godosa-engine: initial public history

1 files changed, 107 insertions, 0 deletions

diff --git a/src/Godosa.Gamepad/SdlGamepadSource.cs b/src/Godosa.Gamepad/SdlGamepadSource.cs
new file mode 100644
index 0000000..ee63161
--- /dev/null
+++ b/src/Godosa.Gamepad/SdlGamepadSource.cs
@@ -0,0 +1,107 @@
+using System;
+using System.Numerics;
+using Godosa.Core.Diagnostics;
+using Godosa.Core.Input;
+using Silk.NET.SDL;
+
+namespace Godosa.Gamepad;
+
+/// <summary>
+/// Reads the first attached game controller through windowless SDL. Returns raw
+/// held state; each game maps it (and applies deadzones). Any SDL failure disables
+/// the pad for the session and the game stays keyboard-only.
+/// </summary>
+public sealed unsafe class SdlGamepadSource : IDisposable
+{
+    private Sdl? _sdl;
+    private GameController* _pad;
+    private bool _failed;
+
+    public GamepadState? Poll()
+    {
+        if (_failed) return null;
+        try
+        {
+            if (_sdl is null && !Init()) return null;
+            var sdl = _sdl!;
+            sdl.GameControllerUpdate(); // also detects hot-plug (~1.4 µs/call)
+
+            if (_pad != null && sdl.GameControllerGetAttached(_pad) != SdlBool.True)
+            {
+                sdl.GameControllerClose(_pad);
+                _pad = null;
+                if (EngineDebug.Input) EngineDebug.Write("input", "gamepad detached");
+            }
+            if (_pad == null && !Open(sdl)) return null;
+
+            var buttons = PadButtons.None;
+            foreach (var (sdlButton, pad) in ButtonMap)
+                if (sdl.GameControllerGetButton(_pad, sdlButton) != 0) buttons |= pad;
+            return new GamepadState(
+                new Vector2(Axis(sdl, GameControllerAxis.Leftx), Axis(sdl, GameControllerAxis.Lefty)),
+                new Vector2(Axis(sdl, GameControllerAxis.Rightx), Axis(sdl, GameControllerAxis.Righty)),
+                Math.Max(0f, Axis(sdl, GameControllerAxis.Triggerleft)),
+                Math.Max(0f, Axis(sdl, GameControllerAxis.Triggerright)),
+                buttons);
+        }
+        catch (Exception ex)
+        {
+            if (EngineDebug.Input) EngineDebug.Write("input", $"gamepad disabled: {ex.Message}");
+            _failed = true;
+            return null;
+        }
+    }
+
+    private static readonly (GameControllerButton Sdl, PadButtons Pad)[] ButtonMap =
+    {
+        (GameControllerButton.A, PadButtons.A), (GameControllerButton.B, PadButtons.B),
+        (GameControllerButton.X, PadButtons.X), (GameControllerButton.Y, PadButtons.Y),
+        (GameControllerButton.Back, PadButtons.Back), (GameControllerButton.Start, PadButtons.Start),
+        (GameControllerButton.Leftshoulder, PadButtons.LeftShoulder), (GameControllerButton.Rightshoulder, PadButtons.RightShoulder),
+        (GameControllerButton.DpadUp, PadButtons.DpadUp), (GameControllerButton.DpadDown, PadButtons.DpadDown),
+        (GameControllerButton.DpadLeft, PadButtons.DpadLeft), (GameControllerButton.DpadRight, PadButtons.DpadRight),
+    };
+
+    private bool Init()
+    {
+        var sdl = Sdl.GetApi();
+        sdl.SetHint(Sdl.HintJoystickAllowBackgroundEvents, "1"); // the Avalonia window has focus, not SDL
+        sdl.SetHint(Sdl.HintNoSignalHandlers, "1");
+        if (sdl.InitSubSystem(Sdl.InitGamecontroller) != 0)
+        {
+            if (EngineDebug.Input) EngineDebug.Write("input", $"gamepad disabled: {sdl.GetErrorS()}");
+            _failed = true;
+            return false;
+        }
+        sdl.JoystickEventState(0); // SDL_IGNORE: state is polled; nothing drains SDL's event queue
+        sdl.GameControllerEventState(0);
+        _sdl = sdl;
+        return true;
+    }
+
+    private bool Open(Sdl sdl)
+    {
+        int count = sdl.NumJoysticks();
+        for (int i = 0; i < count; i++)
+        {
+            if (sdl.IsGameController(i) != SdlBool.True) continue;
+            _pad = sdl.GameControllerOpen(i);
+            if (_pad == null) continue;
+            if (EngineDebug.Input) EngineDebug.Write("input", $"gamepad attached: {sdl.GameControllerNameS(_pad)}");
+            return true;
+        }
+        return false;
+    }
+
+    private float Axis(Sdl sdl, GameControllerAxis axis) =>
+        Math.Clamp(sdl.GameControllerGetAxis(_pad, axis) / 32767f, -1f, 1f);
+
+    public void Dispose()
+    {
+        if (_sdl is null) return;
+        if (_pad != null) _sdl.GameControllerClose(_pad);
+        _pad = null;
+        _sdl.QuitSubSystem(Sdl.InitGamecontroller);
+        _sdl = null;
+    }
+}