SampleRenderPasses/Assets/Scripts/RenderPasses/ScreenFadeFeature.cs

using Golems.RenderFeatures;
using UnityEngine;
using UnityEngine.Rendering;
using Golems.Attributes;
using RogueUtils.Data;
using UnityEngine.Rendering.Universal;
using static Golems.ScriptableRenderPassHelper;

namespace Golems
{
    public class ScreenFadeFeature : SourceToDestinationBlitRenderFeature
    {
        [Header("Screen fade things")]
        //
        // This is the fade colour used to fade the screen.
        // It is up to whatever is setting this to correctly set the alpha.
        //
        [SerializeField] 
        private ColorVariable m_TargetFadeColour = default;

        public bool IsEnabled
        {
            get
            {
                return m_IsEnabled;;
            }
            set
            {
                m_IsEnabled = value;
            }
        }
        
        [SerializeField] 
        private bool m_IsEnabled = false;


        private ScreenFadePass m_Pass = default;
        
        public override void Create()
        {
            m_Pass = new ScreenFadePass(m_TargetFadeColour);

            DoCreate();
            

        }

        private void DebugSetEnabledState(bool state)
        {
            m_IsEnabled = state;
        }
        private bool DebugGetEnabledState()
        {
            return m_IsEnabled;
        }
        
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            if (IsSourceAndDestinationSame() && !m_IsEnabled)
            {
                //
                // Can skip this pass as the source and destination are the same and the fade
                // is not enabled.
                //
                return;
            }

            m_Pass.Setup(m_IsEnabled, m_WhenToInsert, renderer.cameraColorTarget,
                m_SourceTextureSourceType, m_SourceNamedTemporaryNameHash,
                m_DestinationTextureSourceType, m_DestinationNamedTemporaryNameHash,
                m_TempCopyNamedTemporaryNameHash);
            renderer.EnqueuePass(m_Pass);
        }
    }

    public class ScreenFadePass : SourceToDestinationBlitRenderPass
    {
        private const string k_ProfilerIdent = "ScreenFadePass";
        private const string k_ScreenFaderCompositeShader = "Hidden/ScreenFaderComposite";
        private const string k_FadeColour = "_FadeColour";

        private static readonly int k_FadeColourId = Shader.PropertyToID(k_FadeColour);

        private Material m_ScreenFaderCompositeMaterial = default;

        private readonly Color m_FadeColour;

        private bool m_IsEnabled;
        
        public ScreenFadePass(ColorVariable colourVariable)
        {
            CreateMaterial(k_ScreenFaderCompositeShader, out m_ScreenFaderCompositeMaterial);
            m_FadeColour = Color.white;
        }
        
        public void Setup(bool isEnabled, RenderPassEvent whenToRender, RenderTargetIdentifier cameraColourTargetIdentifier,
            RenderFeatures.TextureSourceType sourceSourceType, int tempSourceTextureHash,
            RenderFeatures.TextureSourceType destinationSourceType, int tempDestinationTextureHash,
            int sameSourceDestTextureHash)
        {
            m_IsEnabled = isEnabled;
            DoSetup(whenToRender, cameraColourTargetIdentifier,
                sourceSourceType, tempSourceTextureHash,
                destinationSourceType, tempDestinationTextureHash,
                sameSourceDestTextureHash);
        }

        public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
        {
            DoOnCameraSetup(cmd, ref renderingData);
        }
        
        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
#if UNITY_EDITOR
            if (m_ScreenFaderCompositeMaterial == null)
            {
                //
                // In Editor the material will get destroyed on scene change
                //
                CreateMaterial(k_ScreenFaderCompositeShader, out m_ScreenFaderCompositeMaterial);
                if (m_ScreenFaderCompositeMaterial == null)
                {
                    return;
                }
            }
#endif
            if (!m_GoodToExecute)
            {
                return;
            }

            //
            // Set up all the shader parameters here! 
            //
            var fadeColour = m_FadeColour;

            bool doCopyOnly = fadeColour.a == 0.0f || !m_IsEnabled;
            if (doCopyOnly)
            {
                //
                // Nothing to blend
                //
                if (!m_SourceAndDestinationSame)
                {
                    //
                    // Copy the source to the destination
                    //
                    var copyCmd = CommandBufferPool.Get(k_ProfilerIdent);
                    copyCmd.Blit(m_SourceTargetIdentifier, m_DestinationTargetIdentifier);
                    context.ExecuteCommandBuffer(copyCmd);
                    CommandBufferPool.Release(copyCmd);
                }
                return;
            }
            m_ScreenFaderCompositeMaterial.SetColor(k_FadeColourId, fadeColour);

            var cmd = CommandBufferPool.Get(k_ProfilerIdent);
            
            if (m_SourceAndDestinationSame)
            {
                // Blit the Camera into the screen copy texture using the the fader shader
                cmd.Blit(m_SourceTargetIdentifier, m_TempCopyTargetIdentifier, m_ScreenFaderCompositeMaterial);
                // blit back into the camera texture
                cmd.Blit(m_TempCopyTargetIdentifier, m_DestinationTargetIdentifier);
            }
            else
            {
                cmd.Blit(m_SourceTargetIdentifier, m_DestinationTargetIdentifier, m_ScreenFaderCompositeMaterial);
            }
            
            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }
    }
}