Up-Down, Left-Right facing ratio shader

Question

A little basic question i can't get my head around. I need to create a shader that works like a facing ratio shader however also containing up-down and left-right (in screen space).

Just like this:

I want it to work without having the original geometry, only having the normals, point position and the camera position. How should i approach this?

Answer 1

Here's your shader:

#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"

struct app2vert
{
    float4 position: POSITION;
    float3 normal: NORMAL;
};

struct vert2frag
{
    float4 position: POSITION;
    float3 normal: TEXCOORD0;
};

vert2frag vert(app2vert input)
{
    vert2frag output;
    output.position = mul(UNITY_MATRIX_MVP, input.position);
    output.normal = mul((float3x3)UNITY_MATRIX_IT_MV, input.normal);
    return output;
}

float4 frag(vert2frag input) : COLOR
{
    float3 normal = normalize(input.normal);
    float4 output = fixed4(normal.x, normal.y, normal.z, 1.0f);

    return output;
}