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Unity URP 风格化水

时间:2023-12-27 17:46:59浏览次数:38  
标签:cmd MainTex int uv Unity xy URP 风格化 public

前言

笔者曾使用UE实现过一个较为完整的写实水材质系统,但是因为UE的管线是定死的,导致高光无法实现,且后来做笔试题发现关于水的交互还未实现,因此本文将实现一个完整的风格化水,考虑到水的实现部分过多,这里不再使用代码展示,而是使用ASE,原理都差不多

管线设置

  • “Shader Type” 为 “Universal/Unlit”
  • “Surface” 为 “Transparent”
  • “Vertex Position” 为 “Relative”

深度

  • 水深不必多讲,在UE的water shader中曾实现过,就是用scene depth - pixel depth

  • 实现如下
    这里需要根据相机的深度图重建世界坐标,请注意该方法会忽略半透明物体

颜色

有了深度就可以用深度来实现水的颜色了,这里会实现浅水、深水、海岸线、水底的颜色

浅水、深水

  • 思路:根据深度对浅水颜色和深水颜色进行lerp

  • 实现

HSV颜色空间

  • 因为人眼对灰颜色更加敏感,所以对RGB的lerp是不对的,而HSV空间可以解决这个问题

  • 实现

    • RGB转HSV

      half3 RGBToHSV(half3 In)
      {
          half4 K = half4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
          half4 P = lerp(half4(In.bg, K.wz), half4(In.gb, K.xy), step(In.b, In.g));
          half4 Q = lerp(half4(P.xyw, In.r), half4(In.r, P.yzx), step(P.x, In.r));
          half D = Q.x - min(Q.w, Q.y);
          half E = 1e-10;
          
          return half3(abs(Q.z + (Q.w - Q.y)/(6.0 * D + E)), D / (Q.x + E), Q.x);
      }
      
    • HSV转RGB

      half3 HSVToRGB(half3 In)
      {
          half4 K = half4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
          half3 P = abs(frac(In.xxx + K.xyz) * 6.0 - K.www);
          return In.z * lerp(K.xxx, saturate(P - K.xxx), In.y);
      }
      
    • 在HSV空间进行lerp

      half4 HSVLerp(half4 A, half4 B, half T)
      {
          half4 Out = 0.f;
          A.xyz = RGBToHSV(A.xyz);
          B.xyz = RGBToHSV(B.xyz);
      
          half t = T; // used to lerp alpha, needs to remain unchanged
      
          half hue;
          half d = B.x - A.x; // hue difference
      
          if(A.x > B.x)
          {
              half temp = B.x;
              B.x = A.x;
              A.x = temp;
      
              d = -d;
              T = 1-T;
          }
      
          if(d > 0.5)
          {
              A.x = A.x + 1;
              hue = (A.x + T * (B.x - A.x)) % 1;
          }
      
          if(d <= 0.5) hue = A.x + T * d;
      
          half sat = A.y + T * (B.y - A.y);
          half val = A.z + T * (B.z - A.z);
          half alpha = A.w + t * (B.w - A.w);
      
          half3 rgb = HSVToRGB(half3(hue,sat,val));
      
          Out = half4(rgb, alpha);
      
          return Out;
      }
      

海岸线

  • 海岸线是因为fresnel效应,导致水平看向水面的颜色肯定是不同的

  • 实现
    使用Fresnel即可

  • 效果

不透明度

  • 思路:根据深度控制opacity

  • 实现

表面涟漪

  • 思路:使用normal map来模拟凹凸感,为了防止涟漪看着太假,可以使用两张normal map最后进行blend即可

  • 实现

高光

  • 思路:Blinn-Phong

  • 实现


    Light Hardness用于控制高光的软硬程度,step计算结果是最硬的高光

  • 效果

折射

  • 思路:基于normalized screen space(uv : 0 - 1)进行扰动

  • 实现

  • 效果

反射

  • 因为平面反射使用一个摄像机从镜像角度渲染场景到RenderTexture上,再将结果合并至反射平面,开销不小,适用于PC端,这种方式实现的反射效果十分准确,但缺点是需要重新渲染一次场景,想想如果有多个镜面,那开销着实受不了,所以笔者选择使用对移动端友好的屏幕空间平面反射(ssrp),原理是在屏幕空间中计算镜面反射,开销很低,但效果不是很准确,只能反射屏幕中的像素,容易露馅。对于水面来说,ssrp足以

  • 实现

    1. 因为ssrp基于屏幕空间,可以将其看作一种后处理技术,Volume代码如下

      using UnityEngine;
      using UnityEngine.Rendering;
      
      namespace UnityEditor.Rendering.Universal
      {
          [SerializeField]
          public class SSPRVolume : VolumeComponent
          {
              [Tooltip("是否启用SSPR")]
              public BoolParameter m_Enable = new BoolParameter(false);
              
              [Tooltip("是否启用HDR")] 
              public BoolParameter m_EnableHDR = new BoolParameter(false);
              
              [Tooltip("反射平面分辨率")]
              public ClampedIntParameter m_RTSize = new ClampedIntParameter(512, 128, 1024, false);
              
              [Tooltip("反射平面深度")]
              public FloatParameter m_ReflectPlaneHeight = new FloatParameter(0.5f, false);
              
              [Tooltip("根据距离对屏幕边缘进行平滑")]
              public ClampedFloatParameter m_FadeOutEdge = new ClampedFloatParameter(0.5f, 0f, 1f, false);
      
              [Tooltip("控制分辨率")] 
              public ClampedIntParameter m_Downsample = new ClampedIntParameter(1, 1, 5);
      
              [Tooltip("模糊算法循环次数,越高效果越好")]
              public ClampedIntParameter m_PassLoop = new ClampedIntParameter(1, 1, 5);
      
              [Tooltip("模糊强度")] 
              public ClampedFloatParameter m_BlurIntensity = new ClampedFloatParameter(1, 0, 10);
              
              public bool IsActive() => m_Enable.value;
              public bool IsTileCompatible() => false;
          }
      }
      
    2. compute shader

      • 参数

        #define THREADCOUNTX 8
        #define THREADCOUNTY 8
        #define THREADCOUNTZ 1
        
        RWTexture2D<half4> _ResultRT;  // 反射后的RT
        RWTexture2D<half> _ResultDepthRT;  // 反射后的depth
        Texture2D<float4> _ScreenColorTex;    // scene color
        Texture2D<float4> _ScreenDepthTex;   // scene depth
        
        float2 _RTSize; // 反射后的RT分辨率
        float _ReflectPlaneHeight;  //  反射平面高度(基于screen space uv)
        float _FadeOutEdge; // 屏幕边缘的衰减程度
        float _BlurIntensity;   // DualBlur 模糊强度
        
        SamplerState PointClampSampler;    // 点采样
        SamplerState LinearClampSampler;   // 线性采样
        
      • 初始化

        将RT和Depth清0

        [numthreads(THREADCOUNTX, THREADCOUNTY, THREADCOUNTZ)]
        void ClearRT(uint3 id : SV_DispatchThreadID)
        {
            _ResultRT[id.xy] = half4(0.f, 0.f, 0.f, 0.f);
            _ResultDepthRT[id.xy] = half4(0.f, 0.f, 0.f, 0.f);
        }
        
      • SSRP计算

        • 重建世界坐标

          [numthreads(THREADCOUNTX, THREADCOUNTY, THREADCOUNTZ)]
          void CSMain (uint3 id : SV_DispatchThreadID)
          {
              float2 uvSS = id.xy / _RTSize;  // [0,RTSize-1] -> screen [0,1] uv
              
              float posNDCZ = _ScreenDepthTex.SampleLevel(PointClampSampler, uvSS, 0.f).r;    // raw depth
          
              float3 absoluteWolrdPos = ComputeWorldSpacePosition(uvSS, posNDCZ, UNITY_MATRIX_I_VP);  // 求得重建后的世界坐标
          }
          
        • 重建反射后的世界坐标

          if(absoluteWolrdPos.y < _ReflectPlaneHeight) return;    // 丢弃位于平面下方的像素
          float3 reflectPosWS = absoluteWolrdPos;
          reflectPosWS.y = -(reflectPosWS.y - _ReflectPlaneHeight) + _ReflectPlaneHeight; // 先将坐标减去_ReflectPlaneHeight,使其基于y = 0进行翻转(取负)
          

        • 构建并测试屏幕空间uv

          // 因为重建后的屏幕空间uv可以超出屏幕范围,需要进行测试
          float4 reflectPosCS = mul(UNITY_MATRIX_VP, float4(reflectPosWS, 1.f));   // posWS -> posCS
          float2 reflectPosNDCxy = reflectPosCS.xy / reflectPosCS.w;  // posCS -> posNDC
          if(abs(reflectPosNDCxy.x) > 1.f || abs(reflectPosNDCxy.y) > 1.f) return; // uv范围在[0,1]
          float2 reflectPosSSxy = reflectPosNDCxy * 0.5 + 0.5;	// ndc->ss
          
          // dx平台uv坐标起点在上方
          #if defined UNITY_UV_STARTS_AT_TOP
              reflectPosSSxy.y = 1 - reflectPosSSxy.y;
          #endif
          
          uint2 reflectSSUVID = reflectPosSSxy * _RTSize;  // 根据正确的屏幕uv计算得到新的thread id
          
        • 输出

          _ResultRT[reflectSSUVID] = float4(_ScreenColorTex.SampleLevel(LinearClampSampler, uvSS, 0).rgb, 1);
          

          可以看到这存在一定的遮挡问题(物体的反射渲染顺序错误)。如下图所示,造成这一现象的原因是两个不同的像素反射后都位于同一UV

        • 深度顺序矫正

          很显然,这里可以用到深度缓冲区,写入深度更小的像素(dx平台因为z值翻转,需要写入深度更大的像素)。这样会导致无法反射sky box,后续需要在PS中合并

          #if defined UNITY_REVERSED_Z
          if(reflectPosCS.z / reflectPosCS.w <= _ResultDepthRT[reflectSSUVID]) return;
          #else
          if(rePosCS.z / rePosCS.w >= _ResultDepthRT[reSSUVID]) return;
          #endif
              
          _ResultDepthRT[reflectSSUVID] = reflectPosCS.z / reflectPosCS.w;
          
        • 边缘缺失

          在某些视角下,若反射所需要的信息在渲染后的RT外,会生成不少空白像素,这里有两种解决办法:拉伸uv和2d sdf

          考虑到性能,笔者使用SDF。具体原理是:sdf 作为不透明度

          // 计算pixel到屏幕边缘的距离
          float SDF(float2 pos)
          {
              float2 distance = abs(pos) - float2(1, 1);
              return length(max(0.f, distance) - min(max(distance.x, distance.y), 0.f));
          }
          
          float mask = SDF(uvSS * 2.f - 1.f);
          mask = smoothstep(0.f, _FadeOutEdge, abs(mask));	// 做一个平滑,避免生硬
          _ResultRT[reflectSSUVID] = float4(_ScreenColorTex.SampleLevel(LinearClampSampler, uvSS, 0).rgb, mask);
          
        • 填充空洞

          如下图所示,反射后的平面会存在许多黑点空洞。这是因为计算世界坐标进行了透视投影的计算(近大远小),导致最后的像素索引进行了偏移(如本该渲染到(1,1)的,却渲染到(1,2))

          解决方法有两个:计算像素明度 和 根据像素的透明度,这里笔者选择透明度

          [numthreads(THREADCOUNTX, THREADCOUNTY, THREADCOUNTZ)]
          void FillHoles (uint3 id : SV_DispatchThreadID)
          {
              ////////////////////////////////
              // 
              ////////////////////////////////
              float4 center = _ResultRT[id.xy];
              float4 top = _ResultRT[id.xy + uint2(0, 1)];
              float4 bottom = _ResultRT[id.xy + uint2(0, -1)];
              float4 right = _ResultRT[id.xy + uint2(1, 0)];
              float4 left = _ResultRT[id.xy + uint2(-1, 0)];
              
              // 查找不是空洞的pixel
              float4 best = center;
              best = top.a > best.a + 0.5 ? top : best;
              best = bottom.a > best.a + 0.5 ? bottom : best;
              best = right.a > best.a + 0.5 ? right : best;
              best = left.a > best.a + 0.5 ? left : best;
              
              // 填充空洞
              _ResultRT[id.xy] = best.a > center.a + 0.5 ? best : center;
              _ResultRT[id.xy + uint2(0, 1)] = best.a > top.a + 0.5 ? best : top;
              _ResultRT[id.xy + uint2(0, -1)] = best.a > bottom.a + 0.5 ? best : bottom;
              _ResultRT[id.xy + uint2(1, 0)] = best.a > right.a + 0.5 ? best : right;
              _ResultRT[id.xy + uint2(-1, 0)] = best.a > left.a + 0.5 ? best : left;
          }
          

        • 闪烁

          没有找到好的解决方案,对于水体可以使用折射来遮羞

        • skybox 截断

          目前的实现还存在一个问题:当观察角度过于低时会绘制截断的skybox

          • 解决之道:跳过skybox

            void CSMain (uint3 id : SV_DispatchThreadID)
            {
                float2 uvSS = id.xy / _RTSize;  // [0,RTSize-1] -> screen [0,1] uv
                float posNDCZ = _ScreenDepthTex.SampleLevel(PointClampSampler, uvSS, 0.f).r;    // raw depth
                if(Linear01Depth(posNDCZ, _ZBufferParams) > 0.99) return; 
            }
            
            
    3. Render Feature

    反射是有一定的模糊效果的,这里使用Dual Blur

    using System;
    using UnityEngine;
    using UnityEngine.Rendering;
    using UnityEngine.Rendering.Universal;
    using UnityEditor.Rendering.Universal;
    
    public class SSPRPassFeature : ScriptableRendererFeature
    {
        [System.Serializable]
        public class PassSetting
        {
            [Tooltip("显示于frame debugger")]
            public readonly string m_ProfilerTag = "SSRP Pass";
            
            [Tooltip("Pass执行位置")]
            public RenderPassEvent passEvent = RenderPassEvent.AfterRenderingTransparents;
    
            [Tooltip("compute shader")]
            public ComputeShader CS = null;
    
            [Tooltip("Pixel Shader")]
            public Material material = null;
        }
        
        class SSPRRenderPass : ScriptableRenderPass
        {
            // profiler tag will show up in frame debugger
            private const string m_ProfilerTag = "SSPR Pass";
    
            // 用于存储pass setting
            private PassSetting m_passSetting;
            private SSPRVolume m_SSPRVolume;
    
            private ComputeShader m_CS;
            private Material m_Material;
            
            // 反射RT的分辨率
            private int RTSizeWidth;
            private int RTSizeHeight;
    
            struct RTID
            {
                public static RenderTargetIdentifier m_ResultRT;
                public static RenderTargetIdentifier m_ResultDepthRT;
                public static RenderTargetIdentifier m_TempRT;
            }
    
            struct ShaderID
            {
                public static readonly int RTSizeID = Shader.PropertyToID("_RTSize");
                public static readonly int ReflectPlaneHeightID = Shader.PropertyToID("_ReflectPlaneHeight");
                public static readonly int FadeOutEdgeID = Shader.PropertyToID("_FadeOutEdge");
                public static readonly int ReflectColorRTID = Shader.PropertyToID("_ResultRT");
                public static readonly int ResultDepthRTID = Shader.PropertyToID("_ResultDepthRT");
                public static readonly int SceneColorRTID = Shader.PropertyToID("_ScreenColorTex");
                public static readonly int SceneDepthRTID = Shader.PropertyToID("_ScreenDepthTex");
                
                public static readonly int BlurIntensityID = Shader.PropertyToID("_BlurIntensity");
                public static readonly int TempRTID = Shader.PropertyToID("_TempRT");
            }
            private struct BlurLevelShaderID
            {
                internal int downLevelID;
                internal int upLevelID;
            }
            private BlurLevelShaderID[] blurLevel;
            private static int m_maxBlurLevel = 16;
    
            struct Dispatch
            {
                // 线程组id
                public static int ThreadGroupCountX;
                public static int ThreadGroupCountY;
                public static int ThreadGroupCountZ;
                // 线程id
                public static int ThreadCountX;
                public static int ThreadCountY;
                public static int ThreadCountZ;
            }
    
            struct Kernal
            {
                public static int ClearRT;
                public static int CSMain;
                public static int FillHoles;
            }
            
            // 用于设置material 属性
            public SSPRRenderPass(SSPRPassFeature.PassSetting passSetting) 
            {
                this.m_passSetting = passSetting;
    
                renderPassEvent = m_passSetting.passEvent;
    
                this.m_CS = m_passSetting.CS;
                this.m_Material = m_passSetting.material;
    
                Kernal.ClearRT = m_CS.FindKernel("ClearRT");
                Kernal.CSMain = m_CS.FindKernel("CSMain");
                Kernal.FillHoles = m_CS.FindKernel("FillHoles");
            }
            
            public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
            {
                // 获取定义的volume
                var POSTStack = VolumeManager.instance.stack;
                m_SSPRVolume = POSTStack.GetComponent<SSPRVolume>();
    
                float aspect = (float)Screen.height / Screen.width;	// 屏幕分辨率
                // 线程对应compute shader中的线程数
                Dispatch.ThreadCountX = 8;
                Dispatch.ThreadCountY = 8;
                Dispatch.ThreadCountZ = 1;
                // 使得一个线程对应一个uv
                Dispatch.ThreadGroupCountY = m_SSPRVolume.m_RTSize.value / Dispatch.ThreadCountY;    // RT高度
                Dispatch.ThreadGroupCountX = Mathf.RoundToInt(Dispatch.ThreadGroupCountY / aspect); // RT 宽度
                Dispatch.ThreadGroupCountZ = 1;
                // 反射面的分辨率大小
                this.RTSizeWidth = Dispatch.ThreadGroupCountX * Dispatch.ThreadCountX;
                this.RTSizeHeight = Dispatch.ThreadGroupCountY * Dispatch.ThreadCountY;
                
                // alpha作为mask
                RenderTextureDescriptor descriptor = new RenderTextureDescriptor(this.RTSizeWidth, this.RTSizeHeight, RenderTextureFormat.ARGB32);
                if (m_SSPRVolume.m_EnableHDR.value == true)
                {
                    // 每位16字节,支持HDR
                    descriptor.colorFormat = RenderTextureFormat.ARGBHalf;
                }
                descriptor.enableRandomWrite = true;    // 用于D3D的UAV(无序视图)
                
                // 申请RT
                cmd.GetTemporaryRT(ShaderID.ReflectColorRTID, descriptor);
                RTID.m_ResultRT = new RenderTargetIdentifier(ShaderID.ReflectColorRTID);
                descriptor.colorFormat = RenderTextureFormat.R16;    // 深度图只有r channel
                cmd.GetTemporaryRT(ShaderID.ResultDepthRTID, descriptor);
                RTID.m_ResultDepthRT = new RenderTargetIdentifier(ShaderID.ResultDepthRTID);
    
                blurLevel = new BlurLevelShaderID[m_maxBlurLevel];
                for (int t = 0; t < m_maxBlurLevel; ++t)
                {
                    blurLevel[t] = new BlurLevelShaderID
                    {
                        downLevelID = Shader.PropertyToID("_BlurMipDown" + t),
                        upLevelID = Shader.PropertyToID("_BlurMipU" + t)
                    };
                }
            }
            
            public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
            {
                if (m_CS == null)
                {
                    Debug.LogError("Custom:SSPR compute shader missing");
                }
    
                if (m_SSPRVolume.m_Enable.value == true)
                {
                    // Grab a command buffer. We put the actual execution of the pass inside of a profiling scope
                    CommandBuffer cmd = CommandBufferPool.Get();
    
                    using (new ProfilingScope(cmd, new ProfilingSampler(m_ProfilerTag)))
                    {
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.ClearRT, ShaderID.ReflectColorRTID, RTID.m_ResultRT);
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.ClearRT, ShaderID.ResultDepthRTID, RTID.m_ResultDepthRT);
                        cmd.DispatchCompute(this.m_CS, Kernal.ClearRT, Dispatch.ThreadGroupCountX, Dispatch.ThreadGroupCountY, Dispatch.ThreadGroupCountZ);
                        
                        cmd.SetComputeVectorParam(this.m_CS, ShaderID.RTSizeID, new Vector2(this.RTSizeWidth, this.RTSizeHeight));
                        cmd.SetComputeFloatParam(this.m_CS, ShaderID.ReflectPlaneHeightID, m_SSPRVolume.m_ReflectPlaneHeight.value);
                        cmd.SetComputeFloatParam(this.m_CS, ShaderID.FadeOutEdgeID, m_SSPRVolume.m_FadeOutEdge.value);
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.CSMain, ShaderID.ReflectColorRTID, RTID.m_ResultRT);
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.CSMain, ShaderID.ResultDepthRTID, RTID.m_ResultDepthRT);
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.CSMain, ShaderID.SceneColorRTID, new RenderTargetIdentifier("_CameraOpaqueTexture"));
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.CSMain, ShaderID.SceneDepthRTID, new RenderTargetIdentifier("_CameraDepthTexture"));
                        cmd.DispatchCompute(this.m_CS, Kernal.CSMain, Dispatch.ThreadGroupCountX, Dispatch.ThreadGroupCountY, Dispatch.ThreadGroupCountZ);
                        
                        cmd.SetComputeTextureParam(this.m_CS, Kernal.FillHoles, ShaderID.ReflectColorRTID, RTID.m_ResultRT);
                        cmd.DispatchCompute(this.m_CS, Kernal.FillHoles, Dispatch.ThreadGroupCountX, Dispatch.ThreadGroupCountY, Dispatch.ThreadGroupCountZ);
                    }
    
                    if (m_Material == null)
                    {
                        Debug.LogError("Custom:SSPR shader missing");
                    }
                    else
                    {
                        m_Material.SetFloat(ShaderID.BlurIntensityID, m_SSPRVolume.m_BlurIntensity.value);
                        
                        RenderTextureDescriptor descriptor = new RenderTextureDescriptor(this.RTSizeWidth, this.RTSizeHeight, RenderTextureFormat.Default);
                        descriptor.width /= m_SSPRVolume.m_Downsample.value;
                        descriptor.height /= m_SSPRVolume.m_Downsample.value;
                        //descriptor.depthBufferBits = 0;     // 不会用到深度,精度设为0
                        cmd.GetTemporaryRT(ShaderID.TempRTID, descriptor);
                        RTID.m_TempRT = new RenderTargetIdentifier(ShaderID.TempRTID);
                        
                        Blit(cmd, RTID.m_ResultRT, RTID.m_TempRT);
                        
                        RenderTargetIdentifier lastDown = RTID.m_TempRT;
                        for (uint i = 0; i < m_SSPRVolume.m_PassLoop.value; ++i)
                        {
                            int midDown = blurLevel[i].downLevelID;
                            int midUp = blurLevel[i].upLevelID;
                            cmd.GetTemporaryRT(midDown, descriptor, FilterMode.Bilinear);
                            cmd.GetTemporaryRT(midUp, descriptor, FilterMode.Bilinear);
                            Blit(cmd, lastDown, midDown, m_Material, 1);
                            lastDown = midDown;
    
                            descriptor.width = Mathf.Max(descriptor.width / 2, 1);
                            descriptor.height = Mathf.Max(descriptor.height / 2, 1);
                        }
    
                        int lastUp = blurLevel[m_SSPRVolume.m_PassLoop.value - 1].downLevelID;
                        for (int i = m_SSPRVolume.m_PassLoop.value - 2; i >= 0; --i)
                        {
                            int midUp = blurLevel[i].upLevelID;
                            cmd.Blit(lastUp, midUp, m_Material, 2);
                            lastUp = midUp;
                        }
                        
                        cmd.Blit(lastUp, RTID.m_ResultRT, m_Material, 2);
                    }
                    context.ExecuteCommandBuffer(cmd);
                    CommandBufferPool.Release(cmd);
                }
            }
            
            public override void OnCameraCleanup(CommandBuffer cmd)
            {
                if(cmd == null) throw new ArgumentNullException("cmd");
                
                cmd.ReleaseTemporaryRT(ShaderID.ReflectColorRTID);
                cmd.ReleaseTemporaryRT(ShaderID.SceneDepthRTID);
            }
        }
    
        public PassSetting m_Setting = new PassSetting();
        SSPRRenderPass m_SSPRPass;
        
        public override void Create()
        {
            m_SSPRPass = new SSPRRenderPass(m_Setting);
        }
        
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            // can queue up multiple passes after each other
            renderer.EnqueuePass(m_SSPRPass);
        }
    }
    
    1. Shader

    最终效果还是得用material(pixel shader)实现(不过不用置于物体上)

    Shader "URP/reflect"
    {
        Properties
        {
            [HideInInspector] _MainTex("", 2D) = "white" {}
        }
    
        SubShader
        {
            Tags
            {
                "RenderPipeline"="UniversalRenderPipeline"
                "Queue"="Overlay"
            }
            Cull Off
            ZWrite Off
            ZTest Always
    
            HLSLINCLUDE
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
    
            CBUFFER_START(UnityPerMaterial)
            float _BlurIntensity;
            float4 _MainTex_TexelSize;
            CBUFFER_END
            
            TEXTURE2D(_MainTex);            SAMPLER(sampler_MainTex);
            TEXTURE2D(_ResultRT);
            sampler LinearClampSampler;
    
             struct VSInput
             {
                 float4 positionOS : POSITION;
                 float4 normalOS : NORMAL;
                 float2 uv : TEXCOORD;
             };
    
             struct PSInput
             {
                 float4 positionCS : SV_POSITION;
                 float2 uv:TEXCOORD;
                 float4 uv01 : TEXCOORD1;
                 float4 uv23 : TEXCOORD2;
                 float4 uv45 : TEXCOORD3;
                 float4 uv67 : TEXCOORD4;
                 float4 positionSS : TEXCOORD5;
                 float3 positionWS : TEXCOORD6;
                 float3 viewDirWS : TEXCOORD7;
                 float3 normalWS : NORMAL;
             };
            ENDHLSL
    
    
            pass
            {
                NAME "Copy SSRP"
                Tags
                {
                    "LightMode"="UniversalForward"
                    "RenderType"="Overlay"
                }
    
                HLSLPROGRAM
                #pragma vertex VS
                #pragma fragment PS
                
                PSInput VS(VSInput vsInput)
                {
                    PSInput vsOutput;
    
                    VertexPositionInputs vertexPos = GetVertexPositionInputs(vsInput.positionOS);
                    vsOutput.positionWS = vertexPos.positionWS;
                    vsOutput.positionCS = vertexPos.positionCS;
                    vsOutput.positionSS = ComputeScreenPos(vsOutput.positionCS);
    
                    VertexNormalInputs vertexNormal = GetVertexNormalInputs(vsInput.normalOS);
                    vsOutput.normalWS = vertexNormal.normalWS;
    
                    return vsOutput;
                }
    
                half4 PS(PSInput psInput) : SV_Target
                {
                    half2 screenUV = psInput.positionSS.xy / psInput.positionSS.w;
                    float4 SSPRResult = SAMPLE_TEXTURE2D(_ResultRT, LinearClampSampler, screenUV);
                    SSPRResult.xyz *= SSPRResult.w;
                    
                    return SSPRResult;
                }
                ENDHLSL
            }
    
            Pass
            {
                NAME "Down Samp[le"
                
                HLSLPROGRAM
                #pragma vertex VS
                #pragma fragment PS
    
                PSInput VS(VSInput vsInput)
                {
                    PSInput vsOutput;
    
                    vsOutput.positionCS = TransformObjectToHClip(vsInput.positionOS);
    
                    // 在D3D平台下,若开启抗锯齿,_TexelSize.y会变成负值,需要进行oneminus,否则会导致图像上下颠倒
                    #ifdef UNITY_UV_STARTS_AT_TOP
                    if(_MainTex_TexelSize.y < 0)
                        vsInput.uv.y = 1 - vsInput.uv.y;
                    #endif
                
                    vsOutput.uv = vsInput.uv;
                    vsOutput.uv01.xy = vsInput.uv + float2(1.f, 1.f) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv01.zw = vsInput.uv + float2(-1.f, -1.f) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv23.xy = vsInput.uv + float2(1.f, -1.f) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv23.zw = vsInput.uv + float2(-1.f, 1.f) * _MainTex_TexelSize.xy * _BlurIntensity;
    
                    return vsOutput;
                }
    
                float4 PS(PSInput psInput) : SV_TARGET
                {
                    float4 outputColor = 0.f;
    
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv.xy) * 0.5;
                    
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv01.xy) * 0.125;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv01.zw) * 0.125;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv23.xy) * 0.125;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv23.zw) * 0.125;
    
                    return outputColor;
                }
                
                ENDHLSL
            }
    
            Pass
            {
                NAME "Up Sample"
                
                HLSLPROGRAM
                #pragma vertex VS
                #pragma fragment PS
                
                PSInput VS(VSInput vsInput)
                {
                    PSInput vsOutput;
    
                    vsOutput.positionCS = TransformObjectToHClip(vsInput.positionOS);
    
                    #ifdef UNITY_UV_STARTS_AT_TOP
                    if(_MainTex_TexelSize.y < 0.f)
                        vsInput.uv.y = 1 - vsInput.uv.y;
                    #endif
    
                    vsOutput.uv = vsInput.uv;
                    // 1/12
                    vsOutput.uv01.xy = vsInput.uv + float2(0, 1) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv01.zw = vsInput.uv + float2(0, -1) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv23.xy = vsInput.uv + float2(1, 0) * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv23.zw = vsInput.uv + float2(-1, 0) * _MainTex_TexelSize.xy * _BlurIntensity;
                    // 1/6
                    vsOutput.uv45.xy = vsInput.uv + float2(1, 1) * 0.5 * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv45.zw = vsInput.uv + float2(-1, -1) * 0.5 * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv67.xy = vsInput.uv + float2(1, -1) * 0.5 * _MainTex_TexelSize.xy * _BlurIntensity;
                    vsOutput.uv67.zw = vsInput.uv + float2(-1, 1) * 0.5 * _MainTex_TexelSize.xy * _BlurIntensity;
    
                    return vsOutput;
                }
    
                float4 PS(PSInput psInput) : SV_TARGET
                {
                    float4 outputColor = 0.f;
    
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv01.xy) * 1/12;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv01.zw) * 1/12;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv23.xy) * 1/12;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv23.zw) * 1/12;
    
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv45.xy) * 1/6;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv45.zw) * 1/6;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv67.xy) * 1/6;
                    outputColor += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, psInput.uv67.zw) * 1/6;
    
                    return outputColor;
                }
                ENDHLSL
            }
        }
    } 
    

焦散

  • 思路:在UE中使用后处理实现过,这里尝试一种新方法,基于xz坐标绘制

  • 实现

    panner反向uv模拟焦散的运动

  • 纹理

  • 效果

浪花

  • 参考了很多游戏中的风格化水体效果,发现很少实现波峰浪花的,仅仅实现了近岸浪花,这里偷个懒也只实现近岸浪花叭

  • 实现
    FoamMask基于深度实现,使用Foam Cutoff来控制Foam区域

  • 效果

Wave

  • 老朋友了GerstnerWave,考虑到移动端的性能,最多叠加4个波

  • 实现

    float3 GerstnerWave(float3 positionWS, float steepness, float wavelength, float speed, float direction, inout float3 tangentWS, inout float3 binormalWS)
    {
        direction = direction * 2 - 1;
        float2 d = normalize(float2(cos(3.14 * direction), sin(3.14 * direction)));    
        float k = 2 * 3.14 / wavelength;   // 频率周期
        float f = k * (dot(d, positionWS.xz) - speed * _Time.y);   // sin/cos参数
        float a = steepness / k;   // 振幅(防止打结)
    
        tangentWS += float3(
        -d.x * d.x * (steepness * sin(f)),
        d.x * (steepness * cos(f)),
        -d.x * d.y * (steepness * sin(f))
        );
    
        binormalWS += float3(
        -d.x * d.y * (steepness * sin(f)),
        d.y * (steepness * cos(f)),
        -d.y * d.y * (steepness * sin(f))
        );
    
        return float3(
        d.x * (a * cos(f)),
        a * sin(f),
        d.y * (a * cos(f))
        );
    }
    
    float3 GerstnerWave4(float3 positionWS, float3 normalWS, float steepness, float waveLength, float speed, float4 direction)
    {
        float3 offset = 0.f;
        float3 tangent = float3(1, 0, 0);
        float3 binormal = float3(0, 0, 1);
    
        offset += GerstnerWave(positionWS, steepness, waveLength, speed, direction.x, tangent, binormal);
        offset += GerstnerWave(positionWS, steepness, waveLength, speed, direction.y, tangent, binormal);
        offset += GerstnerWave(positionWS, steepness, waveLength, speed, direction.z, tangent, binormal);
        offset += GerstnerWave(positionWS, steepness, waveLength, speed, direction.w, tangent, binormal);
    
        normalWS = cross(tangent, binormal);
        return offset;
    }
    

整合

最终效果

reference

Stylized Water Shader

The Secrets of Colour Interpolation

Simulating Waves Using The Water Waves Asset

https://zhuanlan.zhihu.com/p/357714920

UnityURP-MobileScreenSpacePlanarReflection

Unity URP实现屏幕空间平面反射(SSPR)

标签:cmd,MainTex,int,uv,Unity,xy,URP,风格化,public
From: https://www.cnblogs.com/chenglixue/p/17931028.html

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