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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;
}
}
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