Yeah it's not a CRT simulator. It's a minimal shader to give a CRT-like vibe. Minimal as in the least amount of processing, so it performs well on older devices.

A better demo would correlate the pixelization of the source with the settings in the sidebar. Doesn't even have to be part of the shader, but would convey the effect better. The animated shapes toggle really kills the illusion.

A Bloom filter?

Never mind, I'm guessing you mean a different kind.

Nice to see you on HN and thanks for webglfundamentals!

How are they different/better/worse?

People have varying sensitivies to flicker, but the refresh rate of even basic cheap CRT monitors was something like 75 or 85 Hz, which most people found essentially flickerless. Higher-end monitors would go up to 100 or 120 Hz, one of the several ways that for some use cases they were superior to LCD displays for quite a long time. Televisions, at 50 or 60 Hz, were pretty bad of course.

This CRT shader actually has a flicker slider. But 'brain melting flicker' sounds more like you were gaming with a 50Hz PAL console (or home computer) on a professional computer monitor which was intended for higher frequencies (like 72Hz). Regular TVs normally had plenty of 'afterglow' to reduce flicker.

Have you tried BFI (black frame insertion)? Many people swear by it because it improves the "motion clarity", but it has the side effect of significantly increasing flicker.

Of course that is also available as a shader: https://news.ycombinator.com/item?id=42506211

This shader manages to do it, it gives a very realistically familiar unpleasant feeling of an old low refresh TV.

(on a 144Hz monitor... it's supposedly less unpleasant with a 250Hz one)

They also don't replicate the 15khz whine that makes CRTs incredibly annoying for me to use

All of them make my eyes water, som they are doing something right.

Yet still the 'raw' pixel data of old games rendered on modern displays without any filtering also doesn't look anything like they looked on CRT monitors (and even on CRT monitors there's a huge range between "game console connected to a dirt cheap tv via coax cable" and "desktop publishing workstation connected to professional monitor via VGA cable").

All the CRT shaders are just compromises on the 'correctness' vs 'aesthetics' vs 'performance' triangle (and everybody has a different sweet spot in this triangle, that's why there are so many CRT shaders to choose from).

Most of these CRT shaders seem to emulate the lowest possible quality CRTs you could find back in the day. I have a nice Trinitron monitor on my desk and it looks nothing like these shaders.

The only pleasant shader I have found is the one included in Dosbox Staging (https://www.dosbox-staging.org/), that one actually looks quite similar to my monitor!

In theory, good CRT shader emulates temporal and "subpixel" tricks that game developers used to overcome color and resolution limitations.

Mostly, it's retro aesthetic for people who actually did not grow with CRT displays.

Torture.

OP here. Red does bleed that way with this, you can see the lines almost disappear (especially with vertical movement) if you enable the coloured shape layer which was added specifically for this purpose.

But it's not displaying any specific CRT, TV, PVM, etc. It's not a simulator, rather just a minimal (as in GPU work it results in) shader to give that kind of vibe/aesthetic.