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StandardSurface shader 基础学习（一）

开启此篇章的原因： 现在都已经更新到 URP了，并且日常工作中也不会使用到Standard shader（工作中的shader都是自己人写的），之前了解过，也翻看过基本的standard shader 代码逻辑（尤其是PBR相关）。。。。

(1)之前在B站听大佬说：我认识的TA大佬，都把unity 内置的shader源码搂过一遍了。。。。。。 于是乎 我也想跟随大佬的脚步，认认真真的学习整理一遍，加深自己的记忆，也为以后忘记 迅速查找留下痕迹。。。

（2）最近由于工作需要，美术同学使用ASE 使用standard shader 连线做的shader… 需要翻译为普通的vf shader，。。。。。。于是乎，开启此系列：

此篇记录standardSurface shader 的基本结构
以及将standardSurface(后面简称 surface shader) 生成普通的vert frag shader (后面简称 vf shader)的代码：

在代码中有基本的结构注释，从 surface shader中声明的函数， 对应到 生成的 vf shader中的调用，体会达到的目的，更加深入的理解surface shader。

Shader "Custom/SurfaceShader01" {
	Properties {
		_Color ("Color", Color) = (1,1,1,1)
		_MainTex ("Albedo (RGB)", 2D) = "white" {}
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200

		CGPROGRAM
		
		//
		// vertex: vert  第一步
		// vert  在顶点着色器中调用： 负责初始化一个 v2f_surf 的结构体

		// surf  第二步
		// 对传递进来的描述物体外表面材质属性信息的 SurfaceOutput结构体进行赋值 ，并且返回


		// BasicDiffuse  第三步
		//  在第二步的处理后，  用第二步的表面片元信息， 用BasicDiffuse 进行光照计算

		// final  第四步
		// 在最后的颜色输出之前， 对颜色进行自定义的修改，按照final 函数进行处理，并且输出返回	

		#pragma surface surf BasicDiffuse vertex:vert finalcolor: final noforwardadd
		#pragma target 3.0

		sampler2D _MainTex;
		float4 _Color;

		struct Input {
			float2 uv_MainTex;
		};
		void vert(inout appdata_full v,out Input o)
		{
			o.uv_MainTex = v.texcoord.xy;
		}


		//  下面两行是GPU Instance 所需要的声明 ，现在可以忽略删除
		// Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
		// See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
		// #pragma instancing_options assumeuniformscaling
		UNITY_INSTANCING_BUFFER_START(Props)
			// put more per-instance properties here
		// 声明改顶点是否位于视线域内，来判断这个顶点是否需要输出到frag中
		UNITY_INSTANCING_BUFFER_END(Props)


		void surf (Input IN, inout SurfaceOutput o) {
			// 只用最简单的颜色输出
			fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}


		//  此处的 LightingBasicDiffuse  函数的名字由两部分组成： Lighting + BasicDiffuse  
		//   BasicDiffuse  即为上面#pragma中声明的的函数
		inline float4 LightingBasicDiffuse(SurfaceOutput s,fixed3 lightDir,fixed atten)
		{
			float diffuse_term = saturate(dot(s.Normal,lightDir));
			float4 col;
			col.rgb = s.Albedo.rgb * _LightColor0.rgb * diffuse_term;
			col.a = s.Alpha;
			return col;
		}

		void final(Input IN,SurfaceOutput o,inout fixed4 color)
		{
			color = fixed4(0,1,0,1);	
		}
		ENDCG
	}
	FallBack "Diffuse"
}

在点击“show generated code” 查看vf shader 生成的具体代码：
查找上面声明函数的对应关系和具体实现的效果！！！！！
在这里插入图片描述

Shader "Custom/SurfaceShader01" {
	Properties {
		_Color ("Color", Color) = (1,1,1,1)
		_MainTex ("Albedo (RGB)", 2D) = "white" {}
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200

		
	// ------------------------------------------------------------
	// Surface shader code generated out of a CGPROGRAM block:
	

	// ---- forward rendering base pass:
	Pass {
		Name "FORWARD"
		Tags { "LightMode" = "ForwardBase" }

CGPROGRAM
// compile directives
#pragma vertex vert_surf
#pragma fragment frag_surf
#pragma target 3.0
#pragma multi_compile_instancing
#pragma multi_compile_fog
#pragma multi_compile_fwdbase
#include "HLSLSupport.cginc"
#include "UnityShaderVariables.cginc"
#include "UnityShaderUtilities.cginc"
// -------- variant for: <when no other keywords are defined>
#if !defined(INSTANCING_ON)
// Surface shader code generated based on:
// vertex modifier: 'vert'
// writes to per-pixel normal: no
// writes to emission: no
// writes to occlusion: no
// needs world space reflection vector: no
// needs world space normal vector: no
// needs screen space position: no
// needs world space position: no
// needs view direction: no
// needs world space view direction: no
// needs world space position for lighting: no
// needs world space view direction for lighting: no
// needs world space view direction for lightmaps: no
// needs vertex color: no
// needs VFACE: no
// passes tangent-to-world matrix to pixel shader: no
// reads from normal: no
// 1 texcoords actually used
//   float2 _MainTex
#define UNITY_PASS_FORWARDBASE
#include "UnityCG.cginc"
#include "Lighting.cginc"
#include "AutoLight.cginc"

#define INTERNAL_DATA
#define WorldReflectionVector(data,normal) data.worldRefl
#define WorldNormalVector(data,normal) normal

// Original surface shader snippet:
#line 8 ""
#ifdef DUMMY_PREPROCESSOR_TO_WORK_AROUND_HLSL_COMPILER_LINE_HANDLING
#endif
/* UNITY: Original start of shader */
		
		//
		// vertex: vert  第一步
		// vert  在顶点着色器中调用： 负责初始化一个 v2f_surf 的结构体

		// surf  第二步
		// 对传递进来的描述物体外表面材质属性信息的 SurfaceOutput结构体进行赋值 ，并且返回


		// BasicDiffuse  第三步
		//  在第二步的处理后，  用第二步的表面片元信息， 用BasicDiffuse 进行光照计算

		// final  第四步
		// 在最后的颜色输出之前， 对颜色进行自定义的修改，按照final 函数进行处理，并且输出返回	

		//#pragma surface surf BasicDiffuse vertex:vert finalcolor: final noforwardadd
		//#pragma target 3.0

		sampler2D _MainTex;
		float4 _Color;

		struct Input {
			float2 uv_MainTex;
		};
		void vert(inout appdata_full v,out Input o)
		{
			o.uv_MainTex = v.texcoord.xy;
		}


		//  下面两行是GPU Instance 所需要的声明 ，现在可以忽略删除
		// Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
		// See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
		// //#pragma instancing_options assumeuniformscaling
		UNITY_INSTANCING_BUFFER_START(Props)
			// put more per-instance properties here
		// 声明改顶点是否位于视线域内，来判断这个顶点是否需要输出到frag中
		UNITY_INSTANCING_BUFFER_END(Props)


		void surf (Input IN, inout SurfaceOutput o) {
			// 只用最简单的颜色输出
			fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}


		//  此处的 LightingBasicDiffuse  函数的名字由两部分组成： Lighting + BasicDiffuse  
		//   BasicDiffuse  即为上面#pragma中声明的的函数
		inline float4 LightingBasicDiffuse(SurfaceOutput s,fixed3 lightDir,fixed atten)
		{
			float diffuse_term = saturate(dot(s.Normal,lightDir));
			float4 col;
			col.rgb = s.Albedo.rgb * _LightColor0.rgb * diffuse_term;
			col.a = s.Alpha;
			return col;
		}

		void final(Input IN,SurfaceOutput o,inout fixed4 color)
		{
			color = fixed4(0,1,0,1);	
		}
		

// vertex-to-fragment interpolation data
// no lightmaps:
#ifndef LIGHTMAP_ON
struct v2f_surf {
  UNITY_POSITION(pos);
  float2 pack0 : TEXCOORD0; // _MainTex
  float3 worldNormal : TEXCOORD1;
  float3 worldPos : TEXCOORD2;
  fixed3 vlight : TEXCOORD3; // ambient/SH/vertexlights
  UNITY_SHADOW_COORDS(4)
  UNITY_FOG_COORDS(5)
  #if SHADER_TARGET >= 30
  float4 lmap : TEXCOORD6;
  #endif
  UNITY_VERTEX_INPUT_INSTANCE_ID
  UNITY_VERTEX_OUTPUT_STEREO
};
#endif
// with lightmaps:
#ifdef LIGHTMAP_ON
struct v2f_surf {
  UNITY_POSITION(pos);
  float2 pack0 : TEXCOORD0; // _MainTex
  float3 worldNormal : TEXCOORD1;
  float3 worldPos : TEXCOORD2;
  float4 lmap : TEXCOORD3;
  UNITY_SHADOW_COORDS(4)
  UNITY_FOG_COORDS(5)
  #ifdef DIRLIGHTMAP_COMBINED
  float3 tSpace0 : TEXCOORD6;
  float3 tSpace1 : TEXCOORD7;
  float3 tSpace2 : TEXCOORD8;
  #endif
  UNITY_VERTEX_INPUT_INSTANCE_ID
  UNITY_VERTEX_OUTPUT_STEREO
};
#endif
float4 _MainTex_ST;

// vertex shader
v2f_surf vert_surf (appdata_full v) {
  UNITY_SETUP_INSTANCE_ID(v);
  v2f_surf o;
  UNITY_INITIALIZE_OUTPUT(v2f_surf,o);
  UNITY_TRANSFER_INSTANCE_ID(v,o);
  UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
  Input customInputData;
  vert (v, customInputData);
  o.pos = UnityObjectToClipPos(v.vertex);
  o.pack0.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
  float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
  float3 worldNormal = UnityObjectToWorldNormal(v.normal);
  #if defined(LIGHTMAP_ON) && defined(DIRLIGHTMAP_COMBINED)
  fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
  fixed tangentSign = v.tangent.w * unity_WorldTransformParams.w;
  fixed3 worldBinormal = cross(worldNormal, worldTangent) * tangentSign;
  #endif
  #if defined(LIGHTMAP_ON) && defined(DIRLIGHTMAP_COMBINED)
  o.tSpace0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
  o.tSpace1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
  o.tSpace2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
  #endif
  o.worldPos = worldPos;
  o.worldNormal = worldNormal;
  #ifdef DYNAMICLIGHTMAP_ON
  o.lmap.zw = v.texcoord2.xy * unity_DynamicLightmapST.xy + unity_DynamicLightmapST.zw;
  #endif
  #ifdef LIGHTMAP_ON
  o.lmap.xy = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
  #endif

  // SH/ambient and vertex lights
  #ifndef LIGHTMAP_ON
  #if UNITY_SHOULD_SAMPLE_SH && !UNITY_SAMPLE_FULL_SH_PER_PIXEL
  float3 shlight = ShadeSH9 (float4(worldNormal,1.0));
  o.vlight = shlight;
  #else
  o.vlight = 0.0;
  #endif
  #ifdef VERTEXLIGHT_ON
  o.vlight += Shade4PointLights (
    unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0,
    unity_LightColor[0].rgb, unity_LightColor[1].rgb, unity_LightColor[2].rgb, unity_LightColor[3].rgb,
    unity_4LightAtten0, worldPos, worldNormal );
  #endif // VERTEXLIGHT_ON
  #endif // !LIGHTMAP_ON

  UNITY_TRANSFER_SHADOW(o,v.texcoord1.xy); // pass shadow coordinates to pixel shader
  UNITY_TRANSFER_FOG(o,o.pos); // pass fog coordinates to pixel shader
  return o;
}

// fragment shader
fixed4 frag_surf (v2f_surf IN) : SV_Target {
  UNITY_SETUP_INSTANCE_ID(IN);
  // prepare and unpack data
  Input surfIN;
  UNITY_INITIALIZE_OUTPUT(Input,surfIN);
  surfIN.uv_MainTex.x = 1.0;
  surfIN.uv_MainTex = IN.pack0.xy;
  float3 worldPos = IN.worldPos;
  #ifndef USING_DIRECTIONAL_LIGHT
    fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
  #else
    fixed3 lightDir = _WorldSpaceLightPos0.xyz;
  #endif
  #ifdef UNITY_COMPILER_HLSL
  SurfaceOutput o = (SurfaceOutput)0;
  #else
  SurfaceOutput o;
  #endif
  o.Albedo = 0.0;
  o.Emission = 0.0;
  o.Specular = 0.0;
  o.Alpha = 0.0;
  o.Gloss = 0.0;
  fixed3 normalWorldVertex = fixed3(0,0,1);
  o.Normal = IN.worldNormal;
  normalWorldVertex = IN.worldNormal;

  // call surface function
  surf (surfIN, o);

  // compute lighting & shadowing factor
  UNITY_LIGHT_ATTENUATION(atten, IN, worldPos)
  fixed4 c = 0;
  #ifndef LIGHTMAP_ON
  c.rgb += o.Albedo * IN.vlight;
  #endif // !LIGHTMAP_ON

  // lightmaps
  #ifdef LIGHTMAP_ON
    #if DIRLIGHTMAP_COMBINED
      // directional lightmaps
      fixed4 lmtex = UNITY_SAMPLE_TEX2D(unity_Lightmap, IN.lmap.xy);
      half3 lm = DecodeLightmap(lmtex);
    #else
      // single lightmap
      fixed4 lmtex = UNITY_SAMPLE_TEX2D(unity_Lightmap, IN.lmap.xy);
      fixed3 lm = DecodeLightmap (lmtex);
    #endif

  #endif // LIGHTMAP_ON


  // realtime lighting: call lighting function
  #ifndef LIGHTMAP_ON
  c += LightingBasicDiffuse (o, lightDir, atten);
  #else
    c.a = o.Alpha;
  #endif

  #ifdef LIGHTMAP_ON
    // combine lightmaps with realtime shadows
    #ifdef SHADOWS_SCREEN
      #if defined(UNITY_NO_RGBM)
      c.rgb += o.Albedo * min(lm, atten*2);
      #else
      c.rgb += o.Albedo * max(min(lm,(atten*2)*lmtex.rgb), lm*atten);
      #endif
    #else // SHADOWS_SCREEN
      c.rgb += o.Albedo * lm;
    #endif // SHADOWS_SCREEN
  #endif // LIGHTMAP_ON

  #ifdef DYNAMICLIGHTMAP_ON
  fixed4 dynlmtex = UNITY_SAMPLE_TEX2D(unity_DynamicLightmap, IN.lmap.zw);
  c.rgb += o.Albedo * DecodeRealtimeLightmap (dynlmtex);
  #endif

  UNITY_APPLY_FOG(IN.fogCoord, c); // apply fog
  UNITY_OPAQUE_ALPHA(c.a);
  return c;
}


#endif

// -------- variant for: INSTANCING_ON 
#if defined(INSTANCING_ON)
// Surface shader code generated based on:
// vertex modifier: 'vert'
// writes to per-pixel normal: no
// writes to emission: no
// writes to occlusion: no
// needs world space reflection vector: no
// needs world space normal vector: no
// needs screen space position: no
// needs world space position: no
// needs view direction: no
// needs world space view direction: no
// needs world space position for lighting: no
// needs world space view direction for lighting: no
// needs world space view direction for lightmaps: no
// needs vertex color: no
// needs VFACE: no
// passes tangent-to-world matrix to pixel shader: no
// reads from normal: no
// 1 texcoords actually used
//   float2 _MainTex
#define UNITY_PASS_FORWARDBASE
#include "UnityCG.cginc"
#include "Lighting.cginc"
#include "AutoLight.cginc"

#define INTERNAL_DATA
#define WorldReflectionVector(data,normal) data.worldRefl
#define WorldNormalVector(data,normal) normal

// Original surface shader snippet:
#line 8 ""
#ifdef DUMMY_PREPROCESSOR_TO_WORK_AROUND_HLSL_COMPILER_LINE_HANDLING
#endif
/* UNITY: Original start of shader */
		
		//
		// vertex: vert  第一步
		// vert  在顶点着色器中调用： 负责初始化一个 v2f_surf 的结构体

		// surf  第二步
		// 对传递进来的描述物体外表面材质属性信息的 SurfaceOutput结构体进行赋值 ，并且返回


		// BasicDiffuse  第三步
		//  在第二步的处理后，  用第二步的表面片元信息， 用BasicDiffuse 进行光照计算

		// final  第四步
		// 在最后的颜色输出之前， 对颜色进行自定义的修改，按照final 函数进行处理，并且输出返回	

		//#pragma surface surf BasicDiffuse vertex:vert finalcolor: final noforwardadd
		//#pragma target 3.0

		sampler2D _MainTex;
		float4 _Color;

		struct Input {
			float2 uv_MainTex;
		};
		void vert(inout appdata_full v,out Input o)
		{
			o.uv_MainTex = v.texcoord.xy;
		}


		//  下面两行是GPU Instance 所需要的声明 ，现在可以忽略删除
		// Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
		// See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
		// //#pragma instancing_options assumeuniformscaling
		UNITY_INSTANCING_BUFFER_START(Props)
			// put more per-instance properties here
		// 声明改顶点是否位于视线域内，来判断这个顶点是否需要输出到frag中
		UNITY_INSTANCING_BUFFER_END(Props)


		void surf (Input IN, inout SurfaceOutput o) {
			// 只用最简单的颜色输出
			fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}


		//  此处的 LightingBasicDiffuse  函数的名字由两部分组成： Lighting + BasicDiffuse  
		//   BasicDiffuse  即为上面#pragma中声明的的函数
		inline float4 LightingBasicDiffuse(SurfaceOutput s,fixed3 lightDir,fixed atten)
		{
			float diffuse_term = saturate(dot(s.Normal,lightDir));
			float4 col;
			col.rgb = s.Albedo.rgb * _LightColor0.rgb * diffuse_term;
			col.a = s.Alpha;
			return col;
		}

		void final(Input IN,SurfaceOutput o,inout fixed4 color)
		{
			color = fixed4(0,1,0,1);	
		}
		

// vertex-to-fragment interpolation data
// no lightmaps:
#ifndef LIGHTMAP_ON
struct v2f_surf {
  UNITY_POSITION(pos);
  float2 pack0 : TEXCOORD0; // _MainTex
  float3 worldNormal : TEXCOORD1;
  float3 worldPos : TEXCOORD2;
  fixed3 vlight : TEXCOORD3; // ambient/SH/vertexlights
  UNITY_SHADOW_COORDS(4)
  UNITY_FOG_COORDS(5)
  #if SHADER_TARGET >= 30
  float4 lmap : TEXCOORD6;
  #endif
  UNITY_VERTEX_INPUT_INSTANCE_ID
  UNITY_VERTEX_OUTPUT_STEREO
};
#endif
// with lightmaps:
#ifdef LIGHTMAP_ON
struct v2f_surf {
  UNITY_POSITION(pos);
  float2 pack0 : TEXCOORD0; // _MainTex
  float3 worldNormal : TEXCOORD1;
  float3 worldPos : TEXCOORD2;
  float4 lmap : TEXCOORD3;
  UNITY_SHADOW_COORDS(4)
  UNITY_FOG_COORDS(5)
  #ifdef DIRLIGHTMAP_COMBINED
  float3 tSpace0 : TEXCOORD6;
  float3 tSpace1 : TEXCOORD7;
  float3 tSpace2 : TEXCOORD8;
  #endif
  UNITY_VERTEX_INPUT_INSTANCE_ID
  UNITY_VERTEX_OUTPUT_STEREO
};
#endif
float4 _MainTex_ST;

// vertex shader
v2f_surf vert_surf (appdata_full v) {
  UNITY_SETUP_INSTANCE_ID(v);
  v2f_surf o;
  UNITY_INITIALIZE_OUTPUT(v2f_surf,o);
  UNITY_TRANSFER_INSTANCE_ID(v,o);
  UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
  Input customInputData;
  vert (v, customInputData);
  o.pos = UnityObjectToClipPos(v.vertex);
  o.pack0.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
  float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
  float3 worldNormal = UnityObjectToWorldNormal(v.normal);
  #if defined(LIGHTMAP_ON) && defined(DIRLIGHTMAP_COMBINED)
  fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
  fixed tangentSign = v.tangent.w * unity_WorldTransformParams.w;
  fixed3 worldBinormal = cross(worldNormal, worldTangent) * tangentSign;
  #endif
  #if defined(LIGHTMAP_ON) && defined(DIRLIGHTMAP_COMBINED)
  o.tSpace0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
  o.tSpace1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
  o.tSpace2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
  #endif
  o.worldPos = worldPos;
  o.worldNormal = worldNormal;
  #ifdef DYNAMICLIGHTMAP_ON
  o.lmap.zw = v.texcoord2.xy * unity_DynamicLightmapST.xy + unity_DynamicLightmapST.zw;
  #endif
  #ifdef LIGHTMAP_ON
  o.lmap.xy = v.texcoord1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
  #endif

  // SH/ambient and vertex lights
  #ifndef LIGHTMAP_ON
  #if UNITY_SHOULD_SAMPLE_SH && !UNITY_SAMPLE_FULL_SH_PER_PIXEL
  float3 shlight = ShadeSH9 (float4(worldNormal,1.0));
  o.vlight = shlight;
  #else
  o.vlight = 0.0;
  #endif
  #ifdef VERTEXLIGHT_ON
  o.vlight += Shade4PointLights (
    unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0,
    unity_LightColor[0].rgb, unity_LightColor[1].rgb, unity_LightColor[2].rgb, unity_LightColor[3].rgb,
    unity_4LightAtten0, worldPos, worldNormal );
  #endif // VERTEXLIGHT_ON
  #endif // !LIGHTMAP_ON

  UNITY_TRANSFER_SHADOW(o,v.texcoord1.xy); // pass shadow coordinates to pixel shader
  UNITY_TRANSFER_FOG(o,o.pos); // pass fog coordinates to pixel shader
  return o;
}

// fragment shader
fixed4 frag_surf (v2f_surf IN) : SV_Target {
  UNITY_SETUP_INSTANCE_ID(IN);
  // prepare and unpack data
  Input surfIN;
  UNITY_INITIALIZE_OUTPUT(Input,surfIN);
  surfIN.uv_MainTex.x = 1.0;
  surfIN.uv_MainTex = IN.pack0.xy;
  float3 worldPos = IN.worldPos;
  #ifndef USING_DIRECTIONAL_LIGHT
    fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
  #else
    fixed3 lightDir = _WorldSpaceLightPos0.xyz;
  #endif
  #ifdef UNITY_COMPILER_HLSL
  SurfaceOutput o = (SurfaceOutput)0;
  #else
  SurfaceOutput o;
  #endif
  o.Albedo = 0.0;
  o.Emission = 0.0;
  o.Specular = 0.0;
  o.Alpha = 0.0;
  o.Gloss = 0.0;
  fixed3 normalWorldVertex = fixed3(0,0,1);
  o.Normal = IN.worldNormal;
  normalWorldVertex = IN.worldNormal;

  // call surface function
  surf (surfIN, o);

  // compute lighting & shadowing factor
  UNITY_LIGHT_ATTENUATION(atten, IN, worldPos)
  fixed4 c = 0;
  #ifndef LIGHTMAP_ON
  c.rgb += o.Albedo * IN.vlight;
  #endif // !LIGHTMAP_ON

  // lightmaps
  #ifdef LIGHTMAP_ON
    #if DIRLIGHTMAP_COMBINED
      // directional lightmaps
      fixed4 lmtex = UNITY_SAMPLE_TEX2D(unity_Lightmap, IN.lmap.xy);
      half3 lm = DecodeLightmap(lmtex);
    #else
      // single lightmap
      fixed4 lmtex = UNITY_SAMPLE_TEX2D(unity_Lightmap, IN.lmap.xy);
      fixed3 lm = DecodeLightmap (lmtex);
    #endif

  #endif // LIGHTMAP_ON


  // realtime lighting: call lighting function
  #ifndef LIGHTMAP_ON
  c += LightingBasicDiffuse (o, lightDir, atten);
  #else
    c.a = o.Alpha;
  #endif

  #ifdef LIGHTMAP_ON
    // combine lightmaps with realtime shadows
    #ifdef SHADOWS_SCREEN
      #if defined(UNITY_NO_RGBM)
      c.rgb += o.Albedo * min(lm, atten*2);
      #else
      c.rgb += o.Albedo * max(min(lm,(atten*2)*lmtex.rgb), lm*atten);
      #endif
    #else // SHADOWS_SCREEN
      c.rgb += o.Albedo * lm;
    #endif // SHADOWS_SCREEN
  #endif // LIGHTMAP_ON

  #ifdef DYNAMICLIGHTMAP_ON
  fixed4 dynlmtex = UNITY_SAMPLE_TEX2D(unity_DynamicLightmap, IN.lmap.zw);
  c.rgb += o.Albedo * DecodeRealtimeLightmap (dynlmtex);
  #endif

  UNITY_APPLY_FOG(IN.fogCoord, c); // apply fog
  UNITY_OPAQUE_ALPHA(c.a);
  return c;
}


#endif


ENDCG

}

	// ---- meta information extraction pass:
	Pass {
		Name "Meta"
		Tags { "LightMode" = "Meta" }
		Cull Off

CGPROGRAM
// compile directives
#pragma vertex vert_surf
#pragma fragment frag_surf
#pragma target 3.0
#pragma multi_compile_instancing
#pragma skip_variants FOG_LINEAR FOG_EXP FOG_EXP2
#pragma skip_variants INSTANCING_ON
#pragma shader_feature EDITOR_VISUALIZATION

#include "HLSLSupport.cginc"
#include "UnityShaderVariables.cginc"
#include "UnityShaderUtilities.cginc"
// -------- variant for: <when no other keywords are defined>
#if !defined(INSTANCING_ON)
// Surface shader code generated based on:
// vertex modifier: 'vert'
// writes to per-pixel normal: no
// writes to emission: no
// writes to occlusion: no
// needs world space reflection vector: no
// needs world space normal vector: no
// needs screen space position: no
// needs world space position: no
// needs view direction: no
// needs world space view direction: no
// needs world space position for lighting: no
// needs world space view direction for lighting: no
// needs world space view direction for lightmaps: no
// needs vertex color: no
// needs VFACE: no
// passes tangent-to-world matrix to pixel shader: no
// reads from normal: no
// 1 texcoords actually used
//   float2 _MainTex
#define UNITY_PASS_META
#include "UnityCG.cginc"
#include "Lighting.cginc"

#define INTERNAL_DATA
#define WorldReflectionVector(data,normal) data.worldRefl
#define WorldNormalVector(data,normal) normal

// Original surface shader snippet:
#line 8 ""
#ifdef DUMMY_PREPROCESSOR_TO_WORK_AROUND_HLSL_COMPILER_LINE_HANDLING
#endif
/* UNITY: Original start of shader */
		
		//
		// vertex: vert  第一步
		// vert  在顶点着色器中调用： 负责初始化一个 v2f_surf 的结构体

		// surf  第二步
		// 对传递进来的描述物体外表面材质属性信息的 SurfaceOutput结构体进行赋值 ，并且返回


		// BasicDiffuse  第三步
		//  在第二步的处理后，  用第二步的表面片元信息， 用BasicDiffuse 进行光照计算

		// final  第四步
		// 在最后的颜色输出之前， 对颜色进行自定义的修改，按照final 函数进行处理，并且输出返回	

		//#pragma surface surf BasicDiffuse vertex:vert finalcolor: final noforwardadd
		//#pragma target 3.0

		sampler2D _MainTex;
		float4 _Color;

		struct Input {
			float2 uv_MainTex;
		};
		void vert(inout appdata_full v,out Input o)
		{
			o.uv_MainTex = v.texcoord.xy;
		}


		//  下面两行是GPU Instance 所需要的声明 ，现在可以忽略删除
		// Add instancing support for this shader. You need to check 'Enable Instancing' on materials that use the shader.
		// See https://docs.unity3d.com/Manual/GPUInstancing.html for more information about instancing.
		// //#pragma instancing_options assumeuniformscaling
		UNITY_INSTANCING_BUFFER_START(Props)
			// put more per-instance properties here
		// 声明改顶点是否位于视线域内，来判断这个顶点是否需要输出到frag中
		UNITY_INSTANCING_BUFFER_END(Props)


		void surf (Input IN, inout SurfaceOutput o) {
			// 只用最简单的颜色输出
			fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
			o.Albedo = c.rgb;
			o.Alpha = c.a;
		}


		//  此处的 LightingBasicDiffuse  函数的名字由两部分组成： Lighting + BasicDiffuse  
		//   BasicDiffuse  即为上面#pragma中声明的的函数
		inline float4 LightingBasicDiffuse(SurfaceOutput s,fixed3 lightDir,fixed atten)
		{
			float diffuse_term = saturate(dot(s.Normal,lightDir));
			float4 col;
			col.rgb = s.Albedo.rgb * _LightColor0.rgb * diffuse_term;
			col.a = s.Alpha;
			return col;
		}

		void final(Input IN,SurfaceOutput o,inout fixed4 color)
		{
			color = fixed4(0,1,0,1);	
		}
		
#include "UnityMetaPass.cginc"

// vertex-to-fragment interpolation data
struct v2f_surf {
  UNITY_POSITION(pos);
  float2 pack0 : TEXCOORD0; // _MainTex
  UNITY_VERTEX_INPUT_INSTANCE_ID
  UNITY_VERTEX_OUTPUT_STEREO
};
float4 _MainTex_ST;

// vertex shader
v2f_surf vert_surf (appdata_full v) {
  UNITY_SETUP_INSTANCE_ID(v);
  v2f_surf o;
  UNITY_INITIALIZE_OUTPUT(v2f_surf,o);
  UNITY_TRANSFER_INSTANCE_ID(v,o);
  UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
  Input customInputData;
  vert (v, customInputData);
  o.pos = UnityMetaVertexPosition(v.vertex, v.texcoord1.xy, v.texcoord2.xy, unity_LightmapST, unity_DynamicLightmapST);
  o.pack0.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
  float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
  float3 worldNormal = UnityObjectToWorldNormal(v.normal);
  return o;
}

// fragment shader
fixed4 frag_surf (v2f_surf IN) : SV_Target {
  UNITY_SETUP_INSTANCE_ID(IN);
  // prepare and unpack data
  Input surfIN;
  UNITY_INITIALIZE_OUTPUT(Input,surfIN);
  surfIN.uv_MainTex.x = 1.0;
  surfIN.uv_MainTex = IN.pack0.xy;
  #ifdef UNITY_COMPILER_HLSL
  SurfaceOutput o = (SurfaceOutput)0;
  #else
  SurfaceOutput o;
  #endif
  o.Albedo = 0.0;
  o.Emission = 0.0;
  o.Specular = 0.0;
  o.Alpha = 0.0;
  o.Gloss = 0.0;
  fixed3 normalWorldVertex = fixed3(0,0,1);

  // call surface function
  surf (surfIN, o);
  UnityMetaInput metaIN;
  UNITY_INITIALIZE_OUTPUT(UnityMetaInput, metaIN);
  metaIN.Albedo = o.Albedo;
  metaIN.Emission = o.Emission;
  metaIN.SpecularColor = o.Specular;
  return UnityMetaFragment(metaIN);
}


#endif


ENDCG

}

	// ---- end of surface shader generated code

#LINE 74

	}
	FallBack "Diffuse"
}

悦读

道可道，非常道；名可名，非常名。 无名，天地之始，有名，万物之母。 故常无欲，以观其妙，常有欲，以观其徼。 此两者，同出而异名，同谓之玄，玄之又玄，众妙之门。

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