I'm confused by the way scanlines are implemented here. They seem to have no effect on how the pixels are drawn.
What this actually seems to be is a plain old bloom filter that happens to have horizontal lines overlaid.
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.
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.