Added keyboard scan input event (bevyengine#5495)

# Objective

- I wanted to have controls independent from keyboard layout and found that bevy doesn't have a proper implementation for that

## Solution

- I created a `ScanCode` enum with two hundreds scan codes and updated `keyboard_input_system` to include and update `ResMut<Input<ScanCode>>`
- closes both bevyengine#2052 and bevyengine#862

Co-authored-by: Bleb1k <91003089+Bleb1k@users.noreply.github.com>

crates/bevy_input/src/keyboard.rs

@@ -24,25 +24,29 @@ pub struct KeyboardInput {
 ///
 /// ## Differences
 ///
-/// The main difference between the [`KeyboardInput`] event and the [`Input<KeyCode>`] resource is that
-/// the latter has convenient functions like [`Input::pressed`], [`Input::just_pressed`] and [`Input::just_released`].
+/// The main difference between the [`KeyboardInput`] event and the [`Input<KeyCode>`] or [`Input<ScanCode>`] resources is that
+/// the latter have convenient functions such as [`Input::pressed`], [`Input::just_pressed`] and [`Input::just_released`].
 pub fn keyboard_input_system(
-    mut keyboard_input: ResMut<Input<KeyCode>>,
+    mut scan_input: ResMut<Input<ScanCode>>,
+    mut key_input: ResMut<Input<KeyCode>>,
     mut keyboard_input_events: EventReader<KeyboardInput>,
 ) {
-    keyboard_input.clear();
+    scan_input.clear();
+    key_input.clear();
     for event in keyboard_input_events.iter() {
-        if let KeyboardInput {
-            key_code: Some(key_code),
-            state,
-            ..
-        } = event
-        {
+        let KeyboardInput {
+            scan_code, state, ..
+        } = event;
+        if let Some(key_code) = event.key_code {
             match state {
-                ButtonState::Pressed => keyboard_input.press(*key_code),
-                ButtonState::Released => keyboard_input.release(*key_code),
+                ButtonState::Pressed => key_input.press(key_code),
+                ButtonState::Released => key_input.release(key_code),
             }
         }
+        match state {
+            ButtonState::Pressed => scan_input.press(ScanCode(*scan_code)),
+            ButtonState::Released => scan_input.release(ScanCode(*scan_code)),
+        }
     }
 }
 
@@ -51,7 +55,7 @@ pub fn keyboard_input_system(
 /// ## Usage
 ///
 /// It is used as the generic `T` value of an [`Input`](crate::Input) to create a `Res<Input<KeyCode>>`.
-/// The resource stores the data of the buttons of a keyboard and can be accessed inside of a system.
+/// The resource values are mapped to the current layout of the keyboard and correlate to an [`ScanCode`](ScanCode).
 ///
 /// ## Updating
 ///
@@ -407,3 +411,17 @@ pub enum KeyCode {
     /// The `Cut` key.
     Cut,
 }
+
+/// The scan code of a [`KeyboardInput`](crate::keyboard::KeyboardInput).
+///
+/// ## Usage
+///
+/// It is used as the generic <T> value of an [`Input`](crate::Input) to create a `Res<Input<ScanCode>>`.
+/// The resource values are mapped to the physical location of a key on the keyboard and correlate to an [`KeyCode`](KeyCode)
+///
+/// ## Updating
+///
+/// The resource is updated inside of the [`keyboard_input_system`](crate::keyboard::keyboard_input_system).
+#[derive(Debug, Hash, Ord, PartialOrd, PartialEq, Eq, Clone, Copy)]
+#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+pub struct ScanCode(pub u32);

crates/bevy_input/src/lib.rs

@@ -16,15 +16,15 @@ pub mod prelude {
             Gamepad, GamepadAxis, GamepadAxisType, GamepadButton, GamepadButtonType, GamepadEvent,
             GamepadEventType, Gamepads,
         },
-        keyboard::KeyCode,
+        keyboard::{KeyCode, ScanCode},
         mouse::MouseButton,
         touch::{TouchInput, Touches},
         Axis, Input,
     };
 }
 
 use bevy_app::prelude::*;
-use keyboard::{keyboard_input_system, KeyCode, KeyboardInput};
+use keyboard::{keyboard_input_system, KeyCode, KeyboardInput, ScanCode};
 use mouse::{mouse_button_input_system, MouseButton, MouseButtonInput, MouseMotion, MouseWheel};
 use prelude::Gamepads;
 use touch::{touch_screen_input_system, TouchInput, Touches};
@@ -47,6 +47,7 @@ impl Plugin for InputPlugin {
             // keyboard
             .add_event::<KeyboardInput>()
             .init_resource::<Input<KeyCode>>()
+            .init_resource::<Input<ScanCode>>()
             .add_system_to_stage(
                 CoreStage::PreUpdate,
                 keyboard_input_system.label(InputSystem),