右侧BumpScale为1

Shader "UnityShaderLearning/NormalMapTangentSpace"
{
  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;
              float3 LightDir : TEXCOORD1;
              float3 ViewDir : TEXCOORD2;
          };

          v2f vert(a2v v)
          {
              v2f o;
              o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
              o.uv.xy = v.vertex.xy * _MainTex_ST.xy + _MainTex_ST.zw;
              o.uv.zw = v.vertex.xy * _BumpMap_ST.xy + _BumpMap_ST.zw;
              float3 binormal = cross(normalize(v.normal), normalize(v.tangent.xyz));
              float3x3 rotation = float3x3(v.tangent.xyz, binormal, v.normal);
              o.LightDir = mul(rotation, ObjSpaceLightDir(v.vertex)).xyz;
              o.ViewDir = mul(rotation, ObjSpaceViewDir(v.vertex)).xyz;

              return o;
          }

          fixed4 frag(v2f i) : SV_Target
          {
              fixed3 tangentLightDir = normalize(i.LightDir);
              fixed3 tangentViewDir = normalize(i.ViewDir);
              fixed4 packedNormal = tex2D(_BumpMap, i.uv.zw);
              fixed3 tangentNormal;
              // tangentNormal.xy = (packedNormal.xy * 2 - 1) * _BumpScale;
              // tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));

              tangentNormal = UnpackNormal(packedNormal);
              tangentNormal.xy *= _BumpScale;
              tangentNormal.z = sqrt(1.0 - saturate(dot(tangentNormal.xy, tangentNormal.xy)));

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

              fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(tangentNormal, tangentLightDir));
              fixed3 halfDir = normalize(tangentViewDir + tangentLightDir);
              fixed3 specular = _LightColor0 * _Specular.rgb * pow(max(0, dot(tangentNormal, halfDir)), _Gloss);

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

          ENDCG
      }
  }
  FallBack "specular"
}