feat: Add mouse wheel support for game input passthrough

- Implement mouse wheel event handling in SDL2 backend (emu_window_sdl2)
- Add wheel event routing from GRenderWindow to input subsystem
- Add debugging logs to trace mouse wheel events through input chain
- Support mouse wheel input for mods like Ultracam when games are running (WIP)

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/hid_core/frontend/emulated_devices.cpp

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <algorithm>
@@ -374,6 +375,7 @@ void EmulatedDevices::SetMouseWheel(const Common::Input::CallbackStatus& callbac
     const auto analog_value = TransformToAnalog(callback);
 
     device_status.mouse_wheel_values[index] = analog_value;
+    LOG_DEBUG(Input, "EmulatedDevices::SetMouseWheel: index={}, value={}", index, analog_value.value);
 
     if (is_configuring) {
         device_status.mouse_wheel_state = {};
@@ -455,6 +457,11 @@ AnalogStickState EmulatedDevices::GetMouseWheel() const {
     return device_status.mouse_wheel_state;
 }
 
+void EmulatedDevices::ResetMouseWheel() {
+    std::scoped_lock lock{mutex};
+    device_status.mouse_wheel_state = {};
+}
+
 void EmulatedDevices::TriggerOnChange(DeviceTriggerType type) {
     std::scoped_lock lock{callback_mutex};
     for (const auto& poller_pair : callback_list) {

src/hid_core/frontend/emulated_devices.h

@@ -135,6 +135,9 @@ public:
     /// Returns the latest mouse wheel change
     AnalogStickState GetMouseWheel() const;
 
+    /// Resets the mouse wheel state (should be called each frame)
+    void ResetMouseWheel();
+
     /**
      * Adds a callback to the list of events
      * @param update_callback InterfaceUpdateCallback that will be triggered

src/hid_core/resources/mouse/debug_mouse.cpp

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "core/core_timing.h"
@@ -55,6 +56,9 @@ void DebugMouse::OnUpdate(const Core::Timing::CoreTiming& core_timing) {
         next_state.delta_wheel_y = mouse_wheel_state.y - last_mouse_wheel_state.y;
 
         last_mouse_wheel_state = mouse_wheel_state;
+
+        // Reset mouse wheel state after reading to ensure delta values work correctly
+        emulated_devices->ResetMouseWheel();
         next_state.button = mouse_button_state;
     }
 

src/hid_core/resources/mouse/mouse.cpp

@@ -55,6 +55,9 @@ void Mouse::OnUpdate(const Core::Timing::CoreTiming& core_timing) {
         next_state.delta_wheel_y = mouse_wheel_state.y - last_mouse_wheel_state.y;
 
         last_mouse_wheel_state = mouse_wheel_state;
+
+        // Reset mouse wheel state after reading to ensure delta values work correctly
+        emulated_devices->ResetMouseWheel();
         next_state.button = mouse_button_state;
     }