Split apply_pbr_lighting into many many small functions

[ethereumdegen]

What problem does this solve or what need does it fill?

Please split apply_pbr_lighting into many many small functions. You can keep the function name the same and what it does the same. But please make it perform a bunch of small functions which can be called individually for when we are making Extension Material Shaders.

This is because I want to change the way shadows work (cel shading) but it seems VERY VERY horribly hard to do with the way that apply_pbr_lighting is so monolithic right now.

What solution would you like?

for example I want each input of this line to have its own small function

   // Total light
    output_color = vec4<f32>(
        (view_bindings::view.exposure * (transmitted_light + direct_light + indirect_light)) + emissive_light,
        output_color.a
    );

And i want to be able to effectively easily modify that specific line of code in my extension material shader . Right now, I have to completely re-write (re-implement) the entirety of apply_pbr_lighting just to change the way direct light affects my output color because this is too monolithic.

What alternative(s) have you considered?

Offer a few preset different apply_pbr_lighting functions that work differently? Make some of them have different input props or a bit flag to be able to change the way inner parts of it work?

But overall i think the best soln here is to just take chunks of the innards of apply_pbr_lighting and put them into small functions which apply_pbr_lighting calls. That way, I can implement those small functions into my shader exactly how i wish and only have to rewrite perhaps a small part of apply_pbr_lighting to change the way my color reacts to point and dynamic lights. !

Additional context

[pcwalton]

I agree with this generally. I would go so far as to say that it should be possible for a machine to autogenerate apply_pbr_lighting from its constituent parts. That way, artists could create the same effect with a shader graph.

[ethereumdegen]

Okay i have an even better idea. Check this out.

Make a function 'calculate_pbr_lighting' that has ALL of the code of apply_pbr_lighting except it returns

return  ( transmitted_light, direct_light, indirect_light, emissive_light )  

And then make apply_pbr_lighting just call that and do this

  output_color = vec4<f32>(
        (view_bindings::view.exposure * (transmitted_light + direct_light + indirect_light)) + emissive_light,
        output_color.a
    );

That way, we are hardly changing the code at all but also making it WAY more extensible

[ethereumdegen]

please reopen - i didnt mean to close !

[ethereumdegen]

fn compute_pbr_lighting(
    in: pbr_types::PbrInput,
) -> ComputedPbrLighting {
     

.... alll the lighting code ... 

    return ComputedPbrLighting (
        transmitted_light,
        direct_light,
        indirect_light,
        emissive_light,
   )
}


fn apply_pbr_lighting(
    in: pbr_types::PbrInput,
) -> vec4<f32> {
     

    let computed_pbr_lighting = compute_pbr_lighting( in ) ;


    // Total light
    output_color = vec4<f32>(
        (view_bindings::view.exposure * (computed_pbr_lighting.transmitted_light + computed_pbr_lighting.direct_light + computed_pbr_lighting.indirect_light)) + computed_pbr_lighting.emissive_light,
        output_color.a
    );

    output_color = clustering::cluster_debug_visualization(
        output_color,
        view_z,
        in.is_orthographic,
        offset_and_counts,
        cluster_index,
    );

    return output_color;
}
 

[ethereumdegen]

See? now it is split into a read-only computation fn and a mutation function. This is way better for extension shader. Only have the mutation function was not.