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Comment by dabinat | Hacker News Reader

It’s technically impressive that they’re simulating the way light travels through glass. But a lot of the time it’s so subtle that I wonder if they could have just used simple semi-opacity and it would have had 85% of the same effect at a fraction of the CPU cycles.

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I seriously doubt they're doing anything more than a boring shader with some decent approximation.

We can stimulate light, but that's just a waste of ray tracing and introducing annoying complexities.

They probably do because the effect can be pretty closely recreated with a displacement map in SVG.

I agree. Actual simulation would be an inexcusable waste of resources when the end result is simply indistinguishable from a normal distortion filer. Specially when their newest flagship has a smaller battery.

If you assume a fixed depth “behind” the screen and a fixed eye position, a lot of the math shakes out. It’s overkill for button backgrounds, but the actual implementation of a simplified simulation isn’t as computationally heavy as I think you’re imaging.

I feel like this is a big miss for them. Am I really supposed to believe that the company making its flagship phones burn at 14W to simulate the travel of light through glass for a UI actually cares about the planet?

I strongly suspect (as I’ve said elsewhere) that there’s no simulation going on, just a bunch of precomputed refraction maps. Two dependent texture fetches are not nothing (and neither of course is the sequentializing nature of rendering a transparent thing over another thing), but I wouldn’t lose sleep over them if there was a point. Thus far I’m not convinced that there is.

Has noöne located and disassembled the thing yet? The speculation is getting tiresome. (I don’t own an up-to-date macOS device and have never owned an iOS one, so no help from my end, sorry.)

Ain't no way precomputed reflection maps are burning through the full TDP of the processor. Even the desktop experience is miserable perf-wise

For those who hasn’t seen it, just dropping down the control center consumes 14 watts of CPU/GPU power as demonstrated by various YouTube videos.

I'm not sure how but it doesn't seem to use that much processing power. My 5 year old apple watch seems to render the glass UI fairly well and I assume this thing has the bare minimum processing power.

It's a GPU shader(s), so you'd have to measure its resource usage indirectly (device heating up; shorter battery life).

iOS has been applying a gaussian blur to various UI layers for years so there likely isn’t a big incremental performance hit for this graphical effect

Why do you insist that the Watch uses the same exact code to render the glass?

Yes but that wouldn't slow down their older devices enough to make people buy new ones

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