Unity中Shader的Standard材质解析（一）

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前言

在Unity中，实现PBR材质的Shader

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一、在Unity中，按一下步骤准备

1、在资源管理面板创建一个 Standard Surface Shader

2、因为Standard Surface Shader有很多缺点，所以我们把他转化为顶点片元着色器

• 点击Show generated code

• 把生成后的，顶点片元着色器代码复制过去

• 这样我们就可以得到一个简单的PBR材质了

3、整理只保留主平行光的Shader效果

4、精简后的最终代码

最终效果：

• 给予对应纹理

//Standard材质
Shader "MyShader/P2_2_4"
{Properties{_Color ("Color", Color) = (1,1,1,1)_MainTex ("Albedo (RGB)", 2D) = "white" {}[NoScaleOffset]_MetallicTex("Metallic(R) Smoothness(G) AO(B)",2D) = "white" {}[Normal]_NormalTex("NormalTex",2D) = "bump" {}_Glossiness ("Smoothness", Range(0,1)) = 0.0_Metallic ("Metallic", Range(0,1)) = 0.0_AO("AO",Range(0,1)) = 1.0}SubShader{Tags{"RenderType"="Opaque"}LOD 200// ---- forward rendering base pass:Pass{Name "FORWARD"Tags{"LightMode" = "ForwardBase"}CGPROGRAM// compile directives#pragma vertex vert#pragma fragment frag#pragma target 3.0#pragma multi_compile_instancing#pragma multi_compile_fog#pragma multi_compile_fwdbase#include "UnityCG.cginc"#include "Lighting.cginc"#include "UnityPBSLighting.cginc"#include "AutoLight.cginc"sampler2D _MainTex;float4 _MainTex_ST;half _Glossiness;half _Metallic;fixed4 _Color;sampler2D _MetallicTex;half _AO;sampler2D _NormalTex;struct appdata{float4 vertex : POSITION;float4 tangent : TANGENT;float3 normal : NORMAL;float4 texcoord : TEXCOORD0;float4 texcoord1 : TEXCOORD1;float4 texcoord2 : TEXCOORD2;float4 texcoord3 : TEXCOORD3;fixed4 color : COLOR;UNITY_VERTEX_INPUT_INSTANCE_ID};// vertex-to-fragment interpolation data// no lightmaps:struct v2f{float4 pos : SV_POSITION;float2 uv : TEXCOORD0; // _MainTexfloat3 worldNormal : TEXCOORD1;float3 worldPos : TEXCOORD2;#if UNITY_SHOULD_SAMPLE_SHhalf3 sh : TEXCOORD3; // SH#endif//切线空间需要使用的矩阵float3 tSpace0 : TEXCOORD4;float3 tSpace1 : TEXCOORD5;float3 tSpace2 : TEXCOORD6;UNITY_FOG_COORDS(7)UNITY_SHADOW_COORDS(8)};// vertex shaderv2f vert(appdata v){v2f o;o.pos = UnityObjectToClipPos(v.vertex);o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;float3 worldNormal = UnityObjectToWorldNormal(v.normal);//世界空间下的切线half3 worldTangent = UnityObjectToWorldDir(v.tangent);//切线方向half tangentSign = v.tangent.w * unity_WorldTransformParams.w;//世界空间下的副切线half3 worldBinormal = cross(worldNormal, worldTangent) * tangentSign;//切线矩阵o.tSpace0 = float3(worldTangent.x, worldBinormal.x, worldNormal.x);o.tSpace1 = float3(worldTangent.y, worldBinormal.y, worldNormal.y);o.tSpace2 = float3(worldTangent.z, worldBinormal.z, worldNormal.z);o.worldPos.xyz = worldPos;o.worldNormal = worldNormal;// SH/ambient and vertex lights#if UNITY_SHOULD_SAMPLE_SH && !UNITY_SAMPLE_FULL_SH_PER_PIXELo.sh = 0;// Approximated illumination from non-important point lights#ifdef VERTEXLIGHT_ONo.sh += 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);#endifo.sh = ShadeSHPerVertex (worldNormal, o.sh);#endifUNITY_TRANSFER_LIGHTING(o, v.texcoord1.xy);UNITY_TRANSFER_FOG(o, o.pos); // pass fog coordinates to pixel shaderreturn o;}// fragment shaderfixed4 frag(v2f i) : SV_Target{UNITY_EXTRACT_FOG(i);float3 worldPos = i.worldPos.xyz;float3 worldViewDir = normalize(UnityWorldSpaceViewDir(worldPos));SurfaceOutputStandard o;UNITY_INITIALIZE_OUTPUT(SurfaceOutputStandard, o);fixed4 mainTex = tex2D(_MainTex, i.uv);o.Albedo = mainTex.rgb * _Color;o.Emission = 0.0;fixed4 metallicTex = tex2D(_MetallicTex, i.uv);o.Metallic = metallicTex.r * _Metallic;o.Smoothness = metallicTex.g * _Glossiness;o.Occlusion = metallicTex.b * _AO;o.Alpha = 1;half3 normalTex = UnpackNormal(tex2D(_NormalTex,i.uv));half3 worldNormal = half3(dot(i.tSpace0,normalTex),dot(i.tSpace1,normalTex),dot(i.tSpace2,normalTex));o.Normal = worldNormal;// compute lighting & shadowing factorUNITY_LIGHT_ATTENUATION(atten, i, worldPos)// Setup lighting environmentUnityGI gi;UNITY_INITIALIZE_OUTPUT(UnityGI, gi);gi.indirect.diffuse = 0;gi.indirect.specular = 0;gi.light.color = _LightColor0.rgb;gi.light.dir = _WorldSpaceLightPos0.xyz;// Call GI (lightmaps/SH/reflections) lighting functionUnityGIInput giInput;UNITY_INITIALIZE_OUTPUT(UnityGIInput, giInput);giInput.light = gi.light;giInput.worldPos = worldPos;giInput.worldViewDir = worldViewDir;giInput.atten = atten;#if defined(LIGHTMAP_ON) || defined(DYNAMICLIGHTMAP_ON)giInput.lightmapUV = IN.lmap;#elsegiInput.lightmapUV = 0.0;#endif#if UNITY_SHOULD_SAMPLE_SH && !UNITY_SAMPLE_FULL_SH_PER_PIXELgiInput.ambient = i.sh;#elsegiInput.ambient.rgb = 0.0;#endifgiInput.probeHDR[0] = unity_SpecCube0_HDR;giInput.probeHDR[1] = unity_SpecCube1_HDR;#if defined(UNITY_SPECCUBE_BLENDING) || defined(UNITY_SPECCUBE_BOX_PROJECTION)giInput.boxMin[0] = unity_SpecCube0_BoxMin; // .w holds lerp value for blending#endif#ifdef UNITY_SPECCUBE_BOX_PROJECTIONgiInput.boxMax[0] = unity_SpecCube0_BoxMax;giInput.probePosition[0] = unity_SpecCube0_ProbePosition;giInput.boxMax[1] = unity_SpecCube1_BoxMax;giInput.boxMin[1] = unity_SpecCube1_BoxMin;giInput.probePosition[1] = unity_SpecCube1_ProbePosition;#endifLightingStandard_GI(o, giInput, gi);// PBS的核心计算fixed4 c = LightingStandard(o, worldViewDir, gi);UNITY_APPLY_FOG(_unity_fogCoord, c); // apply fogUNITY_OPAQUE_ALPHA(c.a); //把c的Alpha置1return c;}ENDCG}}}