Shader-Normal Map In World Space

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unity Shaders Book/Chapter 7/Normal Map In World Space" {
   Properties {
       _Color ("Color Tint", Color) = (1, 1, 1, 1)
       _MainTex ("Main Tex", 2D) = "white" {}
       _BumpMap ("Normal Map", 2D) = "bump" {}
       _BumpScale ("Bump Scale", Float) = 1.0
       _Specular ("Specular", Color) = (1, 1, 1, 1)
       _Gloss ("Gloss", Range(8.0, 256)) = 20
   }
   SubShader {
       Pass {
           Tags { "LightMode"="ForwardBase" }

           CGPROGRAM

           #pragma vertex vert
           #pragma fragment frag

           #include "Lighting.cginc"

           fixed4 _Color;
           sampler2D _MainTex;
           float4 _MainTex_ST;
           sampler2D _BumpMap;
           float4 _BumpMap_ST;
           float _BumpScale;
           fixed4 _Specular;
           float _Gloss;

           struct a2v {
               float4 vertex : POSITION;
               float3 normal : NORMAL;
               float4 tangent : TANGENT;
               float4 texcoord : TEXCOORD0;
           };

           struct v2f {
               float4 pos : SV_POSITION;
               float4 uv : TEXCOORD0;
               float4 TtoW0 : TEXCOORD1;
               float4 TtoW1 : TEXCOORD2;
               float4 TtoW2 : TEXCOORD3;
           };

           v2f vert(a2v v) {
               v2f o;
               o.pos = UnityObjectToClipPos(v.vertex);

               o.uv.xy = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
               o.uv.zw = v.texcoord.xy * _BumpMap_ST.xy + _BumpMap_ST.zw;

               float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
               fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
               fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
               fixed3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;

               // Compute the matrix that transform directions from tangent space to world space
               // Put the world position in w component for optimization
               o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
               o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
               o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);

               return o;
           }

           fixed4 frag(v2f i) : SV_Target {
               // Get the position in world space
               float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);
               // Compute the light and view dir in world space
               fixed3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
               fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));

               // Get the normal in tangent space
               fixed3 bump = UnpackNormal(tex2D(_BumpMap, i.uv.zw));
               bump.xy *= _BumpScale;
               bump.z = sqrt(1.0 - saturate(dot(bump.xy, bump.xy)));
               // Transform the normal from tangent space to world space
               bump = normalize(half3(dot(i.TtoW0.xyz, bump), dot(i.TtoW1.xyz, bump), dot(i.TtoW2.xyz, bump)));

               fixed3 albedo = tex2D(_MainTex, i.uv).rgb * _Color.rgb;

               fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

               fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(bump, lightDir));

               fixed3 halfDir = normalize(lightDir + viewDir);
               fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(bump, halfDir)), _Gloss);

               return fixed4(ambient + diffuse + specular, 1.0);
           }

           ENDCG
       }
   }
   FallBack "Specular"
}

取自《Unity Shader 入门精要》

法线在世界空间下的计算

dot(i.TtoW0.xyz, bump) = i.TtoW0.x * bump.x + i.TtoW0.y * bump.y + i.TtoW0.z * bump.z，这里很巧妙的用点乘来进行矩阵运算，避免了构建一个float3x3变量和调用mul接口

Shader-Normal Map In World Space

猜你喜欢