implemented right-click movement, up to speed with original c++ code

src/main.rs

@@ -4,13 +4,19 @@ fn main() {
     App::new()
         .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
-        .add_systems(Update, rotate_cube)
+        .add_systems(Update, (handle_click, move_to_target))
         .run();
 }
 
 #[derive(Component)]
-struct RotatingCube {
-    rotation_speed: f32,
+struct Player {
+    move_speed: f32,
+    height_offset: f32,
+}
+
+#[derive(Component)]
+struct MoveTarget {
+    position: Vec3,
 }
 
 fn setup(
@@ -29,8 +35,12 @@ fn setup(
         Mesh3d(meshes.add(Cuboid::new(2.0, 2.0, 2.0))),
         MeshMaterial3d(materials.add(Color::srgb(1.0, 0.0, 0.0))),
         Transform::from_xyz(0.0, 1.0, 0.0),
-        RotatingCube {
-            rotation_speed: 2.0,
+        Player {
+            move_speed: 10.0,
+            height_offset: 1.0,
+        },
+        MoveTarget {
+            position: Vec3::new(0.0, 0.0, 0.0),
         },
     ));
 
@@ -41,7 +51,7 @@ fn setup(
             shadows_enabled: true,
             ..default()
         },
-        Transform::from_xyz(10.0, 10.0, 10.0).looking_at(Vec3::ZERO, Vec3::Y),
+        Transform::from_xyz(0.0, 10.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
     ));
 
     // Plane
@@ -51,27 +61,67 @@ fn setup(
     ));
 }
 
-fn rotate_cube(
-    mut query: Query<
-        (
-            &mut Transform,
-            &RotatingCube,
-            &MeshMaterial3d<StandardMaterial>,
-        ),
-        Without<Camera3d>,
-    >,
-    time: Res<Time>,
-    mut materials: ResMut<Assets<StandardMaterial>>,
+fn handle_click(
+    mouse_button: Res<ButtonInput<MouseButton>>,
+    windows: Query<&Window>,
+    camera_query: Query<(&Camera, &GlobalTransform)>,
+    mut target_query: Query<&mut MoveTarget>,
 ) {
-    for (mut transform, rotating, material_handle) in query.iter_mut() {
-        transform.rotate_y(rotating.rotation_speed * time.delta_secs());
+    // Guard clause
+    if !mouse_button.just_pressed(MouseButton::Right) {
+        return;
+    }
 
-        // Get mutable reference to the actual material
-        if let Some(material) = materials.get_mut(&material_handle.0) {
-            let blue = (time.elapsed_secs().sin() + 1.0) / 2.0;
-            let red = 1.0 - blue;
-            let color = Color::srgb(red, 0.0, blue); // cycling colours
-            material.base_color = color;
+    let Ok(window) = windows.single() else {
+        return;
+    };
+
+    let Some(cursor_position) = window.cursor_position() else {
+        return;
+    };
+
+    let Ok((camera, camera_transform)) = camera_query.single() else {
+        return;
+    };
+
+    let Ok(ray) = camera.viewport_to_world(camera_transform, cursor_position) else {
+        return;
+    };
+
+    // check for sky clicks
+    if ray.direction.y > 0.0 {
+        return;
+    }
+
+    // Calculate the distance that the intercept with the ground occurs
+    let t = -ray.origin.y / ray.direction.y;
+
+    // plug T into our formula
+    let intersection = ray.origin + ray.direction * t;
+
+    for mut target in target_query.iter_mut() {
+        target.position = intersection;
+    }
+}
+
+fn move_to_target(mut query: Query<(&mut Transform, &MoveTarget, &Player)>, time: Res<Time>) {
+    for (mut transform, target, player) in query.iter_mut() {
+        let adjusted_target = target.position + Vec3::Y * player.height_offset;
+        let direction = adjusted_target - transform.translation;
+        let distance = direction.length();
+
+        // stop divide by 0 errors
+        if distance < 0.001 {
+            continue;
+        }
+
+        let move_amount = player.move_speed * time.delta_secs();
+
+        // Snap
+        if distance < move_amount {
+            transform.translation = adjusted_target;
+        } else {
+            transform.translation += direction.normalize() * move_amount;
         }
     }
 }