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Comment by TheNewAndy | Hacker News Reader

One thing that is surprisingly slow on the M1 is running an OpenGL ES application in the simulator.

I developed a game on a shoestring budget, and hoped that an M1 would be able to be used for capturing video of the game at the resolutions that Apple wants, but it was way too slow to be able to do this, so I had to just leave video out of my store page.

The same app run on your M1 mac with its iOS compatibility works completely fine (as it should, it is a 2d game with about 10 sprites that just get drawn with scaling and no rotation).

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I've tried a number of games from the app store (relatively simple 2D games which don't melt your phone) on an M1 Pro MBP, and found they all constantly maxed out multiple CPU cores for no apparent reason.

There's definitely something wrong even with the iOS compatibility layer.

There is no OpenGL driver on M1. So your app is running through a translation layer to the native Metal driver underneath. All OpenGL rendering on M1, no matter the framework (iOS, Catalyst, macOS) has pretty terrible performance because of that.

Is this true for WebGL as well or does Safari/Chrome/Firefox do something special?

All browsers use the ANGLE library to translate to the underlying platform 3d engine (Direct3d, Metal, OpenGL, Vulkan?)

That aside, afaik M1 Macs only have OpenGL as a translation layer (to metal) for programs running under Rosetta

Simulator has never supported hardware acceleration for OpenGL ES. It is no different on an Intel Mac. Only Metal in Simulator runs on the GPU. This includes WebGPU if you're using Safari.

Sounds like it went through the software rendering path...

You are correct. It is frustrating because clearly it can be hardware accelerated, just Apple hasn't really bothered themselves to do this

I was under the impression that OpenGL on M1 devices just passes through to Metal at this point.

Does OpenGL ES not get this treatment...?

My guess is that they haven’t wired the iOS Simulator to use the M1’s hardware acceleration. I’m pretty sure WebGL (which uses OpenGL ES) is hardware accelerated on M1.

And iOS apps not running within the Simulator have hardware accelerated OpenGL ES too.

Simulator support for GPU rendering is far from trivial so it isn't about "bothering". Metal jobs are packaged up along with shaders and proxied out to the host macOS Metal framework. Textures are backed by IOSurfaces which do some fancy Mach memory mapping tricks to share memory between your app in a simulator, the macOS side of Metal, and sometimes GPU memory (on Intel Macs with discrete GPUs). For the most part this is transparent to you and works even when Simulator vNext is running on macOS vPrevious.

The vast majority of developers are using higher-level system frameworks, an engine that has a Metal renderer already, use WebGPU, or use Metal on Apple platforms.

With the amount of cash apple has, it very much is about bothering. They have the resources to make their development tools not terrible, but instead they seem to be investing in... cash for a rainy day.

Maybe they plan to bring an M1 iPhone to market, so it's not worth the considerable engineering effort to fix a problem that will go away by itself in a while.

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