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GLSL Web CRT Shader
- msephton 10mo agoRevised title: WebGL CRT Shader
- sublinear 10mo agoI'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.
- bsimpson 10mo agoA 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.
- msephton 10mo agoThe animated shapes are off by default. They're there only so you can see how the settings affect red, green, and blue individually and in motion. For example with some settings the scanlines tend to disappear on red when in motion.
- msephton 10mo agoYeah 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.
- JKCalhoun 10mo agoA Bloom filter? Never mind, I'm guessing you mean a different kind.
- flohofwoe 10mo agoIn rendering, bloom filter means this thing: https://en.wikipedia.org/wiki/Bloom_(shader_effect) https://en.wikipedia.org/wiki/Bloom_(shader_effect) ...the other Bloom filter is named after a person.
- greggman65 10mo agoThere's several of these on shadertoy https://www.shadertoy.com/results?query=crt https://www.shadertoy.com/results?query=crt I made a Pico-8 post processing script using a few https://greggman.github.io/pico-8-post-processing/nano-villager_html/ https://greggman.github.io/pico-8-post-processing/nano-villa... also an article on starting one on WebGPU here https://webgpufundamentals.org/webgpu/lessons/webgpu-post-processing.html https://webgpufundamentals.org/webgpu/lessons/webgpu-post-pr...
- msephton 10mo agoHow are they different/better/worse?
- zokier 10mo agoCRT shaders are a rabbit hole. Retro gaming/emulator community has been iterating on them for a while now. Found this blog post with tons of comparisons between different shaders in different configurations: https://thingsiplay.game.blog/2024/10/19/showcase-for-retroarch-shaders-2024/ https://thingsiplay.game.blog/2024/10/19/showcase-for-retroa...
- skywal_l 10mo agoNice to see you on HN and thanks for webglfundamentals!
- archerx 10mo agoWhat's the point of these? I grew up using CRT monitors and TVs and they look nothing like the shaders.
- flohofwoe 10mo agoYet 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).
- Sharlin 10mo agoMostly, it's retro aesthetic for people who actually did not grow with CRT displays.
- OuterVale 10mo agoYou say this, but the author was born in 1976. It not being perfect doesn't mean that the person involved doesn't know what they're talking about.
- msephton 10mo agoIndeed. I made this because I grew up with CRTs and miss that vibe. As I say on the page: it's not scientifically accurate, but it looks good, and gives the same sort of feeling. And more than that uses minimal shader code so it works well on older devices. I'm currently making a 3D game that uses this shader and it runs at 60fps an iPhone XS (2018).
- pezezin 10mo agoMost 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/ https://www.dosbox-staging.org/), that one actually looks quite similar to my monitor!
- okasaki 10mo agoOne thing I haven't seen CRT shaders really replicate is the brain-melting flicker that comes with that technology. LCD was such a relief when it became common.
- flohofwoe 10mo agoThis 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.
- Sharlin 10mo agoPeople 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.
- pezezin 10mo agoHave 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.
- voidUpdate 10mo agoThey also don't replicate the 15khz whine that makes CRTs incredibly annoying for me to use
- onion2k 10mo agoI've always thought it's a shame that CSS PaintWorklets (https://developer.chrome.com/blog/paintapi/ https://developer.chrome.com/blog/paintapi/) can't access DOM elements to apply GLSL effects to things on a page. I understand why (it'd be a security nightmare having things rendered by something that's not the browser) but it's still annoying. I could make some cool stuff.
- spankalee 10mo agohttps://github.com/WICG/html-in-canvas https://github.com/WICG/html-in-canvas
- swiftcoder 10mo agoOh, these are fun. I whipped one up for ludumdare 57 - https://swiftcoder.github.io/fathom/ https://swiftcoder.github.io/fathom/ Shader source: https://github.com/swiftcoder/fathom/blob/cd56fce9528641c7ed177da70876bf478d90b4fa/src/post_processor.rs#L221-L264 https://github.com/swiftcoder/fathom/blob/cd56fce9528641c7ed...
- dylan604 10mo agoWhat CRT standard is this meant to be emulating? It can't be NTSC, it's too clean. Red would never display that cleanly. Red was infamous for bleeding as the saturation increased. Never had much experience with True PAL in that I've only ever seen PAL at 60Hz so I'm not sure if had the same bleeding red issue. It's these kinds of details that can really set your yet another emulator apart
- msephton 10mo agoOP 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.