Added keyboard key to mouse control for scene viewer example (#4411)

# Objective

- Added keyboard control for scene_viewer example. Fixes #4407 


Co-authored-by: Troels Jessen <[email protected]>

Author: Troels Jessen

examples/tools/scene_viewer.rs

@@ -18,21 +18,21 @@ fn main() {
     println!(
         "
 Controls:
-    MOUSE  - Move camera orientation
-    LClick - Enable mouse movement
-    WSAD   - forward/back/strafe left/right
-    LShift - 'run'
-    E      - up
-    Q      - down
-    L      - animate light direction
-    U      - toggle shadows
-    C      - cycle through cameras
-    5/6    - decrease/increase shadow projection width
-    7/8    - decrease/increase shadow projection height
-    9/0    - decrease/increase shadow projection near/far
-
-    Space  - Play/Pause animation
-    Enter  - Cycle through animations
+    MOUSE       - Move camera orientation
+    LClick/M    - Enable mouse movement
+    WSAD        - forward/back/strafe left/right
+    LShift      - 'run'
+    E           - up
+    Q           - down
+    L           - animate light direction
+    U           - toggle shadows
+    C           - cycle through cameras
+    5/6         - decrease/increase shadow projection width
+    7/8         - decrease/increase shadow projection height
+    9/0         - decrease/increase shadow projection near/far
+
+    Space       - Play/Pause animation
+    Enter       - Cycle through animations
 "
     );
     App::new()
@@ -404,7 +404,8 @@ struct CameraController {
     pub key_up: KeyCode,
     pub key_down: KeyCode,
     pub key_run: KeyCode,
-    pub key_enable_mouse: MouseButton,
+    pub mouse_key_enable_mouse: MouseButton,
+    pub keyboard_key_enable_mouse: KeyCode,
     pub walk_speed: f32,
     pub run_speed: f32,
     pub friction: f32,
@@ -426,7 +427,8 @@ impl Default for CameraController {
             key_up: KeyCode::E,
             key_down: KeyCode::Q,
             key_run: KeyCode::LShift,
-            key_enable_mouse: MouseButton::Left,
+            mouse_key_enable_mouse: MouseButton::Left,
+            keyboard_key_enable_mouse: KeyCode::M,
             walk_speed: 5.0,
             run_speed: 15.0,
             friction: 0.5,
@@ -442,6 +444,7 @@ fn camera_controller(
     mut mouse_events: EventReader<MouseMotion>,
     mouse_button_input: Res<Input<MouseButton>>,
     key_input: Res<Input<KeyCode>>,
+    mut move_toggled: Local<bool>,
     mut query: Query<(&mut Transform, &mut CameraController), With<Camera>>,
 ) {
     let dt = time.delta_seconds();
@@ -477,6 +480,9 @@ fn camera_controller(
         if key_input.pressed(options.key_down) {
             axis_input.y -= 1.0;
         }
+        if key_input.just_pressed(options.keyboard_key_enable_mouse) {
+            *move_toggled = !*move_toggled;
+        }
 
         // Apply movement update
         if axis_input != Vec3::ZERO {
@@ -501,7 +507,7 @@ fn camera_controller(
 
         // Handle mouse input
         let mut mouse_delta = Vec2::ZERO;
-        if mouse_button_input.pressed(options.key_enable_mouse) {
+        if mouse_button_input.pressed(options.mouse_key_enable_mouse) || *move_toggled {
             for mouse_event in mouse_events.iter() {
                 mouse_delta += mouse_event.delta;
             }