ebiten: disabling vsync doesn't work on macOS

[venning]

Ebitengine Version

v2.9.0

Operating System

• Windows
• macOS
• Linux
• FreeBSD
• OpenBSD
• Android
• iOS
• Nintendo Switch
• PlayStation 5
• Xbox
• Web Browsers

Go Version (go version)

go version go1.26.0 darwin/arm64

What steps will reproduce the problem?

I have two monitors: a laptop monitor at 120 Hz and an external monitor at 60 Hz.

When the external monitor is not connected, Ebitengine runs at 120 FPS on the laptop monitor.

When the external monitor is connected, Ebitengine runs at 60 FPS on both monitors.

Additionally, ebiten.SetVsyncEnabled(false) does not go above 60 FPS.

What is the expected result?

Previously, for Ebitengine v2.8.9 and earlier: Ebitengine ran at 120 FPS on the laptop and 60 FPS on the external, always.

This was true whether connected or disconnected; starting the window on either monitor; or dragging the window between monitors.

Also, ebiten.SetVsyncEnabled(false) would cause Ebitengine to be much greater than 120 FPS on the laptop monitor.

What happens instead?

I have tracked this to a regression from Ebitengine v2.8.9 -> v2.9.0. I'm sorry for being late to upgrade and notice this. (Ebitengine v2.9.8 has the same problem.)

Anything else you feel useful to add?

MacBook M1 Pro (14-inch, 2021)
macOS Ventura 13.1

[hajimehoshi]

As of 2.9, Ebitengine use CAMetalDisplayLink and Ebitengine just follows it. So, I don't think this is a fixable issue.

[venning]

Oh, hmm. Does this mean that ebiten.SetVsyncEnabled() is no longer functional on macOS?

That is a rather helpful toggle in development. I occasionally disable Vsync to see if I have recently introduced a major performance regression.

For example, if I expect that I normally manage 250 FPS with Vsync disabled, but now I'm seeing 160 FPS, I know I need to investigate what I did. But if I can never go above 120 FPS (which, I guess, now requires disconnecting the external monitor), then I can't see regressions until they get bad enough to drop below 120 FPS; which would presumably represent many problems that have accumulated over time. This has been kind of important a couple of times already.

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EDIT Okay, I see that I can still use ebiten.GraphicsLibraryOpenGL to force OpenGL, and everything behaves as expected. Is that something I should be doing in production?

I'm sorry, I do understand that Mac development is difficult and am very appreciative of you making all of this work so well.

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EDIT Well, I may have spoken too soon. OpenGL doesn't work quite right on the external monitor. It tries to force 120 FPS, which it can sometimes do and sometimes not, depending on what's going on in the game.

I am completely okay with manually choosing Metal for the external monitor (where I do most development) and OpenGL when testing on the laptop monitor.

[hajimehoshi]

Oh, hmm. Does this mean that ebiten.SetVsyncEnabled() is no longer functional on macOS?

Disabling vsync should be possible. I'll take a look later.