using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.RendererUtils;
using UnityEngine.Rendering.Universal;
namespace Gameplay.PostProcess.BlackArea
{
    public class BlackAreaRPF : ScriptableRendererFeature
    {
        
        [System.Serializable]
        public class Settings
        {
            //渲染发生的阶段,具体信息可以在枚举类RenderPassEvent中查看
            public RenderPassEvent renderPassEvent = RenderPassEvent.BeforeRenderingPostProcessing;
            public LayerMask layerMask;
            public Material blitMaterial;
        }

        class CustomRenderPass : ScriptableRenderPass
        {

            private Settings _settings;
            private RenderTexture _cachedTarget;
            private readonly ShaderTagId _shaderTagId = new ShaderTagId("LightArea");
            
            private Material _blitMaterial;

            public CustomRenderPass(Settings settings)
            {
                _settings = settings;
                _blitMaterial = Instantiate(settings.blitMaterial);
            }

            public override void OnCameraSetup(CommandBuffer cmd,
                ref RenderingData renderingData)
            {
                base.OnCameraSetup(cmd, ref renderingData);
                // 只对主相机Camera.main生效
                if (renderingData.cameraData.camera != Camera.main) return;
                if (!BlackAreaManager.instance.enableBlackArea) return;
                // 创建一个RenderTexture
                _cachedTarget = RenderTexture.GetTemporary(renderingData.cameraData.camera.pixelWidth,
                    renderingData.cameraData.camera.pixelHeight, 32);
            }

            public override void OnCameraCleanup(CommandBuffer cmd)
            {
                base.OnCameraCleanup(cmd);
                if (_cachedTarget != null)
                {
                    RenderTexture.ReleaseTemporary(_cachedTarget);
                    _cachedTarget = null;
                }
            }

            public override void Execute(ScriptableRenderContext context,
                ref RenderingData renderingData)
            {
                // 只对主相机Camera.main生效
                if (renderingData.cameraData.camera != Camera.main) return;
                if (!BlackAreaManager.instance.enableBlackArea) return;
                var cmd = CommandBufferPool.Get("BlackArea-DrawMask");
                cmd.Clear();
                cmd.SetRenderTarget(_cachedTarget);
                // 刷一个黑色背景
                cmd.ClearRenderTarget(true, true, Color.black);
                // 渲染光亮区域
                var renderListDesc = new RendererListDesc(_shaderTagId, 
                    renderingData.cullResults, 
                    renderingData.cameraData.camera);
                renderListDesc.renderQueueRange = RenderQueueRange.all;
                renderListDesc.layerMask = _settings.layerMask;
                var renderList = context.CreateRendererList(renderListDesc);
                cmd.DrawRendererList(renderList);

                context.ExecuteCommandBuffer(cmd);
                CommandBufferPool.Release(cmd);
                
                // 把这张图渲染到屏幕上
                cmd = CommandBufferPool.Get("BlackArea-DrawMaskToScreen");
                var cameraRt = renderingData.cameraData.renderer.cameraColorTargetHandle.nameID;
                _blitMaterial.SetTexture(MaskTex, _cachedTarget);
                cmd.Blit(cameraRt, cameraRt, _blitMaterial);
                context.ExecuteCommandBuffer(cmd);
                CommandBufferPool.Release(cmd);
            }
        }

        public Settings settings;
        private CustomRenderPass _scriptablePass;
        private static readonly int MainTex = Shader.PropertyToID("_MainTex");
        private static readonly int MaskTex = Shader.PropertyToID("_MaskTex");

        public override void Create()
        {
            _scriptablePass = new CustomRenderPass(settings);
            _scriptablePass.renderPassEvent = settings.renderPassEvent;
        }
        
        public override void AddRenderPasses(ScriptableRenderer renderer,
            ref RenderingData renderingData)
        {
            renderer.EnqueuePass(_scriptablePass);
        }
    }
}