Translated backend from SDL2 to SDL3

[dovker]

SDL 3 Backend

I literally just today wanted to update my engine to SDL3 and found that ImGui backend no longer works, therefore I translated the backend according to SDL3 rules, and as far as I've tested things, everything seems to work.

Screenshots:

[ocornut]

Hello. Thanks for the PR.
Since the code is so similar i think it should be kept in the same existing file so we don’t need to maintain two backends.

EDIT my bad, more changes than I saw at first glance.

[ocornut]

Also it seems like you copied the file but also based your work on a very old version of the SDL2 backend. We unfortunately cannot make use of any of it. You would need to start from latest version and make change in the same file.

Thank you.
EDIT used as reference when re-porting latest backend.

[dovker]

Also it seems like you copied the file but also based your work on a very old version of the SDL2 backend. We unfortunately cannot make use of any of it. You would need to start from latest version and make change in the same file.

Thank you.

Yeah, I just now realised that it's an old backend. I could translate the current SDL backend to SDL3, since I still need it myself and could be of some use to others.

The question now becomes, how do I fit both SDL2 and SDL3 backends in the same file, since a lot of enums and functions were updated in the 3.0 version. Should I use some sort of a macro for that, such as IMGUI_SDL_3?

[ocornut]

I don’t have an answer to your question since I don’t know what has changed yet, since we don’t have a diff. I’ll investigate later.

[ocornut]

I don’t have an answer to your question since I don’t know what has changed yet, since we don’t have a diff. I’ll investigate later.

Looks like more than I expected has changed. I'll be taking over this, thanks for the base PR!

[dovker]

No problem! (Should I close this PR?, I don't know how this works haha)

[ocornut]

I close when done, i just want to check if some of the workarounds for older SDL may be removed/simplified now.

[ocornut]

Tangential: pushed 6e976e5 to rename everything from "sdl" to "sdl2" in filenames that didn't have that previously.

[ocornut]

• 6e976e5 Rename everything from "sdl" to "sdl2" in filenames that didn't have that previously.
• e816bc6 Merge misc changes from docking branch to reduce small drift. (before forking)
• d9bf80f Backends: SDL3: copied imgui_impl_sdl2 into imgui_impl_sdl3 and ONLY replaced strings: NO OTHER CHANGES. This WILL NOT compile with SDL3. This intermediate commit designed to make it easier to visualize the meaningful changes in the next commit.
• 13fbd99 Backends: SDL3: update to run with SDL3. simplify where possible. + Examples: Add SDL3+Gl example.
• e4233c6 Merge.
• a526ff8: Backends: SDL3: Added multi-viewports support.

I can see a new issue that SDL2 backend didn't have: newly created and destroyed Windows are now subject to a very short appear/disappear "animation" in Windows 11, which didn't happen with the SDL2. It makes dragging backends feel quite bad.
I haven't yet investigated which change in SDL is causing this.

It's something somewhere in
https://github.com/libsdl-org/SDL/tree/main/src/video/windows
My first intuition was that it was caused by this change
libsdl-org/SDL@b4ebb3b
But trying to revert it didn't fix the issue for me.

Closing this as merged but I expect SDL3 backend to require further changes.

[ocornut]

My first intuition was that it was caused by this change
libsdl-org/SDL@b4ebb3b
But trying to revert it didn't fix the issue for me.

My bad, it IS exactly this commit (my build scripts weren't setup ideally for SDL3 and my mod wasn't reflected when I attempted the change. I will open an issue on SDL3 repo.

[ocornut]

Posted libsdl-org/SDL#6659 (comment)