The minute black area on the inner part of the sector getting perceptually boosted with the same ramp width like the outer area is effectively how an outline on a shape would behave, not two shapes with no stroke width. I would expect the output brightness should scale with the volume/depth under a pixel in the 3d visualization.

Is this intentional? To me this is an opiniated (aka artistic preference) feature preserving method not the perfect one.

Btw the common visualization has a source and an author:

https://iquilezles.org/articles/distfunctions2d/ https://www.shadertoy.com/playlist/MXdSRf

Reminds me that I found an alternative way of sampling an SFD:

First take a sample in each corner of the pixel to be rendered (`s1 s2 s3 s4`), then compute:

    coverage=0.5 + (s1+s2+s3+s4)/(abs(s1)+abs(s2)+abs(s3)+abs(s4))/2

It is a good approximation, and it keeps on working no matter how you scale and stretch the field.

Relative to the standard method it is expensive to calculate. But for a modern GPU it is still a very light workload to do this once per screen pixel.

A very good example of SDF thinking, using signed distance fields in shaders. Both shaders and SDF are new to me and very interesting. Another example of what is being done is MSDF here: https://github.com/Chlumsky/msdfgen.