Vertex shader with extrusion, what am I doing wrong?

Unity Engine
1

So for a simple surface shader, you can use vertex modifier:

      void vert (inout appdata_full v) {
          v.vertex.xyz += v.normal * _Amount;
      }

I was thinking the same would work as vertex shader:

            // vertex shader
            VectexOutput vert (VectexInput i) {
                // init output
                VectexOutput o;
                UNITY_INITIALIZE_OUTPUT(VectexOutput, o);

                // vertex extrusion
                i.vertex.xyz += i.normal * _Multiplier;

                // world space normal
                half3 normal = UnityObjectToWorldNormal(i.normal);

                // standard diffuse lighting
                half nl = max(0, dot(normal, _WorldSpaceLightPos0.xyz));

                // input to output
                o.vertex = UnityObjectToClipPos(i.vertex);
                o.color = i.color;
                o.diff = nl * _LightColor0;
                o.diff.rgb += ShadeSH9(half4(normal, 1));
                o.uv = TRANSFORM_TEX(i.uv, _MainTex);

                return o;
            }

But it doesn’t, and since surface shader is compiled to vertex/fragment shader, I am wondering what am I missing?

2

I think you want to extrude it by the world normal?