How do you fake a shader? What does that mean?

You simulate them running in the browser instead of a GPU

You mean the CPU right? Browsers can send commands to the GPU too.

It's an HTML canvas, but you can give it input similar to a shading language?

Suggestion

change the line

    `${lib};const {sin,cos,tan,random,PI,sqrt,hypot,atan,atan2} = Math; ${code}; return main;`

to

    `${lib};const {${Object.getOwnPropertyNames(Math)}} = Math; ${code}; return main;

To bring in all of Math into context without having to list them all individually.

Maybe also adding smoothstep and clamp as traditional shader building blocks functions.

You can still define them in inline with not too many characters though so maybe it's ok.

https://garten.salat.dev/fake-shaders3.html#Zy5kaW09NjQ7bGV0...

wow that's cool