using System;
using System.Diagnostics;
using System.Collections.Generic;
using Unity.Collections;
using UnityEngine.Profiling;

namespace UnityEngine.Rendering.Universal
{
    /// <summary>
    ///  Class <c>ScriptableRenderer</c> implements a rendering strategy. It describes how culling and lighting works and
    /// the effects supported.
    ///
    ///  A renderer can be used for all cameras or be overridden on a per-camera basis. It will implement light culling and setup
    /// and describe a list of <c>ScriptableRenderPass</c> to execute in a frame. The renderer can be extended to support more effect with additional
    ///  <c>ScriptableRendererFeature</c>. Resources for the renderer are serialized in <c>ScriptableRendererData</c>.
    ///
    /// he renderer resources are serialized in <c>ScriptableRendererData</c>.
    /// <seealso cref="ScriptableRendererData"/>
    /// <seealso cref="ScriptableRendererFeature"/>
    /// <seealso cref="ScriptableRenderPass"/>
    /// </summary>
    public abstract partial class ScriptableRenderer : IDisposable
    {
        private static class Profiling
        {
            private const string k_Name = nameof(ScriptableRenderer);
            public static readonly ProfilingSampler setPerCameraShaderVariables = new ProfilingSampler($"{k_Name}.{nameof(SetPerCameraShaderVariables)}");
            public static readonly ProfilingSampler sortRenderPasses            = new ProfilingSampler($"Sort Render Passes");
            public static readonly ProfilingSampler setupLights                 = new ProfilingSampler($"{k_Name}.{nameof(SetupLights)}");
            public static readonly ProfilingSampler setupCamera                 = new ProfilingSampler($"Setup Camera Parameters");
            public static readonly ProfilingSampler addRenderPasses             = new ProfilingSampler($"{k_Name}.{nameof(AddRenderPasses)}");
            public static readonly ProfilingSampler clearRenderingState         = new ProfilingSampler($"{k_Name}.{nameof(ClearRenderingState)}");
            public static readonly ProfilingSampler internalStartRendering      = new ProfilingSampler($"{k_Name}.{nameof(InternalStartRendering)}");
            public static readonly ProfilingSampler internalFinishRendering     = new ProfilingSampler($"{k_Name}.{nameof(InternalFinishRendering)}");

            public static class RenderBlock
            {
                private const string k_Name = nameof(RenderPassBlock);
                public static readonly ProfilingSampler beforeRendering          = new ProfilingSampler($"{k_Name}.{nameof(RenderPassBlock.BeforeRendering)}");
                public static readonly ProfilingSampler mainRenderingOpaque      = new ProfilingSampler($"{k_Name}.{nameof(RenderPassBlock.MainRenderingOpaque)}");
                public static readonly ProfilingSampler mainRenderingTransparent = new ProfilingSampler($"{k_Name}.{nameof(RenderPassBlock.MainRenderingTransparent)}");
                public static readonly ProfilingSampler afterRendering           = new ProfilingSampler($"{k_Name}.{nameof(RenderPassBlock.AfterRendering)}");
            }

            public static class RenderPass
            {
                private const string k_Name = nameof(ScriptableRenderPass);
                public static readonly ProfilingSampler configure = new ProfilingSampler($"{k_Name}.{nameof(ScriptableRenderPass.Configure)}");
            }
        }

        /// <summary>
        /// Override to provide a custom profiling name
        /// </summary>
        protected ProfilingSampler profilingExecute { get; set; }

        /// <summary>
        /// Configures the supported features for this renderer. When creating custom renderers
        /// for Universal Render Pipeline you can choose to opt-in or out for specific features.
        /// </summary>
        public class RenderingFeatures
        {
            /// <summary>
            /// This setting controls if the camera editor should display the camera stack category.
            /// Renderers that don't support camera stacking will only render camera of type CameraRenderType.Base
            /// <see cref="CameraRenderType"/>
            /// <seealso cref="UniversalAdditionalCameraData.cameraStack"/>
            /// </summary>
            public bool cameraStacking { get; set; } = false;

            /// <summary>
            /// This setting controls if the Universal Render Pipeline asset should expose MSAA option.
            /// </summary>
            public bool msaa { get; set; } = true;
        }

        /// <summary>
        /// The renderer we are currently rendering with, for low-level render control only.
        /// <c>current</c> is null outside rendering scope.
        /// Similar to https://docs.unity3d.com/ScriptReference/Camera-current.html
        /// </summary>
        internal static ScriptableRenderer current = null;

        /// <summary>
        /// Set camera matrices. This method will set <c>UNITY_MATRIX_V</c>, <c>UNITY_MATRIX_P</c>, <c>UNITY_MATRIX_VP</c> to camera matrices.
        /// Additionally this will also set <c>unity_CameraProjection</c> and <c>unity_CameraProjection</c>.
        /// If <c>setInverseMatrices</c> is set to true this function will also set <c>UNITY_MATRIX_I_V</c> and <c>UNITY_MATRIX_I_VP</c>.
        /// This function has no effect when rendering in stereo. When in stereo rendering you cannot override camera matrices.
        /// If you need to set general purpose view and projection matrices call <see cref="SetViewAndProjectionMatrices(CommandBuffer, Matrix4x4, Matrix4x4, bool)"/> instead.
        /// </summary>
        /// <param name="cmd">CommandBuffer to submit data to GPU.</param>
        /// <param name="cameraData">CameraData containing camera matrices information.</param>
        /// <param name="setInverseMatrices">Set this to true if you also need to set inverse camera matrices.</param>
        public static void SetCameraMatrices(CommandBuffer cmd, ref CameraData cameraData, bool setInverseMatrices)
        {
#if ENABLE_VR && ENABLE_XR_MODULE
            if (cameraData.xr.enabled)
            {
                cameraData.xr.UpdateGPUViewAndProjectionMatrices(cmd, ref cameraData, cameraData.xr.renderTargetIsRenderTexture);
                return;
            }
#endif

            Matrix4x4 viewMatrix = cameraData.GetViewMatrix();
            Matrix4x4 projectionMatrix = cameraData.GetProjectionMatrix();

            // TODO: Investigate why SetViewAndProjectionMatrices is causing y-flip / winding order issue
            // for now using cmd.SetViewProjecionMatrices
            //SetViewAndProjectionMatrices(cmd, viewMatrix, cameraData.GetDeviceProjectionMatrix(), setInverseMatrices);
            cmd.SetViewProjectionMatrices(viewMatrix, projectionMatrix);

            if (setInverseMatrices)
            {
                Matrix4x4 gpuProjectionMatrix = cameraData.GetGPUProjectionMatrix();
                Matrix4x4 viewAndProjectionMatrix = gpuProjectionMatrix * viewMatrix;
                Matrix4x4 inverseViewMatrix = Matrix4x4.Inverse(viewMatrix);
                Matrix4x4 inverseProjectionMatrix = Matrix4x4.Inverse(gpuProjectionMatrix);
                Matrix4x4 inverseViewProjection = inverseViewMatrix * inverseProjectionMatrix;

                // There's an inconsistency in handedness between unity_matrixV and unity_WorldToCamera
                // Unity changes the handedness of unity_WorldToCamera (see Camera::CalculateMatrixShaderProps)
                // we will also change it here to avoid breaking existing shaders. (case 1257518)
                Matrix4x4 worldToCameraMatrix = Matrix4x4.Scale(new Vector3(1.0f, 1.0f, -1.0f)) * viewMatrix;
                Matrix4x4 cameraToWorldMatrix = worldToCameraMatrix.inverse;
                cmd.SetGlobalMatrix(ShaderPropertyId.worldToCameraMatrix, worldToCameraMatrix);
                cmd.SetGlobalMatrix(ShaderPropertyId.cameraToWorldMatrix, cameraToWorldMatrix);

                cmd.SetGlobalMatrix(ShaderPropertyId.inverseViewMatrix, inverseViewMatrix);
                cmd.SetGlobalMatrix(ShaderPropertyId.inverseProjectionMatrix, inverseProjectionMatrix);
                cmd.SetGlobalMatrix(ShaderPropertyId.inverseViewAndProjectionMatrix, inverseViewProjection);
            }

            // TODO: missing unity_CameraWorldClipPlanes[6], currently set by context.SetupCameraProperties
        }

        /// <summary>
        /// Set camera and screen shader variables as described in https://docs.unity3d.com/Manual/SL-UnityShaderVariables.html
        /// </summary>
        /// <param name="cmd">CommandBuffer to submit data to GPU.</param>
        /// <param name="cameraData">CameraData containing camera matrices information.</param>
        void SetPerCameraShaderVariables(CommandBuffer cmd, ref CameraData cameraData)
        {
            using var profScope = new ProfilingScope(cmd, Profiling.setPerCameraShaderVariables);

            Camera camera = cameraData.camera;

            Rect pixelRect = cameraData.pixelRect;
            float renderScale = cameraData.isSceneViewCamera ? 1f : cameraData.renderScale;
            float scaledCameraWidth = (float)pixelRect.width * renderScale;
            float scaledCameraHeight = (float)pixelRect.height * renderScale;
            float cameraWidth = (float)pixelRect.width;
            float cameraHeight = (float)pixelRect.height;

            // Use eye texture's width and height as screen params when XR is enabled
            if (cameraData.xr.enabled)
            {
                scaledCameraWidth = (float)cameraData.cameraTargetDescriptor.width;
                scaledCameraHeight = (float)cameraData.cameraTargetDescriptor.height;
                cameraWidth = (float)cameraData.cameraTargetDescriptor.width;
                cameraHeight = (float)cameraData.cameraTargetDescriptor.height;
            }

            if (camera.allowDynamicResolution)
            {
                scaledCameraWidth *= ScalableBufferManager.widthScaleFactor;
                scaledCameraHeight *= ScalableBufferManager.heightScaleFactor;
            }

            float near = camera.nearClipPlane;
            float far = camera.farClipPlane;
            float invNear = Mathf.Approximately(near, 0.0f) ? 0.0f : 1.0f / near;
            float invFar = Mathf.Approximately(far, 0.0f) ? 0.0f : 1.0f / far;
            float isOrthographic = camera.orthographic ? 1.0f : 0.0f;

            // From http://www.humus.name/temp/Linearize%20depth.txt
            // But as depth component textures on OpenGL always return in 0..1 range (as in D3D), we have to use
            // the same constants for both D3D and OpenGL here.
            // OpenGL would be this:
            // zc0 = (1.0 - far / near) / 2.0;
            // zc1 = (1.0 + far / near) / 2.0;
            // D3D is this:
            float zc0 = 1.0f - far * invNear;
            float zc1 = far * invNear;

            Vector4 zBufferParams = new Vector4(zc0, zc1, zc0 * invFar, zc1 * invFar);

            if (SystemInfo.usesReversedZBuffer)
            {
                zBufferParams.y += zBufferParams.x;
                zBufferParams.x = -zBufferParams.x;
                zBufferParams.w += zBufferParams.z;
                zBufferParams.z = -zBufferParams.z;
            }

            // Projection flip sign logic is very deep in GfxDevice::SetInvertProjectionMatrix
            // For now we don't deal with _ProjectionParams.x and let SetupCameraProperties handle it.
            // We need to enable this when we remove SetupCameraProperties
            // float projectionFlipSign = ???
            // Vector4 projectionParams = new Vector4(projectionFlipSign, near, far, 1.0f * invFar);
            // cmd.SetGlobalVector(ShaderPropertyId.projectionParams, projectionParams);

            Vector4 orthoParams = new Vector4(camera.orthographicSize * cameraData.aspectRatio, camera.orthographicSize, 0.0f, isOrthographic);

            // Camera and Screen variables as described in https://docs.unity3d.com/Manual/SL-UnityShaderVariables.html
            cmd.SetGlobalVector(ShaderPropertyId.worldSpaceCameraPos, camera.transform.position);
            cmd.SetGlobalVector(ShaderPropertyId.screenParams, new Vector4(cameraWidth, cameraHeight, 1.0f + 1.0f / cameraWidth, 1.0f + 1.0f / cameraHeight));
            cmd.SetGlobalVector(ShaderPropertyId.scaledScreenParams, new Vector4(scaledCameraWidth, scaledCameraHeight, 1.0f + 1.0f / scaledCameraWidth, 1.0f + 1.0f / scaledCameraHeight));
            cmd.SetGlobalVector(ShaderPropertyId.zBufferParams, zBufferParams);
            cmd.SetGlobalVector(ShaderPropertyId.orthoParams, orthoParams);
        }

        /// <summary>
        /// Set shader time variables as described in https://docs.unity3d.com/Manual/SL-UnityShaderVariables.html
        /// </summary>
        /// <param name="cmd">CommandBuffer to submit data to GPU.</param>
        /// <param name="time">Time.</param>
        /// <param name="deltaTime">Delta time.</param>
        /// <param name="smoothDeltaTime">Smooth delta time.</param>
        void SetShaderTimeValues(CommandBuffer cmd, float time, float deltaTime, float smoothDeltaTime)
        {
            float timeEights = time / 8f;
            float timeFourth = time / 4f;
            float timeHalf = time / 2f;

            // Time values
            Vector4 timeVector = time * new Vector4(1f / 20f, 1f, 2f, 3f);
            Vector4 sinTimeVector = new Vector4(Mathf.Sin(timeEights), Mathf.Sin(timeFourth), Mathf.Sin(timeHalf), Mathf.Sin(time));
            Vector4 cosTimeVector = new Vector4(Mathf.Cos(timeEights), Mathf.Cos(timeFourth), Mathf.Cos(timeHalf), Mathf.Cos(time));
            Vector4 deltaTimeVector = new Vector4(deltaTime, 1f / deltaTime, smoothDeltaTime, 1f / smoothDeltaTime);
            Vector4 timeParametersVector = new Vector4(time, Mathf.Sin(time), Mathf.Cos(time), 0.0f);

            cmd.SetGlobalVector(ShaderPropertyId.time, timeVector);
            cmd.SetGlobalVector(ShaderPropertyId.sinTime, sinTimeVector);
            cmd.SetGlobalVector(ShaderPropertyId.cosTime, cosTimeVector);
            cmd.SetGlobalVector(ShaderPropertyId.deltaTime, deltaTimeVector);
            cmd.SetGlobalVector(ShaderPropertyId.timeParameters, timeParametersVector);
        }

        /// <summary>
        /// Returns the camera color target for this renderer.
        /// It's only valid to call cameraColorTarget in the scope of <c>ScriptableRenderPass</c>.
        /// <seealso cref="ScriptableRenderPass"/>.
        /// </summary>
        public RenderTargetIdentifier cameraColorTarget
        {
            get
            {
                if (!(m_IsPipelineExecuting || isCameraColorTargetValid))
                {
                    Debug.LogWarning("You can only call cameraColorTarget inside the scope of a ScriptableRenderPass. Otherwise the pipeline camera target texture might have not been created or might have already been disposed.");
                    // TODO: Ideally we should return an error texture (BuiltinRenderTextureType.None?)
                    // but this might break some existing content, so we return the pipeline texture in the hope it gives a "soft" upgrade to users.
                }

                return m_CameraColorTarget;
            }
        }

        /// <summary>
        /// Returns the camera depth target for this renderer.
        /// It's only valid to call cameraDepthTarget in the scope of <c>ScriptableRenderPass</c>.
        /// <seealso cref="ScriptableRenderPass"/>.
        /// </summary>
        public RenderTargetIdentifier cameraDepthTarget
        {
            get
            {
                if (!m_IsPipelineExecuting)
                {
                    Debug.LogWarning("You can only call cameraDepthTarget inside the scope of a ScriptableRenderPass. Otherwise the pipeline camera target texture might have not been created or might have already been disposed.");
                    // TODO: Ideally we should return an error texture (BuiltinRenderTextureType.None?)
                    // but this might break some existing content, so we return the pipeline texture in the hope it gives a "soft" upgrade to users.
                }

                return m_CameraDepthTarget;
            }
        }

        /// <summary>
        /// Returns a list of renderer features added to this renderer.
        /// <seealso cref="ScriptableRendererFeature"/>
        /// </summary>
        protected List<ScriptableRendererFeature> rendererFeatures
        {
            get => m_RendererFeatures;
        }

        /// <summary>
        /// Returns a list of render passes scheduled to be executed by this renderer.
        /// <seealso cref="ScriptableRenderPass"/>
        /// </summary>
        protected List<ScriptableRenderPass> activeRenderPassQueue
        {
            get => m_ActiveRenderPassQueue;
        }

        /// <summary>
        /// Supported rendering features by this renderer.
        /// <see cref="SupportedRenderingFeatures"/>
        /// </summary>
        public RenderingFeatures supportedRenderingFeatures { get; set; } = new RenderingFeatures();

        /// <summary>
        /// List of unsupported Graphics APIs for this renderer.
        /// <see cref="unsupportedGraphicsDeviceTypes"/>
        /// </summary>
        public GraphicsDeviceType[] unsupportedGraphicsDeviceTypes { get; set; } = new GraphicsDeviceType[0];

        static class RenderPassBlock
        {
            // Executes render passes that are inputs to the main rendering
            // but don't depend on camera state. They all render in monoscopic mode. f.ex, shadow maps.
            public static readonly int BeforeRendering = 0;

            // Main bulk of render pass execution. They required camera state to be properly set
            // and when enabled they will render in stereo.
            public static readonly int MainRenderingOpaque = 1;
            public static readonly int MainRenderingTransparent = 2;

            // Execute after Post-processing.
            public static readonly int AfterRendering = 3;
        }

        const int k_RenderPassBlockCount = 4;

        List<ScriptableRenderPass> m_ActiveRenderPassQueue = new List<ScriptableRenderPass>(32);
        List<ScriptableRendererFeature> m_RendererFeatures = new List<ScriptableRendererFeature>(10);
        RenderTargetIdentifier m_CameraColorTarget;
        RenderTargetIdentifier m_CameraDepthTarget;

        bool m_FirstTimeCameraColorTargetIsBound = true; // flag used to track when m_CameraColorTarget should be cleared (if necessary), as well as other special actions only performed the first time m_CameraColorTarget is bound as a render target
        bool m_FirstTimeCameraDepthTargetIsBound = true; // flag used to track when m_CameraDepthTarget should be cleared (if necessary), the first time m_CameraDepthTarget is bound as a render target

        // The pipeline can only guarantee the camera target texture are valid when the pipeline is executing.
        // Trying to access the camera target before or after might be that the pipeline texture have already been disposed.
        bool m_IsPipelineExecuting = false;
        // This should be removed when early camera color target assignment is removed.
        internal bool isCameraColorTargetValid = false;

        static RenderTargetIdentifier[] m_ActiveColorAttachments = new RenderTargetIdentifier[] {0, 0, 0, 0, 0, 0, 0, 0 };
        static RenderTargetIdentifier m_ActiveDepthAttachment;

        // CommandBuffer.SetRenderTarget(RenderTargetIdentifier[] colors, RenderTargetIdentifier depth, int mipLevel, CubemapFace cubemapFace, int depthSlice);
        // called from CoreUtils.SetRenderTarget will issue a warning assert from native c++ side if "colors" array contains some invalid RTIDs.
        // To avoid that warning assert we trim the RenderTargetIdentifier[] arrays we pass to CoreUtils.SetRenderTarget.
        // To avoid re-allocating a new array every time we do that, we re-use one of these arrays:
        static RenderTargetIdentifier[][] m_TrimmedColorAttachmentCopies = new RenderTargetIdentifier[][]
        {
            new RenderTargetIdentifier[0],                          // m_TrimmedColorAttachmentCopies[0] is an array of 0 RenderTargetIdentifier - only used to make indexing code easier to read
            new RenderTargetIdentifier[] {0},                        // m_TrimmedColorAttachmentCopies[1] is an array of 1 RenderTargetIdentifier
            new RenderTargetIdentifier[] {0, 0},                     // m_TrimmedColorAttachmentCopies[2] is an array of 2 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0},                  // m_TrimmedColorAttachmentCopies[3] is an array of 3 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0, 0},               // m_TrimmedColorAttachmentCopies[4] is an array of 4 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0, 0, 0},            // m_TrimmedColorAttachmentCopies[5] is an array of 5 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0, 0, 0, 0},         // m_TrimmedColorAttachmentCopies[6] is an array of 6 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0, 0, 0, 0, 0},      // m_TrimmedColorAttachmentCopies[7] is an array of 7 RenderTargetIdentifiers
            new RenderTargetIdentifier[] {0, 0, 0, 0, 0, 0, 0, 0 },  // m_TrimmedColorAttachmentCopies[8] is an array of 8 RenderTargetIdentifiers
        };

        internal static void ConfigureActiveTarget(RenderTargetIdentifier colorAttachment,
            RenderTargetIdentifier depthAttachment)
        {
            m_ActiveColorAttachments[0] = colorAttachment;
            for (int i = 1; i < m_ActiveColorAttachments.Length; ++i)
                m_ActiveColorAttachments[i] = 0;

            m_ActiveDepthAttachment = depthAttachment;
        }

        public ScriptableRenderer(ScriptableRendererData data)
        {
            profilingExecute = new ProfilingSampler($"{nameof(ScriptableRenderer)}.{nameof(ScriptableRenderer.Execute)}: {data.name}");

            foreach (var feature in data.rendererFeatures)
            {
                if (feature == null)
                    continue;

                feature.Create();
                m_RendererFeatures.Add(feature);
            }
            Clear(CameraRenderType.Base);
            m_ActiveRenderPassQueue.Clear();
        }

        public void Dispose()
        {
            // Dispose all renderer features...
            for (int i = 0; i < m_RendererFeatures.Count; ++i)
            {
                if (rendererFeatures[i] == null)
                    continue;

                rendererFeatures[i].Dispose();
            }

            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
        }

        /// <summary>
        /// Configures the camera target.
        /// </summary>
        /// <param name="colorTarget">Camera color target. Pass BuiltinRenderTextureType.CameraTarget if rendering to backbuffer.</param>
        /// <param name="depthTarget">Camera depth target. Pass BuiltinRenderTextureType.CameraTarget if color has depth or rendering to backbuffer.</param>
        public void ConfigureCameraTarget(RenderTargetIdentifier colorTarget, RenderTargetIdentifier depthTarget)
        {
            m_CameraColorTarget = colorTarget;
            m_CameraDepthTarget = depthTarget;
        }

        // This should be removed when early camera color target assignment is removed.
        internal void ConfigureCameraColorTarget(RenderTargetIdentifier colorTarget)
        {
            m_CameraColorTarget = colorTarget;
        }

        /// <summary>
        /// Configures the render passes that will execute for this renderer.
        /// This method is called per-camera every frame.
        /// </summary>
        /// <param name="context">Use this render context to issue any draw commands during execution.</param>
        /// <param name="renderingData">Current render state information.</param>
        /// <seealso cref="ScriptableRenderPass"/>
        /// <seealso cref="ScriptableRendererFeature"/>
        public abstract void Setup(ScriptableRenderContext context, ref RenderingData renderingData);

        /// <summary>
        /// Override this method to implement the lighting setup for the renderer. You can use this to
        /// compute and upload light CBUFFER for example.
        /// </summary>
        /// <param name="context">Use this render context to issue any draw commands during execution.</param>
        /// <param name="renderingData">Current render state information.</param>
        public virtual void SetupLights(ScriptableRenderContext context, ref RenderingData renderingData)
        {
        }

        /// <summary>
        /// Override this method to configure the culling parameters for the renderer. You can use this to configure if
        /// lights should be culled per-object or the maximum shadow distance for example.
        /// </summary>
        /// <param name="cullingParameters">Use this to change culling parameters used by the render pipeline.</param>
        /// <param name="cameraData">Current render state information.</param>
        public virtual void SetupCullingParameters(ref ScriptableCullingParameters cullingParameters,
            ref CameraData cameraData)
        {
        }

        /// <summary>
        /// Called upon finishing rendering the camera stack. You can release any resources created by the renderer here.
        /// </summary>
        /// <param name="cmd"></param>
        public virtual void FinishRendering(CommandBuffer cmd)
        {
        }

        /// <summary>
        /// Execute the enqueued render passes. This automatically handles editor and stereo rendering.
        /// </summary>
        /// <param name="context">Use this render context to issue any draw commands during execution.</param>
        /// <param name="renderingData">Current render state information.</param>
        public void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            m_IsPipelineExecuting = true;
            ref CameraData cameraData = ref renderingData.cameraData;
            Camera camera = cameraData.camera;

            CommandBuffer cmd = CommandBufferPool.Get();

            // TODO: move skybox code from C++ to URP in order to remove the call to context.Submit() inside DrawSkyboxPass
            // Until then, we can't use nested profiling scopes with XR multipass
            CommandBuffer cmdScope = renderingData.cameraData.xr.enabled ? null : cmd;

            using (new ProfilingScope(cmdScope, profilingExecute))
            {
                InternalStartRendering(context, ref renderingData);

                // Cache the time for after the call to `SetupCameraProperties` and set the time variables in shader
                // For now we set the time variables per camera, as we plan to remove `SetupCameraProperties`.
                // Setting the time per frame would take API changes to pass the variable to each camera render.
                // Once `SetupCameraProperties` is gone, the variable should be set higher in the call-stack.
#if UNITY_EDITOR
                float time = Application.isPlaying ? Time.time : Time.realtimeSinceStartup;
#else
                float time = Time.time;
#endif
                float deltaTime = Time.deltaTime;
                float smoothDeltaTime = Time.smoothDeltaTime;

                // Initialize Camera Render State
                ClearRenderingState(cmd);
                SetPerCameraShaderVariables(cmd, ref cameraData);
                SetShaderTimeValues(cmd, time, deltaTime, smoothDeltaTime);
                context.ExecuteCommandBuffer(cmd);
                cmd.Clear();
                using (new ProfilingScope(cmd, Profiling.sortRenderPasses))
                {
                    // Sort the render pass queue
                    SortStable(m_ActiveRenderPassQueue);
                }

                using var renderBlocks = new RenderBlocks(m_ActiveRenderPassQueue);

                using (new ProfilingScope(cmd, Profiling.setupLights))
                {
                    SetupLights(context, ref renderingData);
                }

                using (new ProfilingScope(cmd, Profiling.RenderBlock.beforeRendering))
                {
                    // Before Render Block. This render blocks always execute in mono rendering.
                    // Camera is not setup. Lights are not setup.
                    // Used to render input textures like shadowmaps.
                    ExecuteBlock(RenderPassBlock.BeforeRendering, in renderBlocks, context, ref renderingData);
                }

                using (new ProfilingScope(cmd, Profiling.setupCamera))
                {
                    // This is still required because of the following reasons:
                    // - Camera billboard properties.
                    // - Camera frustum planes: unity_CameraWorldClipPlanes[6]
                    // - _ProjectionParams.x logic is deep inside GfxDevice
                    // NOTE: The only reason we have to call this here and not at the beginning (before shadows)
                    // is because this need to be called for each eye in multi pass VR.
                    // The side effect is that this will override some shader properties we already setup and we will have to
                    // reset them.
                    context.SetupCameraProperties(camera);
                    SetCameraMatrices(cmd, ref cameraData, true);

                    // Reset shader time variables as they were overridden in SetupCameraProperties. If we don't do it we might have a mismatch between shadows and main rendering
                    SetShaderTimeValues(cmd, time, deltaTime, smoothDeltaTime);

#if VISUAL_EFFECT_GRAPH_0_0_1_OR_NEWER
                    //Triggers dispatch per camera, all global parameters should have been setup at this stage.
                    VFX.VFXManager.ProcessCameraCommand(camera, cmd);
#endif
                }

                context.ExecuteCommandBuffer(cmd);
                cmd.Clear();

                BeginXRRendering(cmd, context, ref renderingData.cameraData);

                // In the opaque and transparent blocks the main rendering executes.

                // Opaque blocks...
                if (renderBlocks.GetLength(RenderPassBlock.MainRenderingOpaque) > 0)
                {
                    using var profScope = new ProfilingScope(cmd, Profiling.RenderBlock.mainRenderingOpaque);
                    ExecuteBlock(RenderPassBlock.MainRenderingOpaque, in renderBlocks, context, ref renderingData);
                }

                // Transparent blocks...
                if (renderBlocks.GetLength(RenderPassBlock.MainRenderingTransparent) > 0)
                {
                    using var profScope = new ProfilingScope(cmd, Profiling.RenderBlock.mainRenderingTransparent);
                    ExecuteBlock(RenderPassBlock.MainRenderingTransparent, in renderBlocks, context, ref renderingData);
                }

                // Draw Gizmos...
                DrawGizmos(context, camera, GizmoSubset.PreImageEffects);

                // In this block after rendering drawing happens, e.g, post processing, video player capture.
                if (renderBlocks.GetLength(RenderPassBlock.AfterRendering) > 0)
                {
                    using var profScope = new ProfilingScope(cmd, Profiling.RenderBlock.afterRendering);
                    ExecuteBlock(RenderPassBlock.AfterRendering, in renderBlocks, context, ref renderingData);
                }

                EndXRRendering(cmd, context, ref renderingData.cameraData);

                DrawWireOverlay(context, camera);
                DrawGizmos(context, camera, GizmoSubset.PostImageEffects);

                InternalFinishRendering(context, cameraData.resolveFinalTarget);
            }

            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }

        /// <summary>
        /// Enqueues a render pass for execution.
        /// </summary>
        /// <param name="pass">Render pass to be enqueued.</param>
        public void EnqueuePass(ScriptableRenderPass pass)
        {
            m_ActiveRenderPassQueue.Add(pass);
        }

        /// <summary>
        /// Returns a clear flag based on CameraClearFlags.
        /// </summary>
        /// <param name="cameraClearFlags">Camera clear flags.</param>
        /// <returns>A clear flag that tells if color and/or depth should be cleared.</returns>
        protected static ClearFlag GetCameraClearFlag(ref CameraData cameraData)
        {
            var cameraClearFlags = cameraData.camera.clearFlags;

            // Universal RP doesn't support CameraClearFlags.DepthOnly and CameraClearFlags.Nothing.
            // CameraClearFlags.DepthOnly has the same effect of CameraClearFlags.SolidColor
            // CameraClearFlags.Nothing clears Depth on PC/Desktop and in mobile it clears both
            // depth and color.
            // CameraClearFlags.Skybox clears depth only.

            // Implementation details:
            // Camera clear flags are used to initialize the attachments on the first render pass.
            // ClearFlag is used together with Tile Load action to figure out how to clear the camera render target.
            // In Tile Based GPUs ClearFlag.Depth + RenderBufferLoadAction.DontCare becomes DontCare load action.
            // While ClearFlag.All + RenderBufferLoadAction.DontCare become Clear load action.
            // In mobile we force ClearFlag.All as DontCare doesn't have noticeable perf. difference from Clear
            // and this avoid tile clearing issue when not rendering all pixels in some GPUs.
            // In desktop/consoles there's actually performance difference between DontCare and Clear.

            // RenderBufferLoadAction.DontCare in PC/Desktop behaves as not clearing screen
            // RenderBufferLoadAction.DontCare in Vulkan/Metal behaves as DontCare load action
            // RenderBufferLoadAction.DontCare in GLES behaves as glInvalidateBuffer

            // Overlay cameras composite on top of previous ones. They don't clear color.
            // For overlay cameras we check if depth should be cleared on not.
            if (cameraData.renderType == CameraRenderType.Overlay)
                return (cameraData.clearDepth) ? ClearFlag.Depth : ClearFlag.None;

            // Always clear on first render pass in mobile as it's same perf of DontCare and avoid tile clearing issues.
            if (Application.isMobilePlatform)
                return ClearFlag.All;

            if ((cameraClearFlags == CameraClearFlags.Skybox && RenderSettings.skybox != null) ||
                cameraClearFlags == CameraClearFlags.Nothing)
                return ClearFlag.Depth;

            return ClearFlag.All;
        }

        /// <summary>
        /// Calls <c>AddRenderPasses</c> for each feature added to this renderer.
        /// <seealso cref="ScriptableRendererFeature.AddRenderPasses(ScriptableRenderer, ref RenderingData)"/>
        /// </summary>
        /// <param name="renderingData"></param>
        protected void AddRenderPasses(ref RenderingData renderingData)
        {
            using var profScope = new ProfilingScope(null, Profiling.addRenderPasses);

            // Add render passes from custom renderer features
            for (int i = 0; i < rendererFeatures.Count; ++i)
            {
                if (!rendererFeatures[i].isActive)
                {
                    continue;
                }
                rendererFeatures[i].AddRenderPasses(this, ref renderingData);
            }

            // Remove any null render pass that might have been added by user by mistake
            int count = activeRenderPassQueue.Count;
            for (int i = count - 1; i >= 0; i--)
            {
                if (activeRenderPassQueue[i] == null)
                    activeRenderPassQueue.RemoveAt(i);
            }
        }

        void ClearRenderingState(CommandBuffer cmd)
        {
            using var profScope = new ProfilingScope(cmd, Profiling.clearRenderingState);

            // Reset per-camera shader keywords. They are enabled depending on which render passes are executed.
            cmd.DisableShaderKeyword(ShaderKeywordStrings.MainLightShadows);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.MainLightShadowCascades);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.MainLightShadowScreen);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.AdditionalLightsVertex);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.AdditionalLightsPixel);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.AdditionalLightShadows);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.SoftShadows);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.MixedLightingSubtractive); // Backward compatibility
            cmd.DisableShaderKeyword(ShaderKeywordStrings.LightmapShadowMixing);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.ShadowsShadowMask);
            cmd.DisableShaderKeyword(ShaderKeywordStrings.LinearToSRGBConversion);
        }

        internal void Clear(CameraRenderType cameraType)
        {
            m_ActiveColorAttachments[0] = BuiltinRenderTextureType.CameraTarget;
            for (int i = 1; i < m_ActiveColorAttachments.Length; ++i)
                m_ActiveColorAttachments[i] = 0;

            m_ActiveDepthAttachment = BuiltinRenderTextureType.CameraTarget;

            m_FirstTimeCameraColorTargetIsBound = cameraType == CameraRenderType.Base;
            m_FirstTimeCameraDepthTargetIsBound = true;

            m_CameraColorTarget = BuiltinRenderTextureType.CameraTarget;
            m_CameraDepthTarget = BuiltinRenderTextureType.CameraTarget;
        }

        void ExecuteBlock(int blockIndex, in RenderBlocks renderBlocks,
            ScriptableRenderContext context, ref RenderingData renderingData, bool submit = false)
        {
            foreach (int currIndex in renderBlocks.GetRange(blockIndex))
            {
                var renderPass = m_ActiveRenderPassQueue[currIndex];
                ExecuteRenderPass(context, renderPass, ref renderingData);
            }

            if (submit)
                context.Submit();
        }

        void ExecuteRenderPass(ScriptableRenderContext context, ScriptableRenderPass renderPass, ref RenderingData renderingData)
        {
            using var profScope = new ProfilingScope(null, renderPass.profilingSampler);

            ref CameraData cameraData = ref renderingData.cameraData;

            CommandBuffer cmd = CommandBufferPool.Get();

            // Track CPU only as GPU markers for this scope were "too noisy".
            using (new ProfilingScope(cmd, Profiling.RenderPass.configure))
            {
                renderPass.Configure(cmd, cameraData.cameraTargetDescriptor);
                SetRenderPassAttachments(cmd, renderPass, ref cameraData);
            }

            // Also, we execute the commands recorded at this point to ensure SetRenderTarget is called before RenderPass.Execute
            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);

            renderPass.Execute(context, ref renderingData);
        }

        void SetRenderPassAttachments(CommandBuffer cmd, ScriptableRenderPass renderPass, ref CameraData cameraData)
        {
            Camera camera = cameraData.camera;
            ClearFlag cameraClearFlag = GetCameraClearFlag(ref cameraData);

            // Invalid configuration - use current attachment setup
            // Note: we only check color buffers. This is only technically correct because for shadowmaps and depth only passes
            // we bind depth as color and Unity handles it underneath. so we never have a situation that all color buffers are null and depth is bound.
            uint validColorBuffersCount = RenderingUtils.GetValidColorBufferCount(renderPass.colorAttachments);
            if (validColorBuffersCount == 0)
                return;

            // We use a different code path for MRT since it calls a different version of API SetRenderTarget
            if (RenderingUtils.IsMRT(renderPass.colorAttachments))
            {
                // In the MRT path we assume that all color attachments are REAL color attachments,
                // and that the depth attachment is a REAL depth attachment too.


                // Determine what attachments need to be cleared. ----------------

                bool needCustomCameraColorClear = false;
                bool needCustomCameraDepthClear = false;

                int cameraColorTargetIndex = RenderingUtils.IndexOf(renderPass.colorAttachments, m_CameraColorTarget);
                if (cameraColorTargetIndex != -1 && (m_FirstTimeCameraColorTargetIsBound))
                {
                    m_FirstTimeCameraColorTargetIsBound = false; // register that we did clear the camera target the first time it was bound

                    // Overlay cameras composite on top of previous ones. They don't clear.
                    // MTT: Commented due to not implemented yet
                    //                    if (renderingData.cameraData.renderType == CameraRenderType.Overlay)
                    //                        clearFlag = ClearFlag.None;

                    // We need to specifically clear the camera color target.
                    // But there is still a chance we don't need to issue individual clear() on each render-targets if they all have the same clear parameters.
                    needCustomCameraColorClear = (cameraClearFlag & ClearFlag.Color) != (renderPass.clearFlag & ClearFlag.Color)
                        || CoreUtils.ConvertSRGBToActiveColorSpace(camera.backgroundColor) != renderPass.clearColor;
                }

                // Note: if we have to give up the assumption that no depthTarget can be included in the MRT colorAttachments, we might need something like this:
                // int cameraTargetDepthIndex = IndexOf(renderPass.colorAttachments, m_CameraDepthTarget);
                // if( !renderTargetAlreadySet && cameraTargetDepthIndex != -1 && m_FirstTimeCameraDepthTargetIsBound)
                // { ...
                // }

                if (renderPass.depthAttachment == m_CameraDepthTarget && m_FirstTimeCameraDepthTargetIsBound)
                {
                    m_FirstTimeCameraDepthTargetIsBound = false;
                    needCustomCameraDepthClear = (cameraClearFlag & ClearFlag.Depth) != (renderPass.clearFlag & ClearFlag.Depth);
                }

                // Perform all clear operations needed. ----------------
                // We try to minimize calls to SetRenderTarget().

                // We get here only if cameraColorTarget needs to be handled separately from the rest of the color attachments.
                if (needCustomCameraColorClear)
                {
                    // Clear camera color render-target separately from the rest of the render-targets.

                    if ((cameraClearFlag & ClearFlag.Color) != 0)
                        SetRenderTarget(cmd, renderPass.colorAttachments[cameraColorTargetIndex], renderPass.depthAttachment, ClearFlag.Color, CoreUtils.ConvertSRGBToActiveColorSpace(camera.backgroundColor));

                    if ((renderPass.clearFlag & ClearFlag.Color) != 0)
                    {
                        uint otherTargetsCount = RenderingUtils.CountDistinct(renderPass.colorAttachments, m_CameraColorTarget);
                        var nonCameraAttachments = m_TrimmedColorAttachmentCopies[otherTargetsCount];
                        int writeIndex = 0;
                        for (int readIndex = 0; readIndex < renderPass.colorAttachments.Length; ++readIndex)
                        {
                            if (renderPass.colorAttachments[readIndex] != m_CameraColorTarget && renderPass.colorAttachments[readIndex] != 0)
                            {
                                nonCameraAttachments[writeIndex] = renderPass.colorAttachments[readIndex];
                                ++writeIndex;
                            }
                        }

                        if (writeIndex != otherTargetsCount)
                            Debug.LogError("writeIndex and otherTargetsCount values differed. writeIndex:" + writeIndex + " otherTargetsCount:" + otherTargetsCount);
                        SetRenderTarget(cmd, nonCameraAttachments, m_CameraDepthTarget, ClearFlag.Color, renderPass.clearColor);
                    }
                }

                // Bind all attachments, clear color only if there was no custom behaviour for cameraColorTarget, clear depth as needed.
                ClearFlag finalClearFlag = ClearFlag.None;
                finalClearFlag |= needCustomCameraDepthClear ? (cameraClearFlag & ClearFlag.Depth) : (renderPass.clearFlag & ClearFlag.Depth);
                finalClearFlag |= needCustomCameraColorClear ? 0 : (renderPass.clearFlag & ClearFlag.Color);

                // Only setup render target if current render pass attachments are different from the active ones.
                if (!RenderingUtils.SequenceEqual(renderPass.colorAttachments, m_ActiveColorAttachments) || renderPass.depthAttachment != m_ActiveDepthAttachment || finalClearFlag != ClearFlag.None)
                {
                    int lastValidRTindex = RenderingUtils.LastValid(renderPass.colorAttachments);
                    if (lastValidRTindex >= 0)
                    {
                        int rtCount = lastValidRTindex + 1;
                        var trimmedAttachments = m_TrimmedColorAttachmentCopies[rtCount];
                        for (int i = 0; i < rtCount; ++i)
                            trimmedAttachments[i] = renderPass.colorAttachments[i];
                        SetRenderTarget(cmd, trimmedAttachments, renderPass.depthAttachment, finalClearFlag, renderPass.clearColor);

                    #if ENABLE_VR && ENABLE_XR_MODULE
                        if (cameraData.xr.enabled)
                        {
                            // SetRenderTarget might alter the internal device state(winding order).
                            // Non-stereo buffer is already updated internally when switching render target. We update stereo buffers here to keep the consistency.
                            int xrTargetIndex = RenderingUtils.IndexOf(renderPass.colorAttachments, cameraData.xr.renderTarget);
                            bool isRenderToBackBufferTarget = (xrTargetIndex != -1) && !cameraData.xr.renderTargetIsRenderTexture;
                            cameraData.xr.UpdateGPUViewAndProjectionMatrices(cmd, ref cameraData, !isRenderToBackBufferTarget);
                        }
                    #endif
                    }
                }
            }
            else
            {
                // Currently in non-MRT case, color attachment can actually be a depth attachment.

                RenderTargetIdentifier passColorAttachment = renderPass.colorAttachment;
                RenderTargetIdentifier passDepthAttachment = renderPass.depthAttachment;

                // When render pass doesn't call ConfigureTarget we assume it's expected to render to camera target
                // which might be backbuffer or the framebuffer render textures.
                if (!renderPass.overrideCameraTarget)
                {
                    // Default render pass attachment for passes before main rendering is current active
                    // early return so we don't change current render target setup.
                    if (renderPass.renderPassEvent < RenderPassEvent.BeforeRenderingOpaques)
                        return;

                    // Otherwise default is the pipeline camera target.
                    passColorAttachment = m_CameraColorTarget;
                    passDepthAttachment = m_CameraDepthTarget;
                }

                ClearFlag finalClearFlag = ClearFlag.None;
                Color finalClearColor;

                if (passColorAttachment == m_CameraColorTarget && (m_FirstTimeCameraColorTargetIsBound))
                {
                    m_FirstTimeCameraColorTargetIsBound = false; // register that we did clear the camera target the first time it was bound

                    finalClearFlag |= (cameraClearFlag & ClearFlag.Color);
                    finalClearColor = CoreUtils.ConvertSRGBToActiveColorSpace(camera.backgroundColor);

                    if (m_FirstTimeCameraDepthTargetIsBound)
                    {
                        // m_CameraColorTarget can be an opaque pointer to a RenderTexture with depth-surface.
                        // We cannot infer this information here, so we must assume both camera color and depth are first-time bound here (this is the legacy behaviour).
                        m_FirstTimeCameraDepthTargetIsBound = false;
                        finalClearFlag |= (cameraClearFlag & ClearFlag.Depth);
                    }
                }
                else
                {
                    finalClearFlag |= (renderPass.clearFlag & ClearFlag.Color);
                    finalClearColor = renderPass.clearColor;
                }

                // Condition (m_CameraDepthTarget!=BuiltinRenderTextureType.CameraTarget) below prevents m_FirstTimeCameraDepthTargetIsBound flag from being reset during non-camera passes (such as Color Grading LUT). This ensures that in those cases, cameraDepth will actually be cleared during the later camera pass.
                if ((m_CameraDepthTarget != BuiltinRenderTextureType.CameraTarget) && (passDepthAttachment == m_CameraDepthTarget || passColorAttachment == m_CameraDepthTarget) && m_FirstTimeCameraDepthTargetIsBound)
                {
                    m_FirstTimeCameraDepthTargetIsBound = false;

                    finalClearFlag |= (cameraClearFlag & ClearFlag.Depth);

                    // finalClearFlag |= (cameraClearFlag & ClearFlag.Color);  // <- m_CameraDepthTarget is never a color-surface, so no need to add this here.
                }
                else
                    finalClearFlag |= (renderPass.clearFlag & ClearFlag.Depth);

                // Only setup render target if current render pass attachments are different from the active ones
                if (passColorAttachment != m_ActiveColorAttachments[0] || passDepthAttachment != m_ActiveDepthAttachment || finalClearFlag != ClearFlag.None)
                {
                    SetRenderTarget(cmd, passColorAttachment, passDepthAttachment, finalClearFlag, finalClearColor);

#if ENABLE_VR && ENABLE_XR_MODULE
                    if (cameraData.xr.enabled)
                    {
                        // SetRenderTarget might alter the internal device state(winding order).
                        // Non-stereo buffer is already updated internally when switching render target. We update stereo buffers here to keep the consistency.
                        bool isRenderToBackBufferTarget = (passColorAttachment == cameraData.xr.renderTarget) && !cameraData.xr.renderTargetIsRenderTexture;
                        cameraData.xr.UpdateGPUViewAndProjectionMatrices(cmd, ref cameraData, !isRenderToBackBufferTarget);
                    }
#endif
                }
            }
        }

        void BeginXRRendering(CommandBuffer cmd, ScriptableRenderContext context, ref CameraData cameraData)
        {
#if ENABLE_VR && ENABLE_XR_MODULE
            if (cameraData.xr.enabled)
            {
                cameraData.xr.StartSinglePass(cmd);
                cmd.EnableShaderKeyword(ShaderKeywordStrings.UseDrawProcedural);
                context.ExecuteCommandBuffer(cmd);
                cmd.Clear();
            }
#endif
        }

        void EndXRRendering(CommandBuffer cmd, ScriptableRenderContext context, ref CameraData cameraData)
        {
#if ENABLE_VR && ENABLE_XR_MODULE
            if (cameraData.xr.enabled)
            {
                cameraData.xr.StopSinglePass(cmd);
                cmd.DisableShaderKeyword(ShaderKeywordStrings.UseDrawProcedural);
                context.ExecuteCommandBuffer(cmd);
                cmd.Clear();
            }
#endif
        }

        internal static void SetRenderTarget(CommandBuffer cmd, RenderTargetIdentifier colorAttachment, RenderTargetIdentifier depthAttachment, ClearFlag clearFlag, Color clearColor)
        {
            m_ActiveColorAttachments[0] = colorAttachment;
            for (int i = 1; i < m_ActiveColorAttachments.Length; ++i)
                m_ActiveColorAttachments[i] = 0;

            m_ActiveDepthAttachment = depthAttachment;

            RenderBufferLoadAction colorLoadAction = ((uint)clearFlag & (uint)ClearFlag.Color) != 0 ?
                RenderBufferLoadAction.DontCare : RenderBufferLoadAction.Load;

            RenderBufferLoadAction depthLoadAction = ((uint)clearFlag & (uint)ClearFlag.Depth) != 0 ?
                RenderBufferLoadAction.DontCare : RenderBufferLoadAction.Load;

            SetRenderTarget(cmd, colorAttachment, colorLoadAction, RenderBufferStoreAction.Store,
                depthAttachment, depthLoadAction, RenderBufferStoreAction.Store, clearFlag, clearColor);
        }

        static void SetRenderTarget(
            CommandBuffer cmd,
            RenderTargetIdentifier colorAttachment,
            RenderBufferLoadAction colorLoadAction,
            RenderBufferStoreAction colorStoreAction,
            ClearFlag clearFlags,
            Color clearColor)
        {
            CoreUtils.SetRenderTarget(cmd, colorAttachment, colorLoadAction, colorStoreAction, clearFlags, clearColor);
        }

        static void SetRenderTarget(
            CommandBuffer cmd,
            RenderTargetIdentifier colorAttachment,
            RenderBufferLoadAction colorLoadAction,
            RenderBufferStoreAction colorStoreAction,
            RenderTargetIdentifier depthAttachment,
            RenderBufferLoadAction depthLoadAction,
            RenderBufferStoreAction depthStoreAction,
            ClearFlag clearFlags,
            Color clearColor)
        {
            // XRTODO: Revisit the logic. Why treat CameraTarget depth specially?
            if (depthAttachment == BuiltinRenderTextureType.CameraTarget)
            {
                SetRenderTarget(cmd, colorAttachment, colorLoadAction, colorStoreAction, clearFlags, clearColor);
            }
            else
            {
                CoreUtils.SetRenderTarget(cmd, colorAttachment, colorLoadAction, colorStoreAction,
                    depthAttachment, depthLoadAction, depthStoreAction, clearFlags, clearColor);
            }
        }

        static void SetRenderTarget(CommandBuffer cmd, RenderTargetIdentifier[] colorAttachments, RenderTargetIdentifier depthAttachment, ClearFlag clearFlag, Color clearColor)
        {
            m_ActiveColorAttachments = colorAttachments;
            m_ActiveDepthAttachment = depthAttachment;

            CoreUtils.SetRenderTarget(cmd, colorAttachments, depthAttachment, clearFlag, clearColor);
        }

        [Conditional("UNITY_EDITOR")]
        void DrawGizmos(ScriptableRenderContext context, Camera camera, GizmoSubset gizmoSubset)
        {
#if UNITY_EDITOR
            if (UnityEditor.Handles.ShouldRenderGizmos())
                context.DrawGizmos(camera, gizmoSubset);
#endif
        }

        [Conditional("UNITY_EDITOR")]
        void DrawWireOverlay(ScriptableRenderContext context, Camera camera)
        {
            context.DrawWireOverlay(camera);
        }

        void InternalStartRendering(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            CommandBuffer cmd = CommandBufferPool.Get();
            using (new ProfilingScope(cmd, Profiling.internalStartRendering))
            {
                for (int i = 0; i < m_ActiveRenderPassQueue.Count; ++i)
                {
                    m_ActiveRenderPassQueue[i].OnCameraSetup(cmd, ref renderingData);
                }
            }

            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }

        void InternalFinishRendering(ScriptableRenderContext context, bool resolveFinalTarget)
        {
            CommandBuffer cmd = CommandBufferPool.Get();
            using (new ProfilingScope(cmd, Profiling.internalFinishRendering))
            {
                for (int i = 0; i < m_ActiveRenderPassQueue.Count; ++i)
                    m_ActiveRenderPassQueue[i].FrameCleanup(cmd);

                // Happens when rendering the last camera in the camera stack.
                if (resolveFinalTarget)
                {
                    for (int i = 0; i < m_ActiveRenderPassQueue.Count; ++i)
                        m_ActiveRenderPassQueue[i].OnFinishCameraStackRendering(cmd);

                    FinishRendering(cmd);

                    // We finished camera stacking and released all intermediate pipeline textures.
                    m_IsPipelineExecuting = false;
                }
                m_ActiveRenderPassQueue.Clear();
            }

            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }

        internal static void SortStable(List<ScriptableRenderPass> list)
        {
            int j;
            for (int i = 1; i < list.Count; ++i)
            {
                ScriptableRenderPass curr = list[i];

                j = i - 1;
                for (; j >= 0 && curr < list[j]; --j)
                    list[j + 1] = list[j];

                list[j + 1] = curr;
            }
        }

        internal struct RenderBlocks : IDisposable
        {
            private NativeArray<RenderPassEvent> m_BlockEventLimits;
            private NativeArray<int> m_BlockRanges;
            private NativeArray<int> m_BlockRangeLengths;
            public RenderBlocks(List<ScriptableRenderPass> activeRenderPassQueue)
            {
                // Upper limits for each block. Each block will contains render passes with events below the limit.
                m_BlockEventLimits = new NativeArray<RenderPassEvent>(k_RenderPassBlockCount, Allocator.Temp);
                m_BlockRanges = new NativeArray<int>(m_BlockEventLimits.Length + 1, Allocator.Temp);
                m_BlockRangeLengths = new NativeArray<int>(m_BlockRanges.Length, Allocator.Temp);

                m_BlockEventLimits[RenderPassBlock.BeforeRendering] = RenderPassEvent.BeforeRenderingPrePasses;
                m_BlockEventLimits[RenderPassBlock.MainRenderingOpaque] = RenderPassEvent.AfterRenderingOpaques;
                m_BlockEventLimits[RenderPassBlock.MainRenderingTransparent] = RenderPassEvent.AfterRenderingPostProcessing;
                m_BlockEventLimits[RenderPassBlock.AfterRendering] = (RenderPassEvent)Int32.MaxValue;

                // blockRanges[0] is always 0
                // blockRanges[i] is the index of the first RenderPass found in m_ActiveRenderPassQueue that has a ScriptableRenderPass.renderPassEvent higher than blockEventLimits[i] (i.e, should be executed after blockEventLimits[i])
                // blockRanges[blockEventLimits.Length] is m_ActiveRenderPassQueue.Count
                FillBlockRanges(activeRenderPassQueue);
                m_BlockEventLimits.Dispose();

                for (int i = 0; i < m_BlockRanges.Length - 1; i++)
                {
                    m_BlockRangeLengths[i] = m_BlockRanges[i + 1] - m_BlockRanges[i];
                }
            }

            //  RAII like Dispose pattern implementation for 'using' keyword
            public void Dispose()
            {
                m_BlockRangeLengths.Dispose();
                m_BlockRanges.Dispose();
            }

            // Fill in render pass indices for each block. End index is startIndex + 1.
            void FillBlockRanges(List<ScriptableRenderPass> activeRenderPassQueue)
            {
                int currRangeIndex = 0;
                int currRenderPass = 0;
                m_BlockRanges[currRangeIndex++] = 0;

                // For each block, it finds the first render pass index that has an event
                // higher than the block limit.
                for (int i = 0; i < m_BlockEventLimits.Length - 1; ++i)
                {
                    while (currRenderPass < activeRenderPassQueue.Count &&
                           activeRenderPassQueue[currRenderPass].renderPassEvent < m_BlockEventLimits[i])
                        currRenderPass++;

                    m_BlockRanges[currRangeIndex++] = currRenderPass;
                }

                m_BlockRanges[currRangeIndex] = activeRenderPassQueue.Count;
            }

            public int GetLength(int index)
            {
                return m_BlockRangeLengths[index];
            }

            // Minimal foreach support
            public struct BlockRange : IDisposable
            {
                int m_Current;
                int m_End;
                public BlockRange(int begin, int end)
                {
                    Assertions.Assert.IsTrue(begin <= end);
                    m_Current = begin < end ? begin : end;
                    m_End   = end >= begin ? end : begin;
                    m_Current -= 1;
                }

                public BlockRange GetEnumerator() { return this; }
                public bool MoveNext() { return ++m_Current < m_End; }
                public int Current { get => m_Current; }
                public void Dispose() {}
            }

            public BlockRange GetRange(int index)
            {
                return new BlockRange(m_BlockRanges[index], m_BlockRanges[index + 1]);
            }
        }
    }
}