《Unity Shader 入门精要》从Bulit-in 到URP （HLSL ...

kirin77 · 发表于 2022-10-20 09:57

前言：

已经进入“高级篇”啦，希望大家多多支持，多多关注，这将对我产生非常愉悦的正反馈~

“《Unity Shader 入门精要》从Bulit-in 到URP”是一个帮助Unity Shader学习者以冯乐乐女神《Unity Shader 入门精要》为基础学习用HLSL语言编写URP着色器的案例教学系列。

作者自学能力有限，抛砖引玉，如有建议和问题请各位大佬和同仁交流指正。

如何在URP中实现后处理参见：

《Unity Shader 入门精要》从Bulit-in 到URP （HLSL）之后处理（Post-processing : RenderFeature + VolumeComponent）

Bulit-in版：

// Upgrade NOTE: replaced &#39;mul(UNITY_MATRIX_MVP,*)&#39; with &#39;UnityObjectToClipPos(*)&#39;

Shader &#34;Unity Shaders Book/Chapter 12/Gaussian Blur&#34; {
Properties {
_MainTex (&#34;Base (RGB)&#34;, 2D) = &#34;white&#34; {}
_BlurSize (&#34;Blur Size&#34;, Float) = 1.0
}
SubShader {
CGINCLUDE

#include &#34;UnityCG.cginc&#34;

sampler2D _MainTex;
half4 _MainTex_TexelSize;
float _BlurSize;

struct v2f {
float4 pos : SV_POSITION;
half2 uv[5]: TEXCOORD0;
};

v2f vertBlurVertical(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

half2 uv = v.texcoord;

o.uv[0] = uv;
o.uv[1] = uv + float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[2] = uv - float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[3] = uv + float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;
o.uv[4] = uv - float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;

return o;
}

v2f vertBlurHorizontal(appdata_img v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

half2 uv = v.texcoord;

o.uv[0] = uv;
o.uv[1] = uv + float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[2] = uv - float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[3] = uv + float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;
o.uv[4] = uv - float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;

return o;
}

fixed4 fragBlur(v2f i) : SV_Target {
float weight[3] = {0.4026, 0.2442, 0.0545};

fixed3 sum = tex2D(_MainTex, i.uv[0]).rgb * weight[0];

for (int it = 1; it < 3; it++) {
sum += tex2D(_MainTex, i.uv[it*2-1]).rgb * weight[it];
sum += tex2D(_MainTex, i.uv[it*2]).rgb * weight[it];
}

return fixed4(sum, 1.0);
}

ENDCG

ZTest Always Cull Off ZWrite Off

Pass {
NAME &#34;GAUSSIAN_BLUR_VERTICAL&#34;

CGPROGRAM

#pragma vertex vertBlurVertical
#pragma fragment fragBlur

ENDCG
}

Pass {
NAME &#34;GAUSSIAN_BLUR_HORIZONTAL&#34;

CGPROGRAM

#pragma vertex vertBlurHorizontal
#pragma fragment fragBlur

ENDCG
}
}
FallBack &#34;Diffuse&#34;
}

URP版：

Shader &#34;Unlit/Chapter12-GaussianBlur&#34;
{
Properties {
_MainTex (&#34;Base (RGB)&#34;, 2D) = &#34;white&#34; {}
_BlurSize (&#34;Blur Size&#34;, Float) = 1.0
}
SubShader
{
      Tags { &#34;RenderPipeline&#34; = &#34;UniversalPipeline&#34; }

      HLSLINCLUDE
      #include &#34;Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl&#34;
#include &#34;Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl&#34;

      CBUFFER_START(UnityPerMaterial)
         half4 _MainTex_TexelSize;
      float _BlurSize;
      CBUFFER_END

      TEXTURE2D(_MainTex);    SAMPLER(sampler_MainTex);

      struct appdata{
         float4 vertex : POSITION;
         float2 texcoord : TEXCOORD0;
      };

      struct v2f {
float4 pos : SV_POSITION;
half2 uv[5] : TEXCOORD0;
      };

v2f vertBlurVertical(appdata v) {
v2f o;
o.pos = TransformObjectToHClip(v.vertex);

half2 uv = v.texcoord;

o.uv[0] = uv;
o.uv[1] = uv + float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[2] = uv - float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSize;
o.uv[3] = uv + float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;
o.uv[4] = uv - float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSize;
         //和属性_BlurSize相乘来控制采样距离。在高斯核维数不变的情况下，_BlurSize越大，模糊程度越高

return o;
}

v2f vertBlurHorizontal(appdata v) {
v2f o;
o.pos = TransformObjectToHClip(v.vertex);

half2 uv = v.texcoord;

o.uv[0] = uv;
o.uv[1] = uv + float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[2] = uv - float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSize;
o.uv[3] = uv + float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;
o.uv[4] = uv - float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSize;

return o;
}

half4 fragBlur(v2f i) : SV_Target {
float weight[3] = {0.4026, 0.2442, 0.0545};
         //高斯权重

half3 sum = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv[0]).rgb * weight[0];

for (int it = 1; it < 3; it++) {
sum += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv[it*2-1]).rgb * weight[it];
sum += SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv[it*2]).rgb * weight[it];
}

return half4(sum, 1.0);
}

ENDHLSL

ZTest Always Cull Off ZWrite Off

Pass {
NAME &#34;GAUSSIAN_BLUR_VERTICAL&#34;

HLSLPROGRAM

#pragma vertex vertBlurVertical
#pragma fragment fragBlur

ENDHLSL
}

Pass {
NAME &#34;GAUSSIAN_BLUR_HORIZONTAL&#34;

HLSLPROGRAM

#pragma vertex vertBlurHorizontal
#pragma fragment fragBlur

ENDHLSL
}
}
FallBack &#34;Packages/com.unity.render-pipelines.universal/FallbackError&#34;
}
URP后处理脚本

因为和上面提供的（Post-processing : RenderFeature + VolumeComponent）模板有些许差异（降采样、两个Pass分别渲染、迭代处理），因此在此提供对应源码。
using System;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

public class GaussianBlur : ScriptableRendererFeature
{
[Serializable, VolumeComponentMenu(&#34;Ding Post-processing/12.4 GaussianBlur&#34;)]
public class CustomVolumeComponent : DingVolumeComponentBase
{
      public ClampedFloatParameter BlurSpread = new ClampedFloatParameter(0.5f, 0.1f, 3f);
      public ClampedIntParameter Iterations = new ClampedIntParameter(3, 1, 4);
      public ClampedIntParameter DownSample = new ClampedIntParameter(2, 1, 8);

      public override bool IsActive() => isRender.value;
      public override bool IsTileCompatible() => false;

}

class CustomRenderPass : ScriptableRenderPass
{

      public Material material;
      //RT的滤波模式
      public FilterMode filterMode {get; set;}
      //当前渲染阶段的colorRT
      //RenderTargetIdentifier、RenderTargetHandle都可以理解为RT，Identifier为camera提供的需要被应用的texture，Handle为被shader处理渲染过的RT
      private RenderTargetIdentifier source {get; set;}
      private RenderTargetHandle destination {get; set;}
      //辅助RT
      private RenderTargetHandle tempTexture0;
      private RenderTargetHandle tempTexture1;
      string m_ProfilerTag;
      //Profiling上显示
      public CustomVolumeComponent volume;
      ProfilingSampler m_ProfilingSampler = new ProfilingSampler(&#34;URPDing&#34;);

      public CustomRenderPass(RenderPassEvent renderPassEvent, Shader shader, CustomVolumeComponent volume, string tag){
         //确定在哪个阶段插入渲染
         this.renderPassEvent = renderPassEvent;
         this.volume = volume;
         if(shader == null){return;}
         this.material = CoreUtils.CreateEngineMaterial(shader);
         m_ProfilerTag = tag;
         //初始化辅助RT的名字
         tempTexture0.Init(&#34;_TempRTexture0&#34;);
         tempTexture1.Init(&#34;_TempRTexture1&#34;);
      }

      public void Setup(RenderTargetIdentifier source, RenderTargetHandle destination){
         this.source = source;
         this.destination = destination;
      }

      public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
      {
         if (!volume.IsActive()) {
            return;
         }
         CommandBuffer cmd = CommandBufferPool.Get(&#34;m_ProfilerTag&#34;);
         //using 方法可以实现在FrameDebug上查看渲染过程
         using(new ProfilingScope(cmd, m_ProfilingSampler)){

            ref var cameraData = ref renderingData.cameraData;
            int w = cameraData.camera.scaledPixelWidth / volume.DownSample.value;
            int h = cameraData.camera.scaledPixelHeight / volume.DownSample.value;

            cmd.GetTemporaryRT(tempTexture0.id, w, h, 0, filterMode);
            Blit(cmd, source, tempTexture0.Identifier());

            for(int i = 0; i < volume.Iterations.value; i++){
                  material.SetFloat(&#34;_BlurSize&#34;, 1.0f + i * volume.BlurSpread.value);
                  cmd.GetTemporaryRT(tempTexture1.id, w, h, 0, filterMode);
                  Blit(cmd, tempTexture0.Identifier(), tempTexture1.Identifier(), material, 0);
                  cmd.ReleaseTemporaryRT(tempTexture0.id);
                  tempTexture0 = tempTexture1;
                  cmd.GetTemporaryRT(tempTexture1.id, w, h, 0, filterMode);
                  Blit(cmd, tempTexture0.Identifier(), tempTexture1.Identifier(), material, 1);
                  cmd.ReleaseTemporaryRT(tempTexture0.id);
                  tempTexture0 = tempTexture1;
            }

            Blit(cmd, tempTexture0.Identifier(), source);

         }
         //执行渲染
         context.ExecuteCommandBuffer(cmd);
         //释放回收
         CommandBufferPool.Release(cmd);
      }

      public override void FrameCleanup(CommandBuffer cmd){
         base.FrameCleanup(cmd);
         cmd.ReleaseTemporaryRT(tempTexture0.id);
         cmd.ReleaseTemporaryRT(tempTexture1.id);
      }
}

[System.Serializable]
public class Settings{
      public RenderPassEvent Event = RenderPassEvent.AfterRenderingTransparents;
      public Shader shader;
}

public Settings settings = new Settings();
CustomVolumeComponent volume;
CustomRenderPass m_ScriptablePass;

/// <inheritdoc/>
//feature被创建时调用
public override void Create()
{
      var stack = VolumeManager.instance.stack;
      volume = stack.GetComponent<CustomVolumeComponent>();
      if (volume == null) {
         CoreUtils.Destroy(m_ScriptablePass.material);
         return;
      }
      m_ScriptablePass = new CustomRenderPass(settings.Event, settings.shader, volume, name);
}

// Here you can inject one or multiple render passes in the renderer.
// This method is called when setting up the renderer once per-camera.
//每一帧都会调用
public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
{
      var src = renderer.cameraColorTarget;
      var dest = RenderTargetHandle.CameraTarget;

      if(settings.shader == null){
         Debug.LogWarningFormat(&#34;shader丢失&#34;,GetType().Name);
         return;
      }

      //将当前渲染的colorRT传到Pass中

      m_ScriptablePass.Setup(src, dest);

      //将Pass添加到渲染队列中
      renderer.EnqueuePass(m_ScriptablePass);
}

protected override void Dispose(bool disposing)
{
      base.Dispose(disposing);

}
}

效果图：

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