port to SDL3 by notimaginative · Pull Request #7220 · scp-fs2open/fs2open.github.com

notimaginative · 2026-02-12T23:15:13Z

Basic port from SDL2 to SDL3. Also updates imgui to 1.92.5.

notimaginative · 2026-02-12T23:18:23Z

This is the basic port, and other SDL3-related feature PRs will come after this is merged.

One notable issue is that setting of gamma needs to be done by shaders as the gamma feature was removed from SDL3. Someone with a much better understanding of the current graphics code, and shaders in particular, should probably take care of that.

wookieejedi · 2026-03-05T20:15:34Z

@BMagnu is the Gamma shader aspect mentioned above something that you would be willing to comment on?

wookieejedi · 2026-03-24T14:31:36Z

If I start in windowed mode, then switch to fullscreen mode the screen flickers. It contines to flicker if in fullscreen mode upon game restart as well. This does not happen via windowed mode, so it is likely that the SDL 3 PR inadvertently reverted a bug fix we have in master for this screen flickering
Possibly to PR #6767 or related ones

notimaginative · 2026-03-24T15:17:01Z

If I start in windowed mode, then switch to fullscreen mode the screen flickers. It contines to flicker if in fullscreen mode upon game restart as well. This does not happen via windowed mode, so it is likely that the SDL 3 PR inadvertently reverted a bug fix we have in master for this screen flickering Possibly to PR #6767 or related ones

I don't remember seeing this, but I rarely use fullscreen mode. Or it simply might not happen on Mac. I'll check it out when I get the chance.

PR #6767 is still in there however, and wasn't altered for the port.

wookieejedi · 2026-03-24T15:21:19Z

Oh indeed, hmm yeah it's odd. At the very least it is always reproducible for me, so happy to do any local testing on Windows as we might need.

notimaginative · 2026-03-25T20:44:45Z

Squashed in fixes for the fullscreen bug as well as disabling the changing of display resolution at runtime. Both commits are available individually as part of #6735 for anyone that would like to see them without all the rest of the changes.

Basic port from SDL2 to SDL3. Also updates imgui to 1.92.5.

JohnAFernandez · 2026-05-20T16:31:29Z

 	}

-	OnMouseWheelHook->run(scripting::hook_param_list(scripting::hook_param("MouseWheelY", 'i', y), scripting::hook_param("MouseWheelX", 'i', x)));
+	OnMouseWheelHook->run(scripting::hook_param_list(scripting::hook_param("MouseWheelY", 'i', static_cast<int>(y)), scripting::hook_param("MouseWheelX", 'i', static_cast<int>(x))));


Wait, why did this type change? It looked like the type was irrelevant, but maybe I'm missing something.

SDL uses floats instead of ints now for those events. So I updated the functions used for events to take floats, but didn't want to mess with the types for a number of the global variables due to the amount of changes it tends to require. Leaving it for a future update instead.

And here in particular I wasn't sure if the scripting stuff would actually work the same if I sent the float directly so I just cast it to int like it was originally for safety.

@notimaginative Internally, Lua 5.1 uses floats for everything, including integers. So in that sense, changing from int to float here may work just fine. Though I'd like to have @BMagnu 's input as well.

Should likely be fine, but really, just keeping it as implemented with the static_cast is safest and doesn't diminish functionality at all, so I'd just keep it.

JohnAFernandez · 2026-05-21T23:07:32Z

-		vals.push_back(i);
+	// a display id of zero is invalid in SDL3 but we need to support older
+	// builds so reduce by 1 and hope it works out
+	return json_pack("i", static_cast<int>(value)-1);


Are there any other options for this? Sounds risky

In hindsight that comment wasn't appropriate. It's referring to new behavior in SDL3 where it doesn't reuse IDs during a session. For instance, if you have two monitors attached when FSO starts then SDL3 will assign them IDs of 1 and 2. If you disconnect the monitor with ID 1 and reconnect it while FSO is running then SDL3 assigns it a new ID of 3. So when FSO started it had two monitors with IDs of 1 and 2. Later those same two monitors have IDs of 2 and 3, where ID 3 refers to the monitor that used to be ID 1. If you update settings afterwards then the order of the monitors has now changed when FSO next loads.

So the "hope it works out" is referring to the likelihood that monitors would be connected, removed, or reconnected while FSO is running and hoping that it either doesn't ever happen or happens so infrequently that no one notices the issue. Not smart, true, but I considered the workarounds (like caching the device list for the duration of the game so it's always the same) to be properly dumb.

Basically IDs shouldn't be used to reference anything between sessions. It was that way in SDL2 as well, but IDs and indexes got used to reference devices because SDL2 maintained a fairly consistent list order (a hold-over from bad SDL1 design). SDL3 dropped that bad behavior.

The proper way to deal with it (even in SDL2, honestly) is to use device names as reference. That's something I'd like to address, but it means breaking compatibility with older builds, which isn't something I was prepared to do here. (That's better suited to it's own discussion, issue, and PR)

Got it. Sounds like we need to create three issues as follow ups to this - Mobile DPI, Gamma, and Monitor Referencing. Thanks for looking through everything I mentioned!

This issue here isn't specific to monitors though, it's all devices. Joysticks are another big one that required a bit of nuance, since they are referenced by index, but they're also referenced by GUID which allowed me to deal with it better (the joystick code now ignores the index and/or sets it to -1). Though I would like to change it to use both device name and GUID for joysticks at some point when/if we can agree to break config compatibility.

But gamma definitely does need a separate issue so that a graphics coder can tackle it.

I'll go ahead make them.

I am still planning to update that comment as well, just haven't gotten to it yet.

JohnAFernandez

That's my stuff handled. Thanks for taking the time to handle it!

notimaginative added this to the Release 26.0 milestone Feb 12, 2026

notimaginative requested a review from z64555 as a code owner February 12, 2026 23:15

wookieejedi added the refactor A cleanup/restructure of a feature for speed, simplicity, and/or maintainability label Feb 13, 2026

notimaginative force-pushed the sdl3_port branch 2 times, most recently from 3184bad to 37618ee Compare March 25, 2026 20:41

notimaginative force-pushed the sdl3_port branch from 37618ee to de41772 Compare March 26, 2026 04:16

port to SDL3

0c37ba8

Basic port from SDL2 to SDL3. Also updates imgui to 1.92.5.

notimaginative force-pushed the sdl3_port branch from de41772 to 0c37ba8 Compare May 11, 2026 11:45

notimaginative modified the milestones: Release 26.0, Release 26.2 May 21, 2026

JohnAFernandez requested changes May 27, 2026

View reviewed changes

This was referenced May 27, 2026

SDL3 Requires Better Device References To Avoid Buggy Behavior (Name instead of index) #7481

Open

SDL3 Requires new Gamma Shaders #7482

Open

handle DPI scaling for mobile in PPI check

85de932

JohnAFernandez approved these changes May 28, 2026

View reviewed changes

BMagnu added the Waiting for Stable Marks a pull request that is to be merged after the next stable release, due to a release cycle label May 31, 2026

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notimaginative commented Feb 12, 2026 •

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