For folks who wanted a less intensive glass effect, they could pick and choose from the tutorial. You get a pretty respectable piece of glass at step three with just blur and shadow. I'd personally recommend doing that and mixing in a static light ray image. IDT most applications would need the full JavaScript effect. It's fun but it can be distracting.
With blur, shadow, and light rays alone you can already get _really close_ to that Forza image at the top.
I really like the aestectics, even if physically wrong at the edges. Thanks for sharing the details.
As a embedded developer, I feel this is kind of wasteful. Every client computes an "expensive" blur filter, over an over again? Just for blending to a blurred version of the background image?
I know - this is using the GPU, this is optimized. In the end, this should not be much. (is it really?)
<rant> I feel the general trend with current web development is too much bloat. Simple sites take 5 seconds to load? Heavy lifting on the client? </rant>... but not the authors fault
I guess everybody has their own preconceptions of what's wasteful.
I grew up in the era of 14.4k modems, so I'm used to thinking that network bandwidth is many, many orders of magnitude more scarce and valuable than CPU time.
To me, it's wasteful to download an entire image over the Internet if you can easily compute it on the client.
Think about all the systems you're activating along the way to download that image: routers, servers, even a disk somewhere far away (if it's not cached on the server)... All that just to avoid one pass of processing on data you already had in RAM on the client.
I have the same perspective regarding bandwidth, but I also consider any client to be running on a computer at least ten years old and at least three OS revisions behind.
I like to consider myself a guest on a client CPU, GPU, and RAM. I should not eat all their food, leave an unflushed turd in their toilet, and hog the remote control. Be a thoughtful guest that encourages feelings of inviting me back in the future.
Load fast, even when cell coverage is marginal. Low memory so a system doesn't grind to a halt from swapping. Animate judiciously because it's polite. Good algorithms, because everyone notices when their cursor becomes jerky.
"Mips – processing cycles, computer power – had always been cheaper than bandwidth. The computers got cheaper by the week and the phone bills stayed high by the month." - The Star Fraction, 1995
If the goal is to optimize for server bandwidth, wouldn't you still want to send the already-blurred photo? Surely that will be a smaller image size than the pre-blurred full res photo (while also reducing client-side CPU/OS requirements).
Okay but how do you compute an image? How would your browser -- or any other client software -- know what's the hero image of a blog that you never visited before, for example?
I feel like I am missing something important in your comment.
The article describes computational method of rendering frosted glass effect. You can achieve the same thing by rendering the effect once (then upload to a sever) and have client download the rendered image. Or you can compute the frosted glass effect. What's better? That's the argument.
Ah, sorry, I didn't make it as far in the article.
IMO it really depends on the numbers. I'd be OK if my client downloads 50KB extra data for the already-rendered image but I'll also agree that from 100KB and above it is kind of wasteful and should be computed.
With the modern computing devices we all have -- including 3rd world countries, where a cheap Android phone can still do a lot -- I'd say we should default to computation.
Most of those websites that are technically "wasteful" in some ways, are way more "wasteful" when you realize what we use them for. Mostly it's for pure entertainment.
So either entertainment is wasteful, or if it's not, spending more compute to make the entertainment better is OK.
I would say most websites are wasteful wrt the customer, which is usually advertisers. There are websites where the user is the customer, but they’re rare these days.
Isn't sending both the blurred and non-blurred picture over the network the way we did it since two decades in web dev? With (many!) high resolution pictures this is definetly less performant then a local computation, given that real networks have finite bandwiths, in particular mobile clients on spots with bad wireless coverage. It is astonishing what can be done with CSS/WebGL only these days. We needed a lot of hacks and workarounds in the past for that.
I don't have much data myself but when I was doing scraping some time ago I had thousands of examples where f.ex. the full-res image was something like 1.7MB and the blurred image was in the range of 70KB - 200KB, so more or less 7% - 11% of the original. And I might be lying here (it's been a while) but I believe at least 80% of the blurred images were 80KB or less.
Technically yes you could make some savings but since images were transferred over an HTTP-1.1 Keep-Alive connection, I don't feel it was such a waste.
Would love to get more data if you have it, it's just that from the limited work I did in the area it did not feel very worth of only downloading the high-res image and do the blur yourself... especially in scenarios when you just need the blurred image + dimensions first, in order to prevent the constant annoying visual reflow as images are downloaded -- something _many_ websites suffer from even today.
As per the central limit theorem one can approximate Gaussian with a repeated convolution with any function, box blur being most obvious candidate here. And box blur can be computed quickly with a summed area table.
I really wonder what's the field of reference of "quickly" there. To me convolution is one of the last resort techniques in signal processing given how expensive it is (O(size of input data * size of convolution kernel)). It's of course still much faster than gaussian blur which is still non-trivial to manage at a barely decent 120fps even on huge Nvidia GPUs but still.
I would argue that while it _feels_ wasteful to us humans, as we perceive it as a "big recomputation of the rendered graphics", technically it's not.
the redrawing of anything that changes in your ui requires gpu computation anyway, and some simple blur is quite efficient to add. Likely less expensive than any kind of animations of dom objects thar aren't optimized as gpu layers.
additionally, seeing how nowadays the most simple sites tend to load 1+ mb of JS and trackers galore, all eating at your cpu ressources, Id put that bit of blur for aesthetics very far down on the "wasteful" list
I guess eventually it's a trade-off between doing heavy lifting yourself and paying a little more compute and bandwidth, or offloading it to clients and wasting more energy but at lower cost to the developer. I think there are environmental arguments in both directions (more energy spent computing stuff on the client vs more energy sending pre-computed assets over the networks). I'm not sure which is better ultimately - I suppose it varies case-by-case.
First, I really like the effect the author has achieved. It's very pretty.
Now for a bit of whimsy. It's been said that a picture is worth a thousand words. However, a thousand words uses far less bandwidth. What if we go full-tilt down the energy saving path, replace some images with prose to describe them? What would articles and blog posts look like then?
I know it's not practical, and sending actual images saves a lot of time and effort over trying to describe them, but I like the idea of imagining what that kind of web might look like.
With a standardized diffusion model on the receiving end, and a starting point image (maybe 16x16 pixels) with a fixed seed, we could send images with tiny amounts of data, with the client deciding the resolution (deciding how much compute to dedicate) as well as whatever local flavor they wanted (display all images in the style of Monet…) bandwidth could be minimized and the user experience deeply customized.
We’d just be sending prompts lol. Styling , css, etc all could receive similar treatment, using a standardized code generating model and the prompt/seed that generates the desired code.
Just need to figure out how to feed code into a model and have it spit out the prompt and seed that would generate that code in its forward generation counterpart.
Tbh I think people radically underestimate how fast, and efficiently so, GPUs are. The Apple Watch has physically based rendering in the UI. It would be curious to compare the actual cost of that versus using a microcontroller to update a framebuffer pushed to a display via SPI.
I did some webgl nonsense like https://luduxia.com/showdown/ and https://luduxia.com/whichwayround/ . This is a experimental custom renderer with DoF, subsurface scattering and lots of other oddities. You are not killed by calculation but memory access, but how to reduce this in blur operations is well understood.
What there is not is semi transparent objects occluding each other, because this becomes a sorting nightmare and you would end up having to resolve a whole lot of dependencies on this dynamically. (Unless you do things with restricting blending modes). Implementing that in the context of widgets that move on a 2D plane with z-index sorting is enormously easier than in a 3D scene though.
That's really interesting. I wonder if you could achieve it by a combination of the glassmorphism effects on my page with some neuromorphism effects: https://www.justinmind.com/ui-design/neumorphism
With a quick google search, it looks like you can find some which mimic the 'coke bottle bottom' shape with shadow and light.
I extracted a similar "light rays" texture from Windows 7 when I was trying to replicate its aero glass effect on Android to see what can be done with the new shader APIs. I ended up with something very close to this article, except I didn't do the inner shadows but I did increase the saturation of the blurred background a bit.
Very cool. The light rays texture can actually do a lot of heavy lifting in the effect. TBH the one I made for the tutorial isn’t even that great. I like the harder lines on that Windows 7 one.
I thought about playing with saturation and I saw some other examples do that. I decided against it. For my article anyways it wouldn’t have mattered as much given that the moon image I used doesn’t have much color. I’d encourage folks making their own glass to play with that though.
This is great work, the interactive demo is a good way to show it off too. It’s fun to drag the window over the moon.
That said I dislike the use of frosted glass in user interface design, and feel it was a step backwards for Mac OS when it was added. Designers (hypocritically including myself - I use it too sometimes) are so seduced by it. But in practice it’s never ideal. Especially if the content behind the panel is dynamic or user generated.
It’s the brushed metal of the 2010s, I’m surprised that it leaked out of Windows Vista into everything else!
Why isn't it "ideal"? Visual design is mostly about personal preferences about what looks good, rather than serving any practical purpose. Yes, design also impacts functionality, but it mostly exists to make the user experience more pleasant.
If you ask me, skeuomorphism makes interfaces more pleasing to use than the minimalistic trend of the past decade+, where everything must be flat. It adds a visual flourish that replicates surfaces and materials we're used to from the real world, making interfaces more familiar and approachable. From a practical standpoint, flat design makes it hard to distinguish elements and their state, whereas when we had 3D buttons, brushed metal and frosted glass, this was very clear.
I think the pendulum is swinging back now, as more designers are shunning the flat look, so hopefully we'll see a resurgence of more human-friendly UIs.
I loved it but once I had to tail a live log of a Docker container with no option to install even 2-3 basic UNIX tools (like `tee` in order to append to a text log) and from that day and on I removed the 20% transparent background image.
Nowadays I have just one terminal program that is just slightly transparent and I have a nice desktop background that is fairly uniform and almost never gets in the way -- but I never use that one for my Neovim or for ssh-ing into remote machines. Only for myself fiddling around with stuff.
Transparency did look cool but once it prevents you from doing your job well once, it's out the door.
I'm not a UI designer so honest question: is the problem the use of aesthetics, like frosted glass or brushed metal, in UI design or is it that in pursuit of presenting such interfaces some designers lost the visual queues needed to indicate where controls are and what they do?
That's the reference. Brushed metal was a controversial design feature of early Mac OS X, unevenly applied across the built-in applications. (It was kind of supposed to be for media browsers, but then the Finder and Calendar and many others were also brushed metal for some reason.)
It debuted already in 1999 in QuickTime Player, years before Mac OS X:
The rumor was that Steve Jobs liked this style a lot, so it spread to the operating system despite the widespread external criticism (like the link above).
The floating window doesn't update for me past the initial position. Windows 10 19045.5131. Chrome is up to date Version 131.0.6778.86 (Official Build) (64-bit)
That is quite strange Chrome behavior. Seems to only update it's background position when the window size changes. Looks like a Chrome bug to me! Probably some optimization effort that went wrong. I'm quite sure that it worked back in the days in Chrome.
I took it one step further even earlier using a Flash file as a backdrop which was able to achieve the glass effect while still being in a dynamic moveable frame. Can't recall if it used iframes, would need to dig up the code but considering the era it probably did.
Cool technical achievement; Bad UX. It's harder to read or understand anything inside a translucent panel than one with a consistent, solid background because of lower and inconsistent contrast with the background. Additionally, things potentially happening underneath will be distracting and disorienting.
"Bad UX" can't be generalized that easily for a simple visual effect, that's highly dependent on the integration.
A good integration would:
- consider how heavily to use the effect to not overload the ui
- query for feature support to avoid adding all additional decorations if blur isn't available
- query for display & video features to avoid rendering the effect on devices that likely don't have a capable gpu
- query for user preferences and serve solid colors with good contrasts to users who might struggle with the busier background
- limit the extent of the effects and shadows depending on available space
- tweak the blurring and opacities to ensure good readability in the specific UI, regarding how complex or contrasted the background under blurred areas will be
- ensure blurs and shadows scale adaptively with the typography to ensure consistent visuals
UX is by definition the design of how a user experiences the complete app and interaction, it's not made or broken by individual stylistic choices
Eh, if lower contrast is an issue, make the background or glass tint darker, and the foreground content lighter, or viceversa. Good contrast is a challenge with any design element, regardless if it's using a solid color or this glass effect.
Things happening in the background being distracting and disorienting is also very subjective. You can lower the translucency of the glass just as you would lower the opacity of a solid color.
My point is that your criticism is far from being objectively true. There are ways of integrating this design element without running into those issues. The screenshot from the Forza game looks fine, for example, and having seen it in action, the background is not distracting. And what you gain is a more interesting and visually pleasing UI than if you were using a solid background. This may be more important in a video game, but it can also be done tastefully in OS and web design.
Forza is a game, the background being distracting or not isn't a real problem. On Windows 11 however there is some transparency effect here and there and it's indeed very annoying when a window change color because of what is behind it. Thankfully there's a setting to turn that down.
Yeah, I don’t use this effect across my site because it’s harder to get a good UX with it.
That being said, it has more of a place in games. Especially in HUD where you don’t want to occlude the background since that’s the main area a user is interacting.
Windows Vista solved this by giving black text on top of the frosted glass a white shadow-like outline. This guarantees the text is readable even in the extreme case where the background is black. In CSS this effect can be replicated with the text-shadow property.
You have to combine translucent panels with a 80-90% opaque background color if you want to have text on it. Then it's a subtle effect and the text is readable.
Agree. And when iOS started doing it years ago I was disappointed for that reason — loss of contrast. But also you just know there's a (significant?) battery cost to the effect.
False. The human brain and eye is built to recognize foreground and background and shift focus and attention based off of blur.
Thousands of years of adaptation has honed the brain and the eye to be optimized for this type of view much moreso then the simple UX you see here on HN.
Not only does the blurred/frosted glass background look better but it should be clearer because that's what we've been designed to do.
This holds true in 3D space to a _certain degree_, but here we’re looking at faux 3D projected onto a flat 2D surface where our eyes’ depth perception doesn’t work.
No we like photos with blur in the background. We prefer such photography. So who’s to say the faux surface fails?
Again we need evidence based measurements which the entire UX field lacks. It’s just a bunch of made up concepts strung together with little scientific research.
Do those articles use scientific evidence? Do they measure anything quantitative or is it just a bunch of opinion.
UX poses as a scientific field when really there is little evidence based research and it’s all just technical procedure and big words. Technical procedures are illusory they make you think it’s legit with a bunch of rules but to be scientific you need evidence. As technical as the rules are, a lot of it is made up bs.
UX design is one of those bs concepts that litter the world and poses as legitimate. It’s like the food pyramid from the USDA that says refined carbs are the most important part of every meal.
If the debate is on how much contrast then run some science. Instead UX just debates and as a result the entire field is made up conjecture.
Yes, our brain is good at this - but it still takes some capacity in processing to do this. I guess the point is: if you have a simple, high-contrast background - your brain needs less capacity to process it.
The human body is designed to desire and consume the maximum amount of feel good tasty food for maximum energy but we are finding that the evolution of the human body is not designed to actually accept such massive consumption despite our desire for such food. Our bodies do not handle the highest capacity consumption instead they have narrowly evolved to fill a strangely specific niche.
Same with our eyes. It may seem easier to like high contrast designs but our eyes through millions of years of evolution are not optimized for high contrast signs since those things never existed in nature.
Nice. I struggle though to compare the differences. I would find it easier to have one demo and a dropdown which I can select which example I'm looking at.
Interactive examples are nice, but would have been better if there was a side by comparison or toggle for switching to previous iteration. In most of the cases improvement of each iteration is so subtle I couldn't tell a difference.
physically wrong, as it only incorporates the pixels directly behind the glass. Noticeable with the upper few rows overexaggerating the cropped background pixels.
This results in flickering when vertically scrolling over abrupt BG color borders , eg noticeable on mobile browser Twitter UI
On a semi-related note, the best in-game UI I’ve ever seen was in Prey 2017. The little computers and terminals you interact with look amazing, and every single I time I used one I was spellbound. The huge amount of effort that goes into small details in games in particular is incredible.
I noticed the blur only "sees" the underlying pixels directly below the glass surface. Any pixels outside that box, but within the blur radius do not get used in the gaussian filter. Probably the edge pixels are just repeated. You can see this when the light of the moon pops in to view when the edge of the rectangle starts to touch the moon. It would look more real if the light pixels from the moon start to through even when the box itself is still just over the dark area.
Would this be possible to achieve in CSS? I presume having a larger box with the blur, but clipping it to a smaller box or something like that.
Do you like that subsurface scattering is really visible with a darker background? I can clearly see the circles of varying opacity in a step-like gradient, and I can clearly see the light rays static image. Is it something with my browser or how it renders the thing? I really like how it looked more before the "More subsurface scattering" came in.
Tbh I agree the final light steps can give it more of an arcade style and feel less realistic. I think if I used this effect widely I’d make a more professional light rays image with a different opacity. I’m not entirely sure I’d use the subsurface effects or not. If I did I may reduce their intensity.
One challenge with a demo like this is that subtle effects may look better, but they are harder to see. So I balanced making them visible enough to appreciate which is more intense than I’d otherwise want.
Little tip, you might want to add a -webkit-user-select: none on the container elements so it prevents highlighting in Safari when dragging the cursor out and back over.
Thanks for the tip! I had `user-select: none` on the container which had the glass inside of it but apparently that didn't work. I just updated the page with `user-select: none` on the glass itself and it looks like that did the job.
Yeah it's basically fine in Safari because mobile requires a double tap to highlight, but only a single click on desktop. So highlighting is more intentional on mobile than desktop.
I'm pretty sure there is no subsurface scattering in frosted glass. Indeed frosted glass is just regular glass with a frosted surface. Below the surface, it's just pure glass, which does not scatter light.
Tbh it’s more like an edge-lit acrylic effect. We did call it a “subsurface effect” when I worked at Forza but may have been using the term loosely. Forza also was going for acrylic rather than glass and we had several acrylic samples around the office to play with.
That being said my example is not acrylic… and it’s not quite glass either as you mention. It’s more like glass with some artistic license.
I agree that it looks nice and similar to what SSS eventually renders like. But strictly speaking it's not SSS. Actual SSS happens when the medium is somewhat transparent (light can enter the material) but also diffusive (light gets randomly bounced around within the material). Glass lacks this second property. A good example of a material exhibiting strong SSS would be wax.
Not that this matters much anyway, the effect is cool nonetheless, albeit a little bit improperly named.
I haven't done HTML or CSS since HTML4 and CSS2 were cutting edge. This kind of stuff blows my mind now. Very cool, too bad frontend is arcanine magic these days because I don't have time to learn all this anymore.
I feel like 90% of what he did was barely noticable. I did the core frosted glass look back in around 2012. I still think it is great and the contrast is fine if you do it right.
That link is not a box filter, as it still uses weights to approximate a gaussian convolution kernel. It just uses some special hardware to do less texture fetches. But that is a constant 2x improvement over the full 1D convolution, not the box filter O(1) approach that the article suggests that browsers are using.
It is the performance win for similar looking results that I find improbable. For a box blur to look like gaussian blur, you would need multiple passes. Even though each pass is now O(1) instead of O(n) (with n the blur radius), due to caching effects I think a gaussian kernel would still be faster, especially for the small blur radius as described in the article.
[OneJS](https://onejs.com/) for Unity is a more modern entry in this space (Disclaimer: I'm the creator). Instead of embedding a browser/webview, it lets you use web techs and directly integrates with UI Toolkit (Unity's native UI solution).
A general drawback of using web UIs in games is the lack of support for performant 2D vfx. It's something I'd like to tackle in 2025 with [Spark2D](https://github.com/Singtaa/Spark2D).
In my experience there are two kinds of games: UI is the game or UI supports the game. When UI is the game, the performance bottleneck is almost always text rendering. From a DX POV there are many solutions, but from a performance POV, how can anyone compete with Skia or the native text APIs?
I feel that no one can compete with Skia in terms of feature-richness. But performance, it'll really depend on the environment, hardware, and what you are doing.
Unity's UI Toolkit, for example, is mesh and shader-based, so it can be highly performant for complex UIs.
Interesting note: If you use OneJS with the NodeJS backend, you can use the wasm version of Skia and render all kinds of cool stuff onto a texture in Unity. Obviously the performance with that is not ideal for animation. But I was able to quickly and easily render music notations and charts on my deployed Unity app on Android using that method.
> Why not embedding a browser directly though? How do you feel about the Flutter based UI Widgets?
Mostly to avoid overheads on both disk space and runtime performance. QuickJS is only ~20MB to embed. And I have no experience with Flutter, unfortunately. =/
I was part of an investigation which considered Coherent products for one of the Forza titles. We didn't go with it at the time, and I haven't had the opportunity to use it on a title at other companies, but it looks rad.
Forza used a custom UI system based on XAML and the acrylic elements at the top of the article were largely implemented in a custom shader. For a custom system it was pretty solid. We also built a lot of tech into it related to 3D placement of elements to support diagetic UI.
I'm not seeing the "background-attachment fixed" working at all. Not the CSS and neither the JavaScript solution. The rays stay static, detached from the moving div just as they were before applying that code.
I have this almost everywhere on my KDE Plasma desktop, with the help of Kvantum* (their debian dependencies seem to be broken - I had to build it from source in a container). Maybe it won't last for long, but I absolutely love the aesthetics.
This has like 10 stacked effects, thats about 7 too many except for the most demanding aesthetics.
Just use the background color + blur + box shadow or border
For folks who wanted a less intensive glass effect, they could pick and choose from the tutorial. You get a pretty respectable piece of glass at step three with just blur and shadow. I'd personally recommend doing that and mixing in a static light ray image. IDT most applications would need the full JavaScript effect. It's fun but it can be distracting.
With blur, shadow, and light rays alone you can already get _really close_ to that Forza image at the top.
Did you miss the bit where the author explains that he is going for the most demanding aesthetics?
I really like the aestectics, even if physically wrong at the edges. Thanks for sharing the details.
As a embedded developer, I feel this is kind of wasteful. Every client computes an "expensive" blur filter, over an over again? Just for blending to a blurred version of the background image?
I know - this is using the GPU, this is optimized. In the end, this should not be much. (is it really?)
<rant> I feel the general trend with current web development is too much bloat. Simple sites take 5 seconds to load? Heavy lifting on the client? </rant>... but not the authors fault
I guess everybody has their own preconceptions of what's wasteful.
I grew up in the era of 14.4k modems, so I'm used to thinking that network bandwidth is many, many orders of magnitude more scarce and valuable than CPU time.
To me, it's wasteful to download an entire image over the Internet if you can easily compute it on the client.
Think about all the systems you're activating along the way to download that image: routers, servers, even a disk somewhere far away (if it's not cached on the server)... All that just to avoid one pass of processing on data you already had in RAM on the client.
I have the same perspective regarding bandwidth, but I also consider any client to be running on a computer at least ten years old and at least three OS revisions behind.
I like to consider myself a guest on a client CPU, GPU, and RAM. I should not eat all their food, leave an unflushed turd in their toilet, and hog the remote control. Be a thoughtful guest that encourages feelings of inviting me back in the future.
Load fast, even when cell coverage is marginal. Low memory so a system doesn't grind to a halt from swapping. Animate judiciously because it's polite. Good algorithms, because everyone notices when their cursor becomes jerky.
"Mips – processing cycles, computer power – had always been cheaper than bandwidth. The computers got cheaper by the week and the phone bills stayed high by the month." - The Star Fraction, 1995
each visitor brings their own cpu to do this work whereas the server bandwidth is finite
I'm confused though.
If the goal is to optimize for server bandwidth, wouldn't you still want to send the already-blurred photo? Surely that will be a smaller image size than the pre-blurred full res photo (while also reducing client-side CPU/OS requirements).
Okay but how do you compute an image? How would your browser -- or any other client software -- know what's the hero image of a blog that you never visited before, for example?
I feel like I am missing something important in your comment.
The article describes computational method of rendering frosted glass effect. You can achieve the same thing by rendering the effect once (then upload to a sever) and have client download the rendered image. Or you can compute the frosted glass effect. What's better? That's the argument.
Ah, sorry, I didn't make it as far in the article.
IMO it really depends on the numbers. I'd be OK if my client downloads 50KB extra data for the already-rendered image but I'll also agree that from 100KB and above it is kind of wasteful and should be computed.
With the modern computing devices we all have -- including 3rd world countries, where a cheap Android phone can still do a lot -- I'd say we should default to computation.
Most of those websites that are technically "wasteful" in some ways, are way more "wasteful" when you realize what we use them for. Mostly it's for pure entertainment.
So either entertainment is wasteful, or if it's not, spending more compute to make the entertainment better is OK.
I would say most websites are wasteful wrt the customer, which is usually advertisers. There are websites where the user is the customer, but they’re rare these days.
Isn't sending both the blurred and non-blurred picture over the network the way we did it since two decades in web dev? With (many!) high resolution pictures this is definetly less performant then a local computation, given that real networks have finite bandwiths, in particular mobile clients on spots with bad wireless coverage. It is astonishing what can be done with CSS/WebGL only these days. We needed a lot of hacks and workarounds in the past for that.
I don't have much data myself but when I was doing scraping some time ago I had thousands of examples where f.ex. the full-res image was something like 1.7MB and the blurred image was in the range of 70KB - 200KB, so more or less 7% - 11% of the original. And I might be lying here (it's been a while) but I believe at least 80% of the blurred images were 80KB or less.
Technically yes you could make some savings but since images were transferred over an HTTP-1.1 Keep-Alive connection, I don't feel it was such a waste.
Would love to get more data if you have it, it's just that from the limited work I did in the area it did not feel very worth of only downloading the high-res image and do the blur yourself... especially in scenarios when you just need the blurred image + dimensions first, in order to prevent the constant annoying visual reflow as images are downloaded -- something _many_ websites suffer from even today.
A blurred image shouldn't be very much extra over the high resolution image considering it's information content is much smaller.
As per the central limit theorem one can approximate Gaussian with a repeated convolution with any function, box blur being most obvious candidate here. And box blur can be computed quickly with a summed area table.
> a repeated convolution
I really wonder what's the field of reference of "quickly" there. To me convolution is one of the last resort techniques in signal processing given how expensive it is (O(size of input data * size of convolution kernel)). It's of course still much faster than gaussian blur which is still non-trivial to manage at a barely decent 120fps even on huge Nvidia GPUs but still.
I would argue that while it _feels_ wasteful to us humans, as we perceive it as a "big recomputation of the rendered graphics", technically it's not.
the redrawing of anything that changes in your ui requires gpu computation anyway, and some simple blur is quite efficient to add. Likely less expensive than any kind of animations of dom objects thar aren't optimized as gpu layers.
additionally, seeing how nowadays the most simple sites tend to load 1+ mb of JS and trackers galore, all eating at your cpu ressources, Id put that bit of blur for aesthetics very far down on the "wasteful" list
I guess eventually it's a trade-off between doing heavy lifting yourself and paying a little more compute and bandwidth, or offloading it to clients and wasting more energy but at lower cost to the developer. I think there are environmental arguments in both directions (more energy spent computing stuff on the client vs more energy sending pre-computed assets over the networks). I'm not sure which is better ultimately - I suppose it varies case-by-case.
First, I really like the effect the author has achieved. It's very pretty.
Now for a bit of whimsy. It's been said that a picture is worth a thousand words. However, a thousand words uses far less bandwidth. What if we go full-tilt down the energy saving path, replace some images with prose to describe them? What would articles and blog posts look like then?
I know it's not practical, and sending actual images saves a lot of time and effort over trying to describe them, but I like the idea of imagining what that kind of web might look like.
With a standardized diffusion model on the receiving end, and a starting point image (maybe 16x16 pixels) with a fixed seed, we could send images with tiny amounts of data, with the client deciding the resolution (deciding how much compute to dedicate) as well as whatever local flavor they wanted (display all images in the style of Monet…) bandwidth could be minimized and the user experience deeply customized.
We’d just be sending prompts lol. Styling , css, etc all could receive similar treatment, using a standardized code generating model and the prompt/seed that generates the desired code.
Just need to figure out how to feed code into a model and have it spit out the prompt and seed that would generate that code in its forward generation counterpart.
I’m pretty sure the radio on a mobile device consumes more energy than the GPU doing a 2D operation on a single image.
If you want to save energy, send less data.
Tbh I think people radically underestimate how fast, and efficiently so, GPUs are. The Apple Watch has physically based rendering in the UI. It would be curious to compare the actual cost of that versus using a microcontroller to update a framebuffer pushed to a display via SPI.
I did some webgl nonsense like https://luduxia.com/showdown/ and https://luduxia.com/whichwayround/ . This is a experimental custom renderer with DoF, subsurface scattering and lots of other oddities. You are not killed by calculation but memory access, but how to reduce this in blur operations is well understood.
What there is not is semi transparent objects occluding each other, because this becomes a sorting nightmare and you would end up having to resolve a whole lot of dependencies on this dynamically. (Unless you do things with restricting blending modes). Implementing that in the context of widgets that move on a 2D plane with z-index sorting is enormously easier than in a 3D scene though.
This is really cool and thanks for sharing the details. Now I want to see coke bottle glass effects. :-) https://www.nathanallan.com/product/bottle-base-textured-gla...
That's really interesting. I wonder if you could achieve it by a combination of the glassmorphism effects on my page with some neuromorphism effects: https://www.justinmind.com/ui-design/neumorphism
With a quick google search, it looks like you can find some which mimic the 'coke bottle bottom' shape with shadow and light.
I extracted a similar "light rays" texture from Windows 7 when I was trying to replicate its aero glass effect on Android to see what can be done with the new shader APIs. I ended up with something very close to this article, except I didn't do the inner shadows but I did increase the saturation of the blurred background a bit.
https://mastodon.social/@grishka/110524476584503201
Very cool. The light rays texture can actually do a lot of heavy lifting in the effect. TBH the one I made for the tutorial isn’t even that great. I like the harder lines on that Windows 7 one.
I thought about playing with saturation and I saw some other examples do that. I decided against it. For my article anyways it wouldn’t have mattered as much given that the moon image I used doesn’t have much color. I’d encourage folks making their own glass to play with that though.
This is great work, the interactive demo is a good way to show it off too. It’s fun to drag the window over the moon.
That said I dislike the use of frosted glass in user interface design, and feel it was a step backwards for Mac OS when it was added. Designers (hypocritically including myself - I use it too sometimes) are so seduced by it. But in practice it’s never ideal. Especially if the content behind the panel is dynamic or user generated.
It’s the brushed metal of the 2010s, I’m surprised that it leaked out of Windows Vista into everything else!
Why isn't it "ideal"? Visual design is mostly about personal preferences about what looks good, rather than serving any practical purpose. Yes, design also impacts functionality, but it mostly exists to make the user experience more pleasant.
If you ask me, skeuomorphism makes interfaces more pleasing to use than the minimalistic trend of the past decade+, where everything must be flat. It adds a visual flourish that replicates surfaces and materials we're used to from the real world, making interfaces more familiar and approachable. From a practical standpoint, flat design makes it hard to distinguish elements and their state, whereas when we had 3D buttons, brushed metal and frosted glass, this was very clear.
I think the pendulum is swinging back now, as more designers are shunning the flat look, so hopefully we'll see a resurgence of more human-friendly UIs.
My terminal windows have had a slight transparency for years, but now I've been rethinking it
I loved it but once I had to tail a live log of a Docker container with no option to install even 2-3 basic UNIX tools (like `tee` in order to append to a text log) and from that day and on I removed the 20% transparent background image.
Nowadays I have just one terminal program that is just slightly transparent and I have a nice desktop background that is fairly uniform and almost never gets in the way -- but I never use that one for my Neovim or for ssh-ing into remote machines. Only for myself fiddling around with stuff.
Transparency did look cool but once it prevents you from doing your job well once, it's out the door.
I'm not a UI designer so honest question: is the problem the use of aesthetics, like frosted glass or brushed metal, in UI design or is it that in pursuit of presenting such interfaces some designers lost the visual queues needed to indicate where controls are and what they do?
Ironically previous versions of macOS also used brushed metal heavily
That's the reference. Brushed metal was a controversial design feature of early Mac OS X, unevenly applied across the built-in applications. (It was kind of supposed to be for media browsers, but then the Finder and Calendar and many others were also brushed metal for some reason.)
It debuted already in 1999 in QuickTime Player, years before Mac OS X:
http://hallofshame.gp.co.at/qtime.htm
The rumor was that Steve Jobs liked this style a lot, so it spread to the operating system despite the widespread external criticism (like the link above).
Kind of interesting how we've come full circle. One of the original css demos (for css 1) was for a frosted glass effect https://meyerweb.com/eric/css/edge/complexspiral/glassy.html
I did a CSS experiment back in 2008 (before CSS allowed for backdrop-blur) that did the same'ish effect: https://webdev.andersriggelsen.dk/aero/
It works by using a fixed-position pre-blurred (with glass effects) background image: https://webdev.andersriggelsen.dk/aero/bgl.jpg
This is a lot more performant than a live gaussian blur but it of course has all the drawbacks of not allowing for a dynamic background image.
The floating window doesn't update for me past the initial position. Windows 10 19045.5131. Chrome is up to date Version 131.0.6778.86 (Official Build) (64-bit)
That is quite strange Chrome behavior. Seems to only update it's background position when the window size changes. Looks like a Chrome bug to me! Probably some optimization effort that went wrong. I'm quite sure that it worked back in the days in Chrome.
This works as expected in Firefox.
I took it one step further even earlier using a Flash file as a backdrop which was able to achieve the glass effect while still being in a dynamic moveable frame. Can't recall if it used iframes, would need to dig up the code but considering the era it probably did.
Cool technical achievement; Bad UX. It's harder to read or understand anything inside a translucent panel than one with a consistent, solid background because of lower and inconsistent contrast with the background. Additionally, things potentially happening underneath will be distracting and disorienting.
"Bad UX" can't be generalized that easily for a simple visual effect, that's highly dependent on the integration.
A good integration would:
- consider how heavily to use the effect to not overload the ui
- query for feature support to avoid adding all additional decorations if blur isn't available
- query for display & video features to avoid rendering the effect on devices that likely don't have a capable gpu
- query for user preferences and serve solid colors with good contrasts to users who might struggle with the busier background
- limit the extent of the effects and shadows depending on available space
- tweak the blurring and opacities to ensure good readability in the specific UI, regarding how complex or contrasted the background under blurred areas will be
- ensure blurs and shadows scale adaptively with the typography to ensure consistent visuals
UX is by definition the design of how a user experiences the complete app and interaction, it's not made or broken by individual stylistic choices
Eh, if lower contrast is an issue, make the background or glass tint darker, and the foreground content lighter, or viceversa. Good contrast is a challenge with any design element, regardless if it's using a solid color or this glass effect.
Things happening in the background being distracting and disorienting is also very subjective. You can lower the translucency of the glass just as you would lower the opacity of a solid color.
My point is that your criticism is far from being objectively true. There are ways of integrating this design element without running into those issues. The screenshot from the Forza game looks fine, for example, and having seen it in action, the background is not distracting. And what you gain is a more interesting and visually pleasing UI than if you were using a solid background. This may be more important in a video game, but it can also be done tastefully in OS and web design.
Forza is a game, the background being distracting or not isn't a real problem. On Windows 11 however there is some transparency effect here and there and it's indeed very annoying when a window change color because of what is behind it. Thankfully there's a setting to turn that down.
Yeah, I don’t use this effect across my site because it’s harder to get a good UX with it.
That being said, it has more of a place in games. Especially in HUD where you don’t want to occlude the background since that’s the main area a user is interacting.
It has all the same problems in games as it has on a website, it's just more acceptable to sacrifice usability for 'looking cool' in a game.
In HUD you don’t want to occlude the background since that’s the main area a user is interacting.
Windows Vista solved this by giving black text on top of the frosted glass a white shadow-like outline. This guarantees the text is readable even in the extreme case where the background is black. In CSS this effect can be replicated with the text-shadow property.
This is not my personal experience. It was very hard for me to read the text on vista glass.
You have to combine translucent panels with a 80-90% opaque background color if you want to have text on it. Then it's a subtle effect and the text is readable.
Agree. And when iOS started doing it years ago I was disappointed for that reason — loss of contrast. But also you just know there's a (significant?) battery cost to the effect.
It may be entirely done within the GPU, making the energy cost insignificant. At least apple added an accessibility setting to reduce the blur.
False. The human brain and eye is built to recognize foreground and background and shift focus and attention based off of blur.
Thousands of years of adaptation has honed the brain and the eye to be optimized for this type of view much moreso then the simple UX you see here on HN.
Not only does the blurred/frosted glass background look better but it should be clearer because that's what we've been designed to do.
This holds true in 3D space to a _certain degree_, but here we’re looking at faux 3D projected onto a flat 2D surface where our eyes’ depth perception doesn’t work.
No we like photos with blur in the background. We prefer such photography. So who’s to say the faux surface fails?
Again we need evidence based measurements which the entire UX field lacks. It’s just a bunch of made up concepts strung together with little scientific research.
I don't follow. What exactly has the brain been honed to do?
Every single article I've read on the matter says higher contrast is more readable. The debate is over how high is 'good enough'.
Do those articles use scientific evidence? Do they measure anything quantitative or is it just a bunch of opinion.
UX poses as a scientific field when really there is little evidence based research and it’s all just technical procedure and big words. Technical procedures are illusory they make you think it’s legit with a bunch of rules but to be scientific you need evidence. As technical as the rules are, a lot of it is made up bs.
UX design is one of those bs concepts that litter the world and poses as legitimate. It’s like the food pyramid from the USDA that says refined carbs are the most important part of every meal.
If the debate is on how much contrast then run some science. Instead UX just debates and as a result the entire field is made up conjecture.
Yes, our brain is good at this - but it still takes some capacity in processing to do this. I guess the point is: if you have a simple, high-contrast background - your brain needs less capacity to process it.
You got evidence to back that up?
The human body is designed to desire and consume the maximum amount of feel good tasty food for maximum energy but we are finding that the evolution of the human body is not designed to actually accept such massive consumption despite our desire for such food. Our bodies do not handle the highest capacity consumption instead they have narrowly evolved to fill a strangely specific niche.
Same with our eyes. It may seem easier to like high contrast designs but our eyes through millions of years of evolution are not optimized for high contrast signs since those things never existed in nature.
Nice. I struggle though to compare the differences. I would find it easier to have one demo and a dropdown which I can select which example I'm looking at.
This is good feedback. I considered putting each example side-by-side with the previous but it was too noisy.
I’ll think about it more this morning and see if I can come up with a UX for this that doesn’t interrupt the flow of the article as harshly.
perhaps just keep two glass tiles in each example, the old and new one.
But I'd be happy with a single one with all at the end :)
Interactive examples are nice, but would have been better if there was a side by comparison or toggle for switching to previous iteration. In most of the cases improvement of each iteration is so subtle I couldn't tell a difference.
Agreed, on mobile I can hardly tell the difference after the second step, if at all.
Same for me, I don’t see a single difference between the examples. I’ll try again later on my laptop and see if it changes anything.
The first example looks beautiful to me though, I might use it in my next UI.
I used a similar technique to create glass-like panels with my online timeline maker (https://www.chronoflotimeline.com). You can see an example timeline with glass-like panels here: https://www.chronoflotimeline.com/timeline/shared/3118/Home-...
Man this is cool... Is your lib opensource?
Not quite frosted, but I went for a glass pane effect on the sidebar at https://www.gyan.dev/ffmpeg/builds/
Your site is very relaxing and pretty on pc.
For real, I'm not a fan of flashy colors in websites and that palette looks very calming
physically wrong, as it only incorporates the pixels directly behind the glass. Noticeable with the upper few rows overexaggerating the cropped background pixels.
This results in flickering when vertically scrolling over abrupt BG color borders , eg noticeable on mobile browser Twitter UI
Yeah. I think Windows Vista didn't have that problem. I assume this can't be solved with CSS.
Looks awesome!!
On a semi-related note, the best in-game UI I’ve ever seen was in Prey 2017. The little computers and terminals you interact with look amazing, and every single I time I used one I was spellbound. The huge amount of effort that goes into small details in games in particular is incredible.
Author here! Happy to answer any questions.
Very nice effect. I love these more creative realistic elements.
This one reminds me of this cool card effect
https://poke-holo.simey.me/
Clicking around found this breakdown [1]. Expertly crafted but also really cool like the optical illusion background does a lot of the heavy lifting!
---
1: https://www.joshdance.com/100/day50/
Funny enough I also implemented the 3D cards in Forza Motorsport 7 :p
I noticed the blur only "sees" the underlying pixels directly below the glass surface. Any pixels outside that box, but within the blur radius do not get used in the gaussian filter. Probably the edge pixels are just repeated. You can see this when the light of the moon pops in to view when the edge of the rectangle starts to touch the moon. It would look more real if the light pixels from the moon start to through even when the box itself is still just over the dark area.
Would this be possible to achieve in CSS? I presume having a larger box with the blur, but clipping it to a smaller box or something like that.
Other folks made similar comments. I’ll have to see if this is possible. Your recommendation at the bottom sounds plausible so I’ll give it a go.
Do you like that subsurface scattering is really visible with a darker background? I can clearly see the circles of varying opacity in a step-like gradient, and I can clearly see the light rays static image. Is it something with my browser or how it renders the thing? I really like how it looked more before the "More subsurface scattering" came in.
Tbh I agree the final light steps can give it more of an arcade style and feel less realistic. I think if I used this effect widely I’d make a more professional light rays image with a different opacity. I’m not entirely sure I’d use the subsurface effects or not. If I did I may reduce their intensity.
One challenge with a demo like this is that subtle effects may look better, but they are harder to see. So I balanced making them visible enough to appreciate which is more intense than I’d otherwise want.
Very cool stuff!
Little tip, you might want to add a -webkit-user-select: none on the container elements so it prevents highlighting in Safari when dragging the cursor out and back over.
Thanks for the tip! I had `user-select: none` on the container which had the glass inside of it but apparently that didn't work. I just updated the page with `user-select: none` on the glass itself and it looks like that did the job.
I may be mistaken, but I think you have to use the -webkit- prefix for it to work in Safari.
It's working great in Chrome and Firefox though.
Interesting, I'll add the prefix and install desktop Safari in the future.
I was testing on Safari iOS and it looks like the non-prefix version worked there.
Safari is only available on macOS
You must mean something by this. What do you mean?
// Written from a browser Apple calls Safari on iOS.
Yeah it's basically fine in Safari because mobile requires a double tap to highlight, but only a single click on desktop. So highlighting is more intentional on mobile than desktop.
I'm pretty sure there is no subsurface scattering in frosted glass. Indeed frosted glass is just regular glass with a frosted surface. Below the surface, it's just pure glass, which does not scatter light.
Tbh it’s more like an edge-lit acrylic effect. We did call it a “subsurface effect” when I worked at Forza but may have been using the term loosely. Forza also was going for acrylic rather than glass and we had several acrylic samples around the office to play with.
That being said my example is not acrylic… and it’s not quite glass either as you mention. It’s more like glass with some artistic license.
I agree that it looks nice and similar to what SSS eventually renders like. But strictly speaking it's not SSS. Actual SSS happens when the medium is somewhat transparent (light can enter the material) but also diffusive (light gets randomly bounced around within the material). Glass lacks this second property. A good example of a material exhibiting strong SSS would be wax.
Not that this matters much anyway, the effect is cool nonetheless, albeit a little bit improperly named.
If both sides are frosted, then you will have a similar effect as subsurface scattering.
Yes, it looks similar. But it's still not sub surface scattering.
Light inside the frosted glass just goes in a straight direction. It will not behave like this : https://blendamator.com/wp-content/uploads/2023/09/schema-ra...
Great inspiration, thanks. Been working on something that has gamified elements, and the pin has dropped that this style might be perfect
I haven't done HTML or CSS since HTML4 and CSS2 were cutting edge. This kind of stuff blows my mind now. Very cool, too bad frontend is arcanine magic these days because I don't have time to learn all this anymore.
I feel like 90% of what he did was barely noticable. I did the core frosted glass look back in around 2012. I still think it is great and the contrast is fine if you do it right.
I always feel rendering such blurred panes takes quite a performance hit. Do we have any numbers on this?
I might just be old - when this was done on the CPU.
Do browsers really use a box filter to approximate a gaussian blur? That seems implausible to me, as they produce pretty different looking blurs.
Yeah because the GPU has special hardware which you can take advantage of for an optimized box filter.
https://www.rastergrid.com/blog/2010/09/efficient-gaussian-b...
That link is not a box filter, as it still uses weights to approximate a gaussian convolution kernel. It just uses some special hardware to do less texture fetches. But that is a constant 2x improvement over the full 1D convolution, not the box filter O(1) approach that the article suggests that browsers are using.
It doesn't seem improbable considering it's a huge performance win and perhaps many won't notice?
It is the performance win for similar looking results that I find improbable. For a box blur to look like gaussian blur, you would need multiple passes. Even though each pass is now O(1) instead of O(n) (with n the blur radius), due to caching effects I think a gaussian kernel would still be faster, especially for the small blur radius as described in the article.
Many game UIs are built using HTML/CSS under the hood, so it has come full circle!
https://coherent-labs.com/products/coherent-gameface/
[OneJS](https://onejs.com/) for Unity is a more modern entry in this space (Disclaimer: I'm the creator). Instead of embedding a browser/webview, it lets you use web techs and directly integrates with UI Toolkit (Unity's native UI solution).
A general drawback of using web UIs in games is the lack of support for performant 2D vfx. It's something I'd like to tackle in 2025 with [Spark2D](https://github.com/Singtaa/Spark2D).
This is intriguing.
Why not embedding a browser directly though?
How do you feel about the Flutter based UI Widgets? (https://github.com/UIWidgets/com.unity.uiwidgets)
In my experience there are two kinds of games: UI is the game or UI supports the game. When UI is the game, the performance bottleneck is almost always text rendering. From a DX POV there are many solutions, but from a performance POV, how can anyone compete with Skia or the native text APIs?
I feel that no one can compete with Skia in terms of feature-richness. But performance, it'll really depend on the environment, hardware, and what you are doing.
Unity's UI Toolkit, for example, is mesh and shader-based, so it can be highly performant for complex UIs.
Interesting note: If you use OneJS with the NodeJS backend, you can use the wasm version of Skia and render all kinds of cool stuff onto a texture in Unity. Obviously the performance with that is not ideal for animation. But I was able to quickly and easily render music notations and charts on my deployed Unity app on Android using that method.
> Why not embedding a browser directly though? How do you feel about the Flutter based UI Widgets?
Mostly to avoid overheads on both disk space and runtime performance. QuickJS is only ~20MB to embed. And I have no experience with Flutter, unfortunately. =/
I was part of an investigation which considered Coherent products for one of the Forza titles. We didn't go with it at the time, and I haven't had the opportunity to use it on a title at other companies, but it looks rad.
Forza used a custom UI system based on XAML and the acrylic elements at the top of the article were largely implemented in a custom shader. For a custom system it was pretty solid. We also built a lot of tech into it related to 3D placement of elements to support diagetic UI.
Was this the in-house c++ WPF implementation?
Yes it was! I actually loved that thing.
Lots of games used to use [Scaleform](https://en.m.wikipedia.org/wiki/Scaleform_GFx) for their UI.
Lots of games still use it but its been discontinued by Autodesk and is on its way out. Not to mention Flash also being discontinued.
Including Minecraft (Bedrock / consoles) :)
https://www.youtube.com/watch?v=BnTUmksfRJU
The ones that don't are also interesting, like baldurs gate 3 uses this:
https://www.noesisengine.com/
Just so you know...
I'm not seeing the "background-attachment fixed" working at all. Not the CSS and neither the JavaScript solution. The rays stay static, detached from the moving div just as they were before applying that code.
In both Firefox and Vivaldi, on Windows.
I have this almost everywhere on my KDE Plasma desktop, with the help of Kvantum* (their debian dependencies seem to be broken - I had to build it from source in a container). Maybe it won't last for long, but I absolutely love the aesthetics.
* https://github.com/tsujan/Kvantum
Nice effect, nice article too
i have created a library for generating frosted glass effect, this looks so good on icons.
https://github.com/JP1016/react-icon-blur
Beautiful. And excellent writing!
Aw. Kind of like Windows 7 Aero theme.