vertex distortion in shaderlab

Question

I'm rather new to shaderlab with unity. I am trying to distort the vertices so that they are push backwards and towards the camera almost like looking at the camera from a 45 degree angle. I am replicating an effect from a game for fun. This is the code used for the effect

ive tried implenting the code into a shader script like so:

float4 vert(appdata v){

            float3 position = mul(unity_ObjectToWorld, v.vertex).xyz;

            float y = position.y;
            float z = position.x;

            float3 parentTranslation = ParentMatrix._m30_m31_m32;

            position -= parentTranslation;
            position.z += AlternateLayeringScale;
            position.z -= y;
            position.y += position.z;
            position += parentTranslation + float3(0,parentTranslation.z,0);

            return position;

        }

however i get an error stating it cannot convert from float3 to float4, i am not sure how it was implemented

Answer 1

The fourth part is 'w' also called the inverse stretching factor. To convert from vec4 to vec3 it's best to do position.xyz / position.w and to put it back in a vec4 you can write return fixed4(position, 1)