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

public class FogRenderPassFeature : ScriptableRendererFeature
{
    public enum OutPutType { screen, rTexture, both }

    [System.Serializable]
    public class Setting
    {
        public RenderPassEvent renderPassEvent = RenderPassEvent.AfterRenderingTransparents;
        public Material materal;
        public OutPutType outPutType = OutPutType.screen;
        public RenderTexture outPutRt = null;
    }

    public Setting setting = new Setting();

    class FogRenderPass : ScriptableRenderPass
    {
        private Material material;
        private OutPutType outPutType;
        private RenderTexture outPutRt;
        private ProfilingSampler profilingSampler;
        private int tempTextureId = Shader.PropertyToID("_FogTempTexture");

        public FogRenderPass(FogRenderPassFeature.Setting setting)
        {
            renderPassEvent = setting.renderPassEvent;
            material = setting.materal;
            outPutType = setting.outPutType;
            outPutRt = setting.outPutRt;
            profilingSampler = new ProfilingSampler("FogRenderPassFeature");
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            if (renderingData.cameraData.isSceneViewCamera) return;
            if (material == null) return;

            CommandBuffer cmd = CommandBufferPool.Get();
            using (new ProfilingScope(cmd, profilingSampler))
            {
                // 不渲染UI Layer
                renderingData.cameraData.camera.cullingMask &= ~(1 << LayerMask.NameToLayer("UI"));

                // 创建临时渲染纹理描述符
                RenderTextureDescriptor descriptor = renderingData.cameraData.cameraTargetDescriptor;
                descriptor.depthBufferBits = 0;
                cmd.GetTemporaryRT(tempTextureId, descriptor);

                // 应用材质
                cmd.Blit(null, tempTextureId, material);

                switch (outPutType)
                {
                    case OutPutType.screen:
                        cmd.Blit(tempTextureId, BuiltinRenderTextureType.CameraTarget);
                        break;
                    case OutPutType.rTexture:
                        if (outPutRt != null)
                            cmd.Blit(tempTextureId, outPutRt);
                        break;
                    case OutPutType.both:
                        cmd.Blit(tempTextureId, BuiltinRenderTextureType.CameraTarget);
                        if (outPutRt != null)
                            cmd.Blit(tempTextureId, outPutRt);
                        break;
                }

                // 释放临时纹理
                cmd.ReleaseTemporaryRT(tempTextureId);
            }

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

    FogRenderPass fogRenderPass;

    public override void Create()
    {
        fogRenderPass = new FogRenderPass(setting);
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        renderer.EnqueuePass(fogRenderPass);
    }
}