feat(input): Implement SDL3 input and window management by githubawn · Pull Request #2639 · TheSuperHackers/GeneralsGameCode

githubawn · 2026-04-20T14:56:39Z

SDL3 Input Backend
This PR implements an SDL3-based input and windowing backend as a modern alternative to DirectInput and Win32 window creation. By utilizing SDL3, we bypass DirectInput emulation layers on modern systems, providing a lower-latency pipeline for Windows 11 and Wine/Linux users.

Input handling
Unified event manager that centralizes keyboard, mouse, and gamepad events into a thread-safe buffer

Gamepad Support (v0.1)
This is an initial baseline implementation focused on providing functional out-of-the-box playability. Feedback is encouraged regarding the ergonomics and logic of these default mappings.

Input	Action
Left Stick	Virtual mouse cursor
Right Stick	Camera pan (arrow keys)
LT (hold)	Currently unmapped
RT (hold)	Force Attack (LCTRL)
LB	Select All (Q)
RB	Queue Orders (LSHIFT)
A	Left click
AA	Guard mode
B	Right click
X	Attack Move (A)
Y	Stop (S)
D-Pad	Control groups 1–4
Start	Menu (ESC)
Back	Last radar event (SPACE)
L3	Next idle worker
R3	Snap to command center

Scope Note: This implementation provides a hardcoded default layout to establish core functionality. Advanced features, such as input remapping, radial menus, adjustable deadzones, are currently out of scope for this PR and may be addressed in future iterations.

The foundation of this backend was built using the SDL3 input work from the generalsX fork by fbraz3.

todo:
properly attribute all forks that have inspired this.

greptile-apps · 2026-04-20T15:05:09Z

Greptile Summary

Adds an SDL3-based window and unified input backend.

Introduces SDL3 keyboard, mouse, cursor, gamepad, text-input, and event-loop integration.
Adds SDL3-aware engine bootstrap and build configuration for Generals and Zero Hour.
Updates SDL3 and SDL3-image dependency declarations and platform configuration.

Confidence Score: 4/5

The PR is not yet safe to merge because high-DPI or logically scaled windows can map mouse and gamepad input to incorrect in-game positions.

Input coordinates are scaled using pixel framebuffer dimensions even though the SDL event and mouse-state coordinates are in the logical window coordinate space.

Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp

Important Files Changed

Filename	Overview
Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp	Implements unified SDL3 input and gamepad synthesis, but coordinate scaling mixes SDL logical coordinates with pixel window dimensions.
Core/GameEngineDevice/Source/SDL3Device/Common/SDL3GameEngine.cpp	Integrates SDL event polling, text input, minimized-window handling, and unconditional base-engine initialization.
Core/Main/SDL3Main.cpp	Adds SDL3 startup, window creation, failure cleanup, and application bootstrap.
Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Cursor.cpp	Delegates animated cursor frame management to SDL3 and bounds cursor-direction resource lookups.
cmake/sdl3.cmake	Adds conditional SDL3 and SDL3-image dependency resolution.
vcpkg.json	Declares the SDL3 dependency versions used by vcpkg builds.

Sequence Diagram

sequenceDiagram
    participant SDL as SDL3
    participant Manager as SDL3InputManager
    participant Mouse as SDL3Mouse
    participant Engine as GameEngine
    SDL->>Manager: Poll keyboard, mouse, gamepad, and window events
    Manager->>Mouse: Buffer mouse and synthetic gamepad events
    Manager->>Engine: Forward keyboard, text, and quit state
    Mouse->>Mouse: Translate and scale coordinates
    Engine->>Engine: Process game input and update frame

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp:355
**Logical coordinates use pixel scaling**

When SDL uses high-DPI or logical window scaling, mouse events and gamepad-generated events provide logical coordinates, but `scaleMouseCoordinates` scales them using pixel framebuffer dimensions. This coordinate-space mismatch maps cursor positions and clicks to the wrong in-game location.

_{Reviews (32): Last reviewed commit: "fix(sdl3): address PR review feedback on..." | Re-trigger Greptile}

stephanmeesters · 2026-04-20T18:22:52Z

+
+namespace {
+
+Bool DecodeNextUtf8Codepoint(const char* text, size_t length, size_t& offset, UnsignedInt& outCodepoint)


Do we need this, maybe better placed in UnicodeString? Or some other helper if it's generic stuff

Good point.

I looked at #2045 and #2528 which are working on UTF-8 infrastructure.
If one of those lands first, forwardTextInputEvent could use the bulk Utf8_To_Utf16Le conversion and iterate the resulting wchar_t string directly, making this function unnecessary.

Happy to refactor once there's a clear winner between those two. For now it's self-contained here.

xezon

This needs polishing. Not yet reviewed extensively until the obvious style issues are fixed.

xezon · 2026-05-05T19:48:02Z

+
+namespace {
+
+Bool DecodeNextUtf8Codepoint(const char* text, size_t length, size_t& offset, UnsignedInt& outCodepoint)


This function looks out of place. Bobtista was also working on Utf8 decoding in another change. It would be good to have this as a utility somewhere accessible engine wide, and not specific to this file.

Once #2528 lands I will migrate this.

xezon · 2026-05-12T22:32:25Z

Perhaps also check Fighter19's fork for SDL related implementations. As far as I am aware he has it all done.

githubawn · 2026-05-14T15:08:35Z

I have looked at all existing forks and attributed where possible.

bobtista · 2026-06-03T10:06:40Z

How about changing display-mode? eg getDisplayModeCount() / getDisplayModeDescription() using SDL_GetFullscreenDisplayModes + desktop mode + resolution filtering. EDIT: Also account for mouse position which can sometimes not match clicks to cursor position.

bobtista · 2026-06-03T10:10:47Z

Is it better to use SDL3InputManager (+ SDL3CursorManager) or to split out SDL3Keyboard + SDL3Mouse that subclass the engine's existing Keyboard/Mouse base classes?

xezon

Will we have a SDL3Main or not?

githubawn · 2026-06-14T23:09:12Z

I've started cleaning up the style and structural issues in the latest commits.

Regarding SDL3Main: The main benefit of the current approach is that we keep the game's native Win32 WinMain entry point and startup sequence intact.

To get rid of the #ifdef blocks in WinMain while minimizing duplication, I can move the window initialization out into SDL3Window.

Regarding splitting out subclasses: I don't think splitting the input handling into isolated SDL3Keyboard and SDL3Mouse subclasses is the right way. It runs contrary to how SDL3 tries to be a unified way; it relies on a single event pump where all keyboard, mouse, and gamepad signals flow together.

xezon · 2026-06-24T18:49:27Z

I don't think splitting the input handling into isolated SDL3Keyboard and SDL3Mouse subclasses is the right way.

But this is how you currently have set this up. What is the plan here?

- Updated vcpkg.json overrides and regenerated vcpkg-lock.json (sdl3 to 3.4.10, sdl3-image to 3.4.4). - Normalized formatting on vcpkg.json using the official vcpkg format-manifest tool. - Changed translateScanCodeToKeyVal parameter type to SDL_Scancode to prevent high-range media keys from wrapping into valid letter keycodes. - Documented SDL3_image FetchContent Git pin reasoning in cmake/sdl3.cmake. Co-authored-by: fbraz3 <fbraz3@users.noreply.github.com> Co-authored-by: Fighter19 <Fighter19@users.noreply.github.com> Co-authored-by: feliwir <feliwir@users.noreply.github.com>

Replace legacy block comment banners with line comments. Group and sort header includes. Break long gamepad input lines in SDL3Input.cpp with newlines. Remove Sage mentions.

…compatibility

bobtista · 2026-07-23T07:55:06Z

There's a lot of SDL stuff in my stack that you could use here, and I'd extract this into a separate SDL3Gamepad translator vs adopt its central input manager. See if Gippity can take a stab at taking the best of both

- Fix symbol collisions for g_strFile, g_csfFile, gAppPrefix, and TheWin32Mouse in WinMain - Call AppMain::initBeforeWindow() in WinMain prior to accessing splash screen and TheGlobalData - Use timeGetTime() for key down timestamping in SDL3Input to match Keyboard::checkKeyRepeat() - Release active synthetic inputs and reset state on gamepad close in SDL3InputManager - Read live CapsLock toggle state from SDL via SDL_GetModState() in getCapsState() Co-authored-by: Bobby Battista <bobtista@gmail.com>

- Add radial deadzone removal, smoothstep response curve, and velocity acceleration for analog sticks - Retire precision mode in favor of continuous stick acceleration (LT is currently unmapped) - Add getControllerScrollScale() to scale camera panning when zoomed close to ground - Suppress mouse edge scrolling automatically while gamepad input is active - Expose getMinHeightAboveGround and getMaxHeightAboveGround on View Co-authored-by: stm <14291421+stephanmeesters@users.noreply.github.com>

- Replace SDL_GetWindowSizeInPixels with SDL_GetWindowSize in scaleMouseCoordinates - Fixes HiDPI/Retina coordinate space mismatch where mouse & gamepad motion events delivered in logical points were scaled by physical pixel dimensions Co-authored-by: Bobby Battista <bobtista@gmail.com>

- Fix camera panning and scroll state handling for gamepads - Fix double-click detection for gamepad button pulses to trigger Guard mode orders

bobtista · 2026-07-24T13:03:24Z

+	, m_Window(window)
+	, m_IsCaptured(false)
+	, m_IsVisible(true)
+	, m_LostFocus(false)


m_LostFocus is initialized false but nothing ever sets it

bobtista · 2026-07-24T13:34:54Z

+		if (m_state.stickUp) virtualPulseKey(SDL_SCANCODE_UP, false);
+		if (m_state.stickDown) virtualPulseKey(SDL_SCANCODE_DOWN, false);
+
+		if (m_state.buttonState[SDL_GAMEPAD_BUTTON_SOUTH]) virtualPulseKey(SDL_SCANCODE_RETURN, false);


These releases no longer match the mappings below. South/east synthesize mouse buttons, west maps to A, right shoulder maps to Shift, and the D-pad ordering differs. Start and Back are also left out. Disconnecting while held can therefore leave inputs latched and release unrelated keys.
Should press/release share the same mapping table, maybe in a separate gamepad translator?

bobtista · 2026-07-24T13:35:34Z

+	float resolutionScale = 1.0f;
+	int windowWidth = 0;
+	int windowHeight = 0;
+	if (m_window && SDL_GetWindowSizeInPixels(m_window, &windowWidth, &windowHeight) && windowHeight > 0)


Gamepad cursor deltas are applied to SDL logical-point coordinates, but this scale uses physical pixel height. On HiDPI displays that changes cursor speed by the backing-scale factor. Should this use SDL_GetWindowSize(), matching scaleMouseCoordinates()?

bobtista · 2026-07-24T13:36:21Z

+	{
+		switch (event.type)
+		{
+			case SDL_EVENT_QUIT:


This exits immediately, whereas the Win32 close path sends MSG_META_DEMO_INSTANT_QUIT so an in-game close opens the quit flow and allows a sequenced multiplayer disconnect. Should SDL use that same path, falling back to setQuitting() only before the message stream is ready?

bobtista · 2026-07-24T13:37:12Z

+					closeGamepad();
+				break;
+
+			case SDL_EVENT_WINDOW_FOCUS_GAINED:


These events only update the mouse. The engine remains active, and keyboard state can stay held if key-up events are lost during Alt-Tab. Could focus handling update GameEngine::setIsActive() and reset keyboard state through an engine-level window-event handler

bobtista · 2026-07-24T13:37:46Z

+			case SDL_EVENT_KEY_DOWN:
+			case SDL_EVENT_KEY_UP:
+				if (!event.key.repeat)
+					addKeyboardSDLEvent(event);


SDL does not emit SDL_EVENT_TEXT_INPUT for Return. The text-entry gadgets commit on GWM_IME_CHAR(VK_RETURN), so chat and other entry fields may not submit. Could non-repeat Return/KP Enter key-down events send that message to the focused entry field?

bobtista · 2026-07-24T13:38:49Z

+	if (!m_gamepad)
+		return;
+
+	if (TheLookAtTranslator)


This marks controller input active whenever a gamepad is merely connected. canScrollAtScreenEdge() then disables physical-mouse edge scrolling for the entire session. Maybe track actual controller camera input or the last active input device instead?

bobtista · 2026-07-24T13:39:59Z

+
+void SDL3Mouse::init()
+{
+	Mouse::init();


The common client initialization later forces the engine mouse position to (0,0), but SDL may emit no motion event when the cursor is stationary. That can immediately trigger top-left edge scrolling, which I've run into, though I don't remember if it was from this. Can the mouse interface provide syncPositionToSystemCursor(), with SDL reading the live OS cursor instead of forcing the origin?

bobtista · 2026-07-24T13:40:55Z

+			return exitcode;
+		}
+
+		Uint32 flags = SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE;


The window is marked resizable, but the event pump does not handle SDL_EVENT_WINDOW_RESIZED, leaving the display resolution, UI layout, camera, and mouse bounds stale after a drag resize. I would remove SDL_WINDOW_RESIZABLE for this PR, or add deferred resize synchronization after the window size settles

bobtista · 2026-07-24T13:42:41Z

+
+	GameWindow* focusedWindow = TheWindowManager->winGetFocus();
+	const Bool wantsTextInput =
+		focusedWindow != nullptr && BitIsSet(focusedWindow->winGetStyle(), GWS_ENTRY_FIELD);


Editable combo boxes also take text input, but this only starts text input for GWS_ENTRY_FIELD, so typing into a focused combo box does nothing. Could it check GWS_COMBO_BOX too?

bobtista · 2026-07-24T13:44:39Z

It's improved a lot. I left more comments - also, there are thousands of lines changed in MainMenuUtils.cpp, CHATAPI.cpp, and both OptionsMenu.cpp that are just line ending stuff, could remove that and let a formatting pass deal with it later. My stack has working implementations of several of the inline items (close → MSG_META_DEMO_INSTANT_QUIT routing, focus → setIsActive + keyboard reset, Return → GWM_IME_CHAR commit, cursor position sync, deferred resize) if you want to lift from them.

githubawn force-pushed the feature/sdl3-input-backport branch from a785545 to 7cc0861 Compare April 20, 2026 15:00

greptile-apps Bot reviewed Apr 20, 2026

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greptile-apps Bot reviewed Apr 20, 2026

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greptile-apps Bot reviewed Apr 20, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp

OmniBlade reviewed Apr 20, 2026

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Comment thread cmake/sdl3.cmake Outdated

stephanmeesters reviewed Apr 20, 2026

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githubawn force-pushed the feature/sdl3-input-backport branch from e365605 to 627ef23 Compare April 20, 2026 18:24

githubawn changed the title ~~feat(input): Implement SDL3 input backend~~ feat(input): Implement SDL3 input and window management Apr 20, 2026

githubawn force-pushed the feature/sdl3-input-backport branch from eb9908a to 534e694 Compare April 21, 2026 01:17

greptile-apps Bot reviewed Apr 21, 2026

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Comment thread GeneralsMD/Code/Main/WinMain.cpp Outdated

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greptile-apps Bot reviewed Apr 21, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3GameEngine.cpp Outdated

githubawn commented Apr 21, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Cursor.cpp

DevGeniusCode added this to the Linux support milestone Apr 29, 2026

xezon added Gen Relates to Generals ZH Relates to Zero Hour Platform Work towards platform support, such as Linux, MacOS Input labels May 12, 2026

xezon reviewed May 12, 2026

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greptile-apps Bot reviewed Jun 1, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp

greptile-apps Bot reviewed Jun 9, 2026

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Comment thread vcpkg-lock.json

xezon reviewed Jun 14, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp Outdated

githubawn and others added 5 commits July 23, 2026 09:24

move cmake to RTS_BUILD_OPTION_SDL3, fix sorting

808f8d0

Move SDL3GameEngine files to Common directory.

81bf8f9

Replace legacy block comment banners with line comments. Group and sort header includes. Break long gamepad input lines in SDL3Input.cpp with newlines. Remove Sage mentions.

style/fix: address PR review feedback on SDL3 input and engine device

785d213

Refactor entry points: extract AppMain lifecycle and isolate SDL3Main

78f7e15

githubawn force-pushed the feature/sdl3-input-backport branch from 5da34d4 to 78f7e15 Compare July 23, 2026 07:26

bobtista reviewed Jul 23, 2026

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Comment thread Generals/Code/Main/CMakeLists.txt

fix(build): correct include ordering in AppMain and SDL3Main for VC6 …

6640a47

…compatibility

bobtista reviewed Jul 23, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp Outdated

bobtista reviewed Jul 23, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp

bobtista reviewed Jul 23, 2026

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greptile-apps Bot reviewed Jul 23, 2026

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Comment thread Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp Outdated

githubawn force-pushed the feature/sdl3-input-backport branch from ca6aa95 to 38bc8f6 Compare July 23, 2026 17:53

githubawn and others added 3 commits July 23, 2026 20:30

feat(sdl3): gamepad camera scrolling and double-click Guard mode

3bd8573

- Fix camera panning and scroll state handling for gamepads - Fix double-click detection for gamepad button pulses to trigger Guard mode orders

bobtista reviewed Jul 24, 2026

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githubawn force-pushed the feature/sdl3-input-backport branch from 0acb86c to 3bd8573 Compare July 25, 2026 16:05


		namespace {

		Bool DecodeNextUtf8Codepoint(const char* text, size_t length, size_t& offset, UnsignedInt& outCodepoint)

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Sequence Diagram

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