Removing falloff in the standard shader

Graphics Shaders & Materials
1

I recently stumbled across this thread when searching for a way to customise light falloff in the standard shader and was hoping somebody here could help me take it a ways further. What I want to do is have no falloff at all. Instead, I want a perfectly sharp terminator and consistent shadow darkness.

I know this sounds counterintuitive to most modern game graphics design, but I have my reasons. I’ve been messing about with UnityDeferredLibrary.cginc and have identified the two places I need to be editing for my needs.

    // spot light case
    #if defined (SPOT)   
        float3 tolight = _LightPos.xyz - wpos;
        half3 lightDir = normalize (tolight);
       
        float4 uvCookie = mul (_LightMatrix0, float4(wpos,1));
        float atten = tex2Dproj (_LightTexture0, UNITY_PROJ_COORD(uvCookie)).w;
        atten *= uvCookie.w < 0;
        float att = dot(tolight, tolight) * _LightPos.w;
        atten *= tex2D (_LightTextureB0, att.rr).UNITY_ATTEN_CHANNEL;
       
        atten *= UnityDeferredComputeShadow (wpos, fadeDist, uv);

// point light case   
    #elif defined (POINT) || defined (POINT_COOKIE)
        float3 tolight = wpos - _LightPos.xyz;
        half3 lightDir = -normalize (tolight);
       
        float att = dot(tolight, tolight) * _LightPos.w;
        float atten = tex2D (_LightTextureB0, att.rr).UNITY_ATTEN_CHANNEL;
       
        atten *= UnityDeferredComputeShadow (tolight, fadeDist, uv);
       
        #if defined (POINT_COOKIE)
        atten *= texCUBE(_LightTexture0, mul(_LightMatrix0, half4(wpos,1)).xyz).w;
        #endif //POINT_COOKIE   
    #else
        half3 lightDir = 0;
        float atten = 0;
    #endif

Unfortunately, that’s where I end up stumped. I’m not sure how I’m supposed to change the atten value or where to achieve the results I want. Can anyone help me with this, please?

2

By changing att to equal 0, I managed to accomplish what I want, but now I’m left with some awkward side effects. While the spot light looks mostly fine, the point light has some strange behaviour that makes it kind of jerk around awkwardly around its edges. See video:

Is there any way I can mask this problem?