A flowing WebGL gradient, deconstructed
14 comments
·April 12, 2025mwkaufma
danwills
Quite right! I think if the values were linearized (~gamma 0.5) lerp might be mostly ok though, right?
And what about doing rgb->hsv, then lerp, then hsv->rgb? I'm unclear whether that also needs linearization, or whether the gamma can maybe just be done to the 'v' component before lerping?
Color is a surprisingly deep and fascinating topic, that's for sure! :)
mwkaufma
Perceptual colors -- both sRGB and HSB -- are nonlinear, so you can't expect linear combinations to produce meaningful results (they often "interpolate through mud").
If you just want optical phenomena, you can just convert to luminescence -- WegGL and other modern graphics APIs actually does this internally when you load or render textures, so all shaders are handling optically-linear data, which is why the shader-produced images in the post look better than the javascript gradients.
pornel
Mixing of colors in an "objective" way like blur (lens focus) is a physical phenomenon, and should be done in linear color space.
Subjective things, like color similarity and perception of brightness should be evaluated in perceptual color spaces. This includes sRGB (it's not very good at it, but it's trying).
Gradients are weirdly in the middle. Smoothness and matching of colors are very subjective, but color interpolation is mathematically dubious in most perceptual color spaces, because √(avg(a+b)) ≠ avg(√(a) + √(b))
itishappy
To be fair, lerp still mixes colors, it just mixes ugly colors.
sly010
Very cool, but by css-rotating (skewY(-6deg)) the canvas at the last moment, you introduced aliasing on the border between the canvas and the rest of the page which kills the vibe. The browser can't automatically blend the canvas with the rest of the page. It's noticeable even on a brand new retina display. Maybe you could keep your canvas square and introduce the skew in the shader.
danwills
Guess it depends on the browser as it looks sharp and free of aliasing for me, including when zooming in (Opera on Android)
herpdyderp
- Safari: decent but still obviously present
- Chrome: quite bad looking
- Firefox: something in between
andrewmcwatters
The funny thing is, as far as I know, skewY is a virtual draw command in the WebKit family of rendering engines.
It's "in the shader" already. For whatever reason, your browser's compositor is failing to anti-alias the rendering bounds of the canvas.
I don't know why, though. I don't see the issue in Safari on my system.
mrmagoo17
We need more articles as polished as this one. WebGL is a topic I wanted to get into for a while now but it's really difficult to find good content about it. Please keep sharing more experiments!
herpdyderp
The linked source code [0] doesn't seem to have any license attached to it. So how could I actually use this? Is it published as a package somewhere, like npm?
0. https://github.com/alexharri/website/blob/eb9551dd7312685704...
heinternets
This looks very smooth. Would this be in 10 bit colour if the display supports it? I can't see any banding even when zoomed in Safari or Brave on a MBP with HDR display.
ikesau
Jesus christ, this is such a polished article. Writing it must have taken at least 5 times as long as the shader!
Have reblogged it and will refer back to it if ever I have some time to learn how to write them :)
polygot
Reminds me of the JetBrains installer--not a bad reminder, I like the animations.
>> The mix function is an interpolation function that linearly interpolates between the two input colors using a blend factor between and ( in our case).
>> A mix function for two colors works the same way, except we mix the color components. To mix two RGB colors, for example, we’d mix the red, green, and blue channels.
Colorspace alert! mix != lerp in sRGB