullScreenPass;

        /// <inheritdoc/>
        public override void Create()
        {
            m_FullScreenPass = new FullScreenRenderPass(name);
        }

        internal override bool RequireRenderingLayers(bool isDeferred, bool needsGBufferAccurateNormals, out RenderingLayerUtils.Event atEvent, out RenderingLayerUtils.MaskSize maskSize)
        {
            atEvent = RenderingLayerUtils.Event.Opaque;
            maskSize = RenderingLayerUtils.MaskSize.Bits8;
            return false;
        }

        /// <inheritdoc/>
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            if (renderingData.cameraData.cameraType == CameraType.Preview
                || renderingData.cameraData.cameraType == CameraType.Reflection
                || UniversalRenderer.IsOffscreenDepthTexture(ref renderingData.cameraData))
                return;

            if (passMaterial == null)
            {
                Debug.LogWarningFormat("The full screen feature \"{0}\" will not execute - no material is assigned. Please make sure a material is assigned for this feature on the renderer asset.", name);
                return;
            }

            if (passIndex < 0 || passIndex >= passMaterial.passCount)
            {
                Debug.LogWarningFormat("The full screen feature \"{0}\" will not execute - the pass index is out of bounds for the material.", name);
                return;
            }

            m_FullScreenPass.renderPassEvent = (RenderPassEvent)injectionPoint;
            m_FullScreenPass.ConfigureInput(requirements);
            m_FullScreenPass.SetupMembers(passMaterial, passIndex, fetchColorBuffer, bindDepthStencilAttachment);

            m_FullScreenPass.requiresIntermediateTexture = fetchColorBuffer;
        
            renderer.EnqueuePass(m_FullScreenPass);
        }

        /// <inheritdoc/>
        protected override void Dispose(bool disposing)
        {
            m_FullScreenPass.Dispose();
        }

        internal class FullScreenRenderPass : ScriptableRenderPass
        {
            private Material m_Material;
            private int m_PassIndex;
            private bool m_FetchActiveColor;
            private bool m_BindDepthStencilAttachment;
            private RTHandle m_CopiedColor;

            private static MaterialPropertyBlock s_SharedPropertyBlock = new MaterialPropertyBlock();

            public FullScreenRenderPass(string passName)
            {
                profilingSampler = new ProfilingSampler(passName);
            }

            public void SetupMembers(Material material, int passIndex, bool fetchActiveColor, bool bindDepthStencilAttachment)
            {
                m_Material = material;
                m_PassIndex = passIndex;
                m_FetchActiveColor = fetchActiveColor;
                m_BindDepthStencilAttachment = bindDepthStencilAttachment;
            }

            [Obsolete(DeprecationMessage.CompatibilityScriptingAPIObsolete, false)]
            public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
            {
                // Disable obsolete warning for internal usage
                #pragma warning disable CS0618
                // FullScreenPass manages its own RenderTarget.
                // ResetTarget here so that ScriptableRenderer's active attachement can be invalidated when processing this ScriptableRenderPass.
                ResetTarget();
                #pragma warning restore CS0618

                if (m_FetchActiveColor)
                    ReAllocate(renderingData.cameraData.cameraTargetDescriptor);
            }

            internal void ReAllocate(RenderTextureDescriptor desc)
            {
                desc.msaaSamples = 1;
                desc.depthStencilFormat = GraphicsFormat.None;
                RenderingUtils.ReAllocateHandleIfNeeded(ref m_CopiedColor, desc, name: "_FullscreenPassColorCopy");
            }

            public void Dispose()
            {
                m_CopiedColor?.Release();
            }

            private static void ExecuteCopyColorPass(RasterCommandBuffer cmd, RTHandle sourceTexture)
            {
                Blitter.BlitTexture(cmd, sourceTexture, new Vector4(1, 1, 0, 0), 0.0f, false);
            }

            private static void ExecuteMainPass(RasterCommandBuffer cmd, RTHandle sourceTexture, Material material, int passIndex)
            {
                s_SharedPropertyBlock.Clear();
                if (sourceTexture != null)
                    s_SharedPropertyBlock.SetTexture(ShaderPropertyId.blitTexture, sourceTexture);

                // We need to set the "_BlitScaleBias" uniform for user materials with shaders relying on core Blit.hlsl to work
                s_SharedPropertyBlock.SetVector(ShaderPropertyId.blitScaleBias, new Vector4(1, 1, 0, 0));

                cmd.DrawProcedural(Matrix4x4.identity, material, passIndex, MeshTopology.Triangles, 3, 1, s_SharedPropertyBlock);
            }

            [Obsolete(DeprecationMessage.CompatibilityScriptingAPIObsolete, false)]
            public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
            {
                ref var cameraData = ref renderingData.cameraData;
                var cmd = renderingData.commandBuffer;

                using (new ProfilingScope(cmd, profilingSampler))
                {
                    RasterCommandBuffer rasterCmd = CommandBufferHelpers.GetRasterCommandBuffer(cmd);
                    if (m_FetchActiveColor)
                    {
                        CoreUtils.SetRenderTarget(cmd, m_CopiedColor);
                        ExecuteCopyColorPass(rasterCmd, cameraData.renderer.cameraColorTargetHandle);
                    }

                    if (m_BindDepthStencilAttachment)
                        CoreUtils.SetRenderTarget(cmd, cameraData.renderer.cameraColorTargetHandle, cameraData.renderer.cameraDepthTargetHandle);
                    else
                        CoreUtils.SetRenderTarget(cmd, cameraData.renderer.cameraColorTargetHandle);

                    ExecuteMainPass(rasterCmd, m_FetchActiveColor ? m_CopiedColor : null, m_Material, m_PassIndex);
                }
            }

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

                TextureHandle source, destination;

                Debug.Assert(resourcesData.cameraColor.IsValid());

                if (m_FetchActiveColor)
                {
                    var targetDesc = renderGraph.GetTextureDesc(resourcesData.cameraColor);
                    targetDesc.name = "_CameraColorFullScreenPass";
                    targetDesc.clearBuffer = false;

                    source = resourcesData.activeColorTexture;
                    destination = renderGraph.CreateTexture(targetDesc);
                
                    using (var builder = renderGraph.AddRasterRenderPass<CopyPassData>("Copy Color Full Screen", out var passData, profilingSampler))
                    {
                        passData.inputTexture = source;
                        builder.UseTexture(passData.inputTexture, AccessFlags.Read);

                        builder.SetRenderAttachment(destination, 0, AccessFlags.Write);

                        builder.SetRenderFunc((CopyPassData data, RasterGraphContext rgContext) =>
                        {
                            ExecuteCopyColorPass(rgContext.cmd, data.inputTexture);
                        });
                    }

                    //Swap for next pass;
                    source = destination;                
                }
                else
                {
                    source = TextureHandle.nullHandle;
                }

                destination = resourcesData.activeColorTexture;


                using (var builder = renderGraph.AddRasterRenderPass<MainPassData>(passName, out var passData, profilingSampler))
                {
                    passData.material = m_Material;
                    passData.passIndex = m_PassIndex;

                    passData.inputTexture = source;

                    if(passData.inputTexture.IsValid())
                        builder.UseTexture(passData.inputTexture, AccessFlags.Read);

                    bool needsColor = (input & ScriptableRenderPassInput.Color) != ScriptableRenderPassInput.None;
                    bool needsDepth = (input & ScriptableRenderPassInput.Depth) != ScriptableRenderPassInput.None;
                    bool needsMotion = (input & ScriptableRenderPassInput.Motion) != ScriptableRenderPassInput.None;
                    bool needsNormal = (input & ScriptableRenderPassInput.Normal) != ScriptableRenderPassInput.None;

                    if (needsColor && cameraData.renderer.SupportsCameraOpaque())
                    {
                        Debug.Assert(resourcesData.cameraOpaqueTexture.IsValid());
                        builder.UseTexture(resourcesData.cameraOpaqueTexture);
                    }

                    if (needsDepth)
                    {
                        Debug.Assert(resourcesData.cameraDepthTexture.IsValid());
                        builder.UseTexture(resourcesData.cameraDepthTexture);
                    }

                    if (needsMotion)
                    {
                        Debug.Assert(cameraData.renderer.SupportsMotionVectors(), "Current renderer does not support motion vectors.");

                        if (cameraData.renderer.SupportsMotionVectors())
                        {
                            Debug.Assert(resourcesData.motionVectorColor.IsValid());
                            builder.UseTexture(resourcesData.motionVectorColor);
                            Debug.Assert(resourcesData.motionVectorDepth.IsValid());
                            builder.UseTexture(resourcesData.motionVectorDepth);
                        }
                    }

                    if (needsNormal && cameraData.renderer.SupportsCameraNormals())
                    {
                        Debug.Assert(resourcesData.cameraNormalsTexture.IsValid());
                        builder.UseTexture(resourcesData.cameraNormalsTexture);
                    }
                
                    builder.SetRenderAttachment(destination, 0, AccessFlags.Write);

                    if (m_BindDepthStencilAttachment)
                        builder.SetRenderAttachmentDepth(resourcesData.activeDepthTexture, AccessFlags.Write);

                    builder.SetRenderFunc((MainPassData data, RasterGraphContext rgContext) =>
                    {
                        ExecuteMainPass(rgContext.cmd, data.inputTexture, data.material, data.passIndex);
                    });                
                }
            }

            private class CopyPassData
            {
                internal TextureHandle inputTexture;
            }

            private class MainPassData
            {
                internal Material material;
                internal int passIndex;
                internal TextureHandle inputTexture;
            }
        }
    }
}