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)	Precision Mode
RT (hold)	Force Attack (LCTRL)
LB	Select All (Q)
RB	Queue Orders (LSHIFT)
A	Left click
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: replicate to generals

greptile-apps · 2026-04-20T15:05:09Z

Greptile Summary

Implements an SDL3-based input and window backend (SDL3GameEngine, SDL3Mouse, SDL3Keyboard, SDL3InputManager, SDL3CursorManager) as a compile-time opt-in (RTS_SDL3_ENABLE) alternative to the existing Win32/DirectInput path. The feature is gated entirely in #if RTS_SDL3_ENABLE blocks with no impact on existing builds.

SDL3InputManager centralises all event dispatching into two fixed-size ring buffers (256 slots each) using SDL_EVENT_FIRST (= 0) as a sentinel; mouse coordinate scaling handles letterbox/viewport modes via the new Display::getViewportRect hook.
Gamepad support translates left-stick movement into synthetic SDL_EVENT_MOUSE_MOTION events (with correct windowID set), maps face/shoulder buttons to virtual keypresses, and routes D-pad to control-group hotkeys.
vcpkg-lock.json has been regenerated to match the sdl3@3.4.10 and sdl3-image@3.4.4 overrides in vcpkg.json, and the old builtin-baseline was correctly migrated to vcpkg-configuration.json.

Confidence Score: 5/5

The SDL3 backend is fully gated behind RTS_SDL3_ENABLE; existing Win32/DirectInput builds are unaffected. All previously identified compile and runtime correctness issues have been addressed in this revision.

The new SDL3 backend is additive and flag-gated, meaning the existing build path carries zero risk. The ring-buffer event queue, coordinate scaling, and gamepad mapping are all logically correct. The vcpkg lock now matches the declared overrides. Remaining findings are style-only.

GeneralsMD/Code/Main/WinMain.cpp (NULL literals) and Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp (inline-if inside lambdas) have minor style issues worth cleaning up before merge.

Important Files Changed

Filename	Overview
Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Input.cpp	New file: implements SDL3Mouse, SDL3Keyboard, and SDL3InputManager with ring-buffer event queuing and gamepad-to-keyboard/mouse mapping; inline if bodies inside lambdas violate the team's debuggability rule
Core/GameEngineDevice/Source/SDL3Device/Common/SDL3GameEngine.cpp	New file: SDL3GameEngine lifecycle (init/reset/update/poll), text input forwarding with correct UTF-8 decode, headless guard properly deferred past GameEngine::init()
Core/GameEngineDevice/Source/SDL3Device/GameClient/SDL3Cursor.cpp	New file: ANI/animated cursor loading via SDL3_image; delegates animation lifetime to SDL3 (SDL_CreateAnimatedCursor), correct cleanup in AnimatedCursor destructor
GeneralsMD/Code/Main/WinMain.cpp	SDL3 path added: window creation, splash screen blit, SDL3GameEngine factory; two new lines pass NULL instead of nullptr to SDL3 C++ APIs
GeneralsMD/Code/GameEngineDevice/Include/W3DDevice/GameClient/W3DGameClient.h	Conditional compile split: SDL3 path creates SDL3Mouse/SDL3Keyboard; Win32 path retains W3DMouse/DirectInputKeyboard; W3DSnow.h correctly moved outside the guard
Core/GameEngine/Include/GameClient/Display.h	Adds getViewportRect() virtual stub to Display base class, guarded by RTS_SDL3_ENABLE, returns FALSE for the no-letterbox default path
cmake/sdl3.cmake	New cmake module: vcpkg find_package with FetchContent fallback; SDL3 alias targets and static link helper added; SDL3_image lacks OVERRIDE_FIND_PACKAGE so mixed found/not-found states could redundantly trigger FetchContent for both libs
vcpkg.json	Adds sdl3 and sdl3-image dependencies with overrides pinned to 3.4.10 and 3.4.4; builtin-baseline correctly migrated to vcpkg-configuration.json default-registry
vcpkg-lock.json	Lock file regenerated: sdl3@3.4.10 and sdl3-image@3.4.4 now match vcpkg.json overrides; vcpkg-cmake-config entry added as expected new transitive dep
vcpkg-configuration.json	New file: default-registry carries the previous builtin-baseline, secondary registry pins SDL3/SDL3_image to a baseline with 3.4.x packages

Sequence Diagram

sequenceDiagram
    participant WM as WinMain
    participant SGE as SDL3GameEngine
    participant SIM as SDL3InputManager
    participant SMouse as SDL3Mouse
    participant SKbd as SDL3Keyboard
    participant GP as Gamepad

    WM->>SGE: CreateGameEngine() → new SDL3GameEngine
    WM->>WM: SDL_Init + SDL_CreateWindow
    SGE->>SIM: new SDL3InputManager(m_SDLWindow)
    SIM->>SIM: openFirstGamepad()

    loop Game loop
        SGE->>SGE: update()
        SGE->>SIM: update()
        SIM->>SIM: SDL_PollEvent()
        SIM->>SIM: addMouseSDLEvent / addKeyboardSDLEvent
        SIM->>SIM: processGamepadInput()
        GP-->>SIM: axis/button state
        SIM->>SIM: virtualPulseKey / virtualPulseMouse
        note over SIM: synthetic events injected into ring buffers
        SMouse->>SIM: getNextMouseEvent()
        SKbd->>SIM: getNextKeyboardEvent()
        SMouse->>SMouse: translateEvent → scaleMouseCoordinates
        SKbd->>SKbd: translateScanCodeToKeyVal
    end

_{Reviews (30): Last reviewed commit: "Move SDL3GameEngine files to Common dire..." | 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.

Consolidated all work from the test/sdl3-backport branch into a single atomic commit: - Centralized input management via SDL3InputManager. - Hardened Ani/RIFF cursor loading with robust bounds checking. - Native Gamepad support with analogue stick-to-mouse emulation and custom RTS mappings. - Modernized focus and capture handling for better stability during Alt-Tab. - Standardized and secured string operations throughout the SDL3 path.

Consolidated all work from the test/sdl3-backport branch into a single atomic commit: - Centralized input management via SDL3InputManager. - Hardened Ani/RIFF cursor loading with robust bounds checking. - Native Gamepad support with analogue stick-to-mouse emulation and custom RTS mappings. - Modernized focus and capture handling for better stability during Alt-Tab. - Standardized and secured string operations throughout the SDL3 path. - Updated credit attribution (fbraz3).

xezon

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

xezon · 2026-05-05T19:42:03Z

+
+#if SAGE_USE_SDL3
+    #include <SDL3/SDL.h>
+    #include "SDL3GameEngine.h"


This SDL code is added to a file called WinMain (for Windows). Is this intentional?

This was intentional. The SDL3 input backend is designed with a future splitscreen skirmish feature in mind, supporting multiple simultaneous mice/keyboards so that 2–8 players can share a single machine rather than needing separate computers, either controlling the same or unique armies.

SDL3 input doesn't function without an SDL window, so creating the window here was the minimum viable approach to make the input backend functional. The Win32/DirectInput path doesn't lend itself to the multi-device model SDL3 enables, which is why SDL3 is the foundation for this direction.

Shouldn't we have a SDL3Main then? I have seen other forks do that.

Maybe make WinMain and SDL3Main share code if they do. But basically get rid of the ifdef approach.

xezon · 2026-05-05T19:46:07Z

+
+ParticleSystemManager* SDL3GameEngine::createParticleSystemManager(Bool dummy)
+{
+	(void)dummy;


Why not create dummy here?

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.

xezon · 2026-05-12T18:07:44Z

+	  m_gamepad(nullptr),
+	  m_precisionMode(FALSE),
+	  m_lastUpdateTime(0),
+	  m_isQuitting(FALSE)


Or use false

xezon · 2026-05-12T18:09:09Z

+	handleGamepadButton(SDL_GAMEPAD_BUTTON_DPAD_RIGHT, m_state.buttonState[SDL_GAMEPAD_BUTTON_DPAD_RIGHT], SDL_GetGamepadButton(m_gamepad, SDL_GAMEPAD_BUTTON_DPAD_RIGHT), [&](bool d){ virtualPulseKey(SDL_SCANCODE_3, d); });
+	handleGamepadButton(SDL_GAMEPAD_BUTTON_DPAD_DOWN, m_state.buttonState[SDL_GAMEPAD_BUTTON_DPAD_DOWN], SDL_GetGamepadButton(m_gamepad, SDL_GAMEPAD_BUTTON_DPAD_DOWN), [&](bool d){ virtualPulseKey(SDL_SCANCODE_4, d); });
+	handleGamepadButton(SDL_GAMEPAD_BUTTON_LEFT_STICK, m_state.buttonState[SDL_GAMEPAD_BUTTON_LEFT_STICK], SDL_GetGamepadButton(m_gamepad, SDL_GAMEPAD_BUTTON_LEFT_STICK), [&](bool d){ if (d) TheMessageStream->appendMessage(GameMessage::MSG_META_SELECT_NEXT_IDLE_WORKER); });
+	handleGamepadButton(SDL_GAMEPAD_BUTTON_RIGHT_STICK, m_state.buttonState[SDL_GAMEPAD_BUTTON_RIGHT_STICK], SDL_GetGamepadButton(m_gamepad, SDL_GAMEPAD_BUTTON_RIGHT_STICK), [&](bool d){ if (d) TheMessageStream->appendMessage(GameMessage::MSG_META_VIEW_COMMAND_CENTER); });


These lines are awfully long.

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.

…ckport

…backport

removed most ANI cursor hacks

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?

- Switched SDL3_image to the latest GitHub main branch commit to natively resolve the RIFF/ANI odd-chunk parsing bug. - Removed the legacy cbSize header patching workaround in SDL3CursorManager::loadANI. - Kept base SDL3 library pinned to stable release-3.4.10. - Cleaned up transient code-level header comments. 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>

- Replaced (void) with empty parentheses () in SDL3Input and SDL3GameEngine declarations and definitions. 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>

- 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.

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

greptile-apps Bot reviewed Apr 20, 2026

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

greptile-apps Bot reviewed Apr 20, 2026

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

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 added 10 commits April 21, 2026 03:16

added build guards

e3b674b

greptile feedback

2499e0b

greptile feedback

f8fb43f

fixed build error

4ac91e0

greptile feedback

a0ac8f4

added vcpkg

d9d9ff0

vcpkg fix

d048867

changed dpad group numbers

534e694

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

switch back to static linking

09fd4e6

greptile-apps Bot reviewed Apr 21, 2026

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

githubawn added 3 commits April 21, 2026 17:40

move SDL3_image out SDL3input

9b0262c

properly fail on SDL_INIT failure

3a40b11

removed custom ICO decoder

4d82b81

greptile-apps Bot reviewed Apr 21, 2026

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

githubawn added 2 commits April 21, 2026 18:48

fixes SDL_WarpMouseInWindow mismatch

884218b

removed some dead declarations

b268cda

greptile-apps Bot reviewed Apr 21, 2026

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

temporary re-added custom decoder

a7883e8

githubawn commented Apr 21, 2026

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

dont early return for headless mode

038aea0

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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githubawn added 4 commits May 14, 2026 18:10

applied clang to files new in this PR

390e2ee

Merge remote-tracking branch 'origin/main' into feature/sdl3-input-ba…

0ead8ea

…ckport

Merge remote-tracking branch 'upstream/main' into feature/sdl3-input-…

6f04138

…backport

updated SDL to latest version

ed87bcb

removed most ANI cursor hacks

greptile-apps Bot reviewed Jun 1, 2026

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

githubawn added 2 commits June 1, 2026 20:10

renamed SAGE_USE_SDL3 to RTS_SDL3_ENABLE

c0f22b9

cleaned up comments

e578a8b

greptile-apps Bot reviewed Jun 9, 2026

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Comment thread vcpkg-lock.json

githubawn and others added 4 commits June 10, 2026 00:37

move cmake to RTS_BUILD_OPTION_SDL3, fix sorting

4541255

Move SDL3GameEngine files to Common directory.

0921b16

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.


		namespace {

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

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Greptile Summary

Confidence Score: 5/5

Important Files Changed

Sequence Diagram

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