Implementation of simple matcap+fresnel shader in unity

Shader "Unlit/matcap"{
    //matcap
    Properties{
        _NormalMap(" Normal map ", 2D) = "bump" {}
        _Matcap("matcap", 2D) = "white" {}
        _FresnelPow(" Fresnel intensity ",Range(0,5)) = 1
        _EnvSpeInt(" Environmental reflection intensity ",Range(0,5)) = 1
    }
        SubShader{
            Tags {
                "RenderType" = "Opaque"
            }
            Pass {
                Name "FORWARD"
                Tags {
                    "LightMode" = "ForwardBase"
                }

                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #include "UnityCG.cginc"
                #pragma multi_compile_fwdbase_fullshadows
                #pragma target 3.0
            // Input parameters 
            uniform sampler2D _NormalMap;
            uniform sampler2D _Matcap;
            uniform float _FresnelPow;
            uniform float _EnvSpeInt;
            // Input structure 
            struct VertexInput {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
                float2 uv0 : TEXCOORD0;
            };
            // Output structure 
            struct VertexOutput {
                float4 pos : SV_POSITION;
                float2 uv0 : TEXCOORD0;
                float3 nDirWS : TEXCOORD1;
                float3 tDirWS : TEXCOORD2;
                float3 bDirWS : TEXCOORD3;
                float3 posWS : TEXCOORD4;
            };
            VertexOutput vert(VertexInput v) {
                VertexOutput o = (VertexOutput)0;
                o.uv0 = v.uv0;
                o.nDirWS = UnityObjectToWorldNormal(v.normal);
                o.tDirWS = normalize(mul(unity_ObjectToWorld, float4(v.tangent.xyz, 0.0)).xyz);
                o.bDirWS = normalize(cross(o.nDirWS, o.tDirWS) * v.tangent.w);
                o.pos = UnityObjectToClipPos(v.vertex);
                o.posWS = mul(unity_ObjectToWorld,v.vertex);
                return o;
            }
            // Pixels shader
            float4 frag(VertexOutput i) : COLOR{
                // Vector preparation 
                float3  nDirTS = UnpackNormal(tex2D(_NormalMap, i.uv0)).rgb;
                float3x3 tbn = float3x3(i.tDirWS, i.bDirWS, i.nDirWS);
                float3 nDirWS = normalize(mul(nDirTS, tbn));
                float3 nDirVS = mul(UNITY_MATRIX_V,float4(nDirWS,0.0));
                float3 vDirWS = normalize(_WorldSpaceCameraPos.xyz - i.posWS.xyz);

                // Intermediate quantity preparation 
                float2 mapUV = nDirVS.rg * 0.5 + 0.5;
                float ndotv = dot(nDirWS,vDirWS);

                // Illumination model 
                float3 matcap = tex2D(_Matcap, mapUV);
                float fresnel = pow(1.0-ndotv, _FresnelPow);
                float3 envSpcLighting = matcap * fresnel * _EnvSpeInt;

                // Return value 
                                return fixed4(envSpcLighting,1);
                            }
                            ENDCG
                        }
    }
        FallBack "Diffuse"
}

Realization effect ：